EP4380943A1

EP4380943A1 - Method for the silylation of a c-h bond with a silylated diazene

Info

Publication number: EP4380943A1
Application number: EP21824011.7A
Authority: EP
Inventors: Clément CHAUVIER; Louis FENSTERBANK; Lucien FRANCK
Original assignee: Centre National de la Recherche Scientifique CNRS; Sorbonne Universite
Current assignee: Centre National de la Recherche Scientifique CNRS; Sorbonne Universite
Priority date: 2021-08-05
Filing date: 2021-08-05
Publication date: 2024-06-12
Also published as: WO2023012494A1

Abstract

The present invention relates to a method for forming a silylated compound comprising the step of reacting an organic substrate comprising at least one silylatable C-H bond with a mixture comprising: (a) a silylated diazene of formula (I) and (b) a catalyst. The present invention also relates to a composition comprising: (a') a silylated compound, (b') at least one impurity resulting from the reaction of an organic substrate comprising at least one silylatable C-H bond with a mixture comprising: - a silylated diazene of formula (I) as defined above, and - a catalyst.

Description

Method for the silylation of a C-H bond with a silylated diazene Field of the invention The present invention relates to a new method for the silylation of a C-H bond in an organic substrate using a silylated diazene derivative. Background of the present invention Organosilanes have become invaluable chemical tools in fields as diverse as drug discovery and polymer synthesis or as intermediates in synthetic chemistry. Most carbosilanes have traditionally been synthesized from the corresponding (pseudo)halides (bromide, iodide or triflate) through stoichiometric or catalytic procedures. The direct intermolecular silylation of C–H bonds represents an attractive atom-economical alternative as it bypasses the substrate pre-functionalization step, yet poses significant reactivity and selectivity challenges. In this respect, the most common strategy relies on stoichiometric C–H metalation reactions mediated by organolithium (RLi) or Grignard (RMgX) strong Brønsted bases followed by trapping the metalated species with chloro- or alkoxysilanes. However, large amount of metallic wastes are generated after silylation and the handling of the metalating agents usually requires special precautions only accessible to highly trained workers in the field. Most recent research effort has therefore been devoted to uncover catalytic systems that facilitate the C–H silylation of various substrate classes, while the silylating reagents employed remained almost exclusively an hydrosilane (R3Si–H).¹ With the latter silicon source, the catalytic dehydrogenative silylation of arenes bearing various directing groups² was first developed and later extended to unbiased substrates.³ However, these developments rely on expensive precious transition metals (mostly Ir or Rh-based) that operate at high temperature and elaborated ligands are often required to achieve synthetically useful reactivity and selectivity. Transition metal-free catalytic C(sp²)–H silylation reactions with hydrosilanes have also been described, though general contributions that compete with the aforementioned approaches remain scarce.⁴ For example, the use of potent Brønsted or Lewis acids catalysts⁵ is restricted to electron-rich (hetero)aromatic substrates, while the polarity of silyl radicals limits photocatalytic silylation strategies to electron-poor heterocycles.⁶ Brønsted bases have nonetheless recently emerged as relatively general C–H silylation catalysts. In 2015, Grubbs, Stoltz and coworkers demonstrated that the combination of hydrosilanes (e.g. Et₃SiH) with catalytic amount of potassium alkoxides (e.g. tBuOK) allows the dehydrogenative silylation of a range of heteroarenes, including indole derivatives.⁷ While operationally simple, cost-effective and scalable, this protocol is mostly restricted to aromatic heterocycles devoid of halides as well as electron withdrawing groups and barely expand to arenes.⁸ Finally, the transition metal-free catalytic silylation of unactivated C(sp³)–H bonds remains a barely solved challenge (for a review on TM-catalyzed C(sp³)–H silylation reactions, see: Chem. Soc. Rev., 2021,50, 5062-5085). Beyond kinetic factors (catalyst structure and reactivity), the lack of generality and/or the requirement of harsh reaction conditions in the typical catalytic C–H silylation reactions with hydrosilanes may also be ascribed to thermodynamic grounds.⁹ As an illustration, the dehydrogenative silylation of most (hetero)arenes with trialkylhydrosilanes (R3Si–H, R = alkyl) is endergonic under standard conditions and the equilibrium must usually be shifted to the product side, for example by continuous H₂ removal with excess olefin additives. Improved silylation energetics can be reached with vinylsilanes¹⁰ or disilanes¹¹ silicon sources, yet without genuine kinetic improvements compared to the reaction mediated by commercially available hydrosilanes. Kondo and co-workers showed that a more polarized silicon source, namely CF3SiMe3, enables the exergonic silylation of furan and thiophene derivatives¹² but also of electron poor difluoroaromatic compounds¹³ simply upon treatment with catalytic amount of fluoride salts. The silylation of less acidic substrates such as indoles has remained, however, undescribed presumably because of a lack of kinetic basicity of the generated CF₃ ^– anion.¹⁴ Critical reflection of the state-of-the-art shows that a transition metal-free catalytic system, able to induce the selective silylation of unactivated C–H bonds under mild conditions and in a general manner, still has to be developed. In particular, there is a need for a C–H silylation system that would combine the atom-economy provided by catalysis with the cost- effectiveness, generality and tunable deprotonation ability of aforementioned s-block-based potent metalation reagents. The inventors of the present invention have unexpectedly developed a new method for the silylation of a C-H bond in an organic substrate by using silylated diazene as silylation agents. The latter are readily accessible from commercially available precursors and their structure enable the exergonic C–H bond silylation of unactivated heteroaryl and aryl compounds as well as benzylic and allylic substrates under ambient transition-metal free catalytic conditions. Summary of the invention The present invention relates to a method for forming a silylated compound comprising the step of reacting an organic substrate comprising at least one silylatable C-H bond with a mixture comprising: (a) a silylated diazene of formula (I) wherein R is selected in the group consisting of C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, aryl, heteroaryl, heterocycloalkyl, C₃-C₇ cycloalkyl, Si(C₁-C₆alkyl)₃ and Si(O-C₁-C₆ alkyl)₃, said alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycloalkyl and cycloalkyl being optionally substituted, and R¹, R² and R³ are each independently selected in the group consisting of H, C1-C12 alkyl, C2- C12 alkenyl, C2-C12 alkynyl, C1-C12 alcoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocycloalkyl, C₃-C₇ cycloalkyl, halogen and siloxy, said alkyl, alkenyl, alkynyl, alcoxy, aryl, aryloxy heteroaryl, heteroaryloxy, siloxy, heterocycloalkyl and cycloalkyl being optionally substituted, and (b) a catalyst. The present invention also relates to a composition comprising: (a’) a silylated compound, (b’) at least one impurity resulting from the reaction of an organic substrate comprising at least one silylatable C-H bond with a mixture comprising: - a silylated diazene of formula (I) wherein R is selected in the group consisting of C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, aryl, heteroaryl, heterocycloalkyl, C₃-C₇ cycloalkyl, Si(C₁-C₆alkyl)₃ and Si(O-C₁-C₆ alkyl)₃, said alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycloalkyl and cycloalkyl being optionally substituted, and R¹, R² and R³ are each independently selected in the group consisting of H, C1-C12 alkyl, C2- C12 alkenyl, C2-C12 alkynyl, C1-C12 alcoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocycloalkyl, C3-C7 cycloalkyl, halogen and siloxy, said alkyl, alkenyl, alkynyl, alcoxy, aryl, aryloxy heteroaryl, heteroaryloxy, siloxy, heterocycloalkyl and cycloalkyl being optionally substituted, and - a catalyst. The present invention also relates to the use of a silylated diazene of formula (I) in a method for forming a silylated compound. Detailed description Definitions As described herein, the present invention relates to methods and compositions for transforming an organic substrate into the corresponding silylated compound. In other words, the methods and the compositions of the present invention enable to introduce a silyl group in an organic substrate. In particular, the present invention aims at silylating one or more C-H bond(s) in an organic substrate, meaning that the C-H bond(s) is (are) replaced by a C-Si bond(s). The term “stereoisomers” used in this invention refers to configurational stereoisomers and more particularly to optical isomers. Optical isomers that are not mirror images of one another are thus designated as “diastereoisomers”, and optical isomers, which are non- superimposable mirror images are designated as “enantiomers”. An equimolar mixture of two enantiomers of a chiral compound is designated as a racemic mixture or racemate. The term "organic substrate enriched with an isotope" means that the organic substrate of interest has a proportion of said isotope that is significantly greater than the natural isotopic abundance. A “silylatable C–H bond” as employed herein refers to the C–H bond(s) within an organic substrate that will be preferentially silylated (e.g. on electronic and/or steric grounds) in the claimed method. When several C–H bonds are present within the organic subtrate, the “silylatable C–H bond(s)” can generally be identified as the most acidic (i.e. with lower pKa) C–H bond(s), though exceptions may occur because the kinetics of the silylation does not only depend on the said-acidity, which is a thermodynamic parameter. The term “halogen”, as used in the present invention, refers to a fluorine, bromine, chlorine or iodine atom. The term “C_x-C_y aliphatic chain" designates a linear or branched hydrocarbon chain, completely saturated or containing one or more unsaturations, but not aromatic, comprising from x to y carbon atoms, notably from 1 to 12 carbon atoms, preferably from 1 to 6 carbon atoms. According to the present invention, the term "aliphatic chain" includes substituted or unsubstituted, linear or branched, alkyl, alkenyl or alkynyl groups. The term “C_x-C_y alkyl”, as used in the present invention, refers to a straight or branched monovalent saturated hydrocarbon chain containing from x to y carbon atoms, notably 1 to 12, including, but not limited to, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec- butyl, t-butyl, n-pentyl, n-hexyl, and the like. The term “alkene”, as used in the present invention, refers to a straight or branched mono- or polyunsaturated hydrocarbon compound comprising at least one double bond. Preferably, the alkene according to the present invention contains from 2 to 18 carbon atoms, more preferably from 2 to 12 carbon atoms. Examples of alkene include, but are not limited to, ethylene, propene, butene, pentene, hexene and the like. The term “Cx-Cy alkenyl”, as used in the present invention, refers to a straight or branched monovalent unsaturated hydrocarbon chain containing from x to y carbon atoms, notably from 2 to 12, and comprising at least one double bond including, but not limited to, ethenyl, propenyl, butenyl, pentenyl, hexenyl and the like. The term “alkyne” as used in the present invention, refers to a straight or branched unsaturated hydrocarbon compound comprising at least one triple bond. Preferably, the alkyne according to the present invention contains from 2 to 18 carbon atoms, more preferably from 2 to 12 carbon atoms. Examples of alkyne include, but are not limited to, acetylene, propyne, butyne, pentyne, hexyne and the like. The term “C_x-C_y alkynyl”, as used in the present invention, refers to a straight or branched monovalent unsaturated hydrocarbon chain containing from x to y carbon atoms, notably from 2 to 12, and comprising at least one triple bond including, but not limited to, ethynyl, propynyl, propynyl, butynyl, pentynyl, hexynyl and the like. The term "C_x-C_y haloalkyl" refers to a C_x-C_y alkyl chain as defined above wherein one or more hydrogen atoms are replaced by a halogen atom selected from fluorine, chlorine, bromine or iodine, preferably a fluorine atom. For example, it is a CF3 group. The term “carbocyclyl” refers to a saturated hydrocarbon ring, preferably comprising from 3 to 7 carbons, including cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl. The term “heterocycloalkyl” as used in the present invention refers to a non-aromatic, saturated or unsaturated monocycle or polycycle (comprising fused, bridged or spiro rings) comprising preferably 5 to 10, notably 5 or 6, atoms in the ring(s), in which the atoms of the ring(s) consist of carbon atoms and one or more, advantageously 1 to 4, and more advantageously 1 or 2, heteroatoms, such as a nitrogen, oxygen or sulphur atom, the remainder being carbon atoms. In particular, it can be an unsaturated ring, such as an unsaturated 5 or 6-membered monocycle. Preferably it comprises 1 or 2 nitrogen(s), in particular one. A heterocycle can be notably piperidinyl, piperizinyl, pyrrolidinyl, pyrazolidinyl, imidazolidinyl, azepanyl, thiazolidinyl, isothiazolidinyl, oxazocanyl, thiazepanyl, benzimidazolonyl. The term “arene”, as used in the present invention, refers to an aromatic hydrocarbon compound comprising one or more fused rings. Preferably, the arene according to the present invention comprises from 6 to 12 carbon atoms, more preferably from 6 to 10 carbon atoms. Examples of arene include, but are not limited to, benzene, naphthalene or anthracene. The term "aryl" refers to an aromatic hydrocarbon group preferably comprising from 6 to 12 carbon atoms and comprising one or more fused rings, such as, for example, a phenyl, a naphthyl or an anthracenyl group. Advantageously, it is a phenyl group. The term “heteroarene” as used in the present invention, refers to an aromatic compound comprising one or several, notably one or two, fused hydrocarbon cycles in which one or several, notably one to four, advantageously one or two, carbon atoms each have been replaced with heteroatoms selected from a sulfur atom, an oxygen atom and a nitrogen atom, preferably selected from an oxygen atom and a nitrogen atom. Preferably, the heteroarene according to the present invention comprises from 5 to 12 carbon atoms, preferably from 5 to 10 carbon atoms. Examples of heteroarene include, but are not limited to, pyridine, pyrazine, pyridazine, pyrimidine, triazine, furan, benzofuran, benzopyrrole, benzothiophene, isobenzofuran, isobenzopyrrole, isobenzothiophene, pyrrole, indole, isoindole, indolizine, imidazole, pyrazole, triazole, pyrazine, thiophene, oxazole, thiazole, isoxazole, isothiazole, oxadiazole, quinoline, isoquinoline and thiadiazole. The term “heteroaryl”, as used in the present invention, refers to an aromatic group comprising one or several, notably one or two, fused hydrocarbon cycles in which one or several, notably one to four, advantageously one or two, carbon atoms each have been replaced with heteroatoms selected from a sulfur atom, an oxygen atom and a nitrogen atom, preferably selected from an oxygen atom and a nitrogen atom. Preferably, the heteroaryl contains 5 to 12 carbon atoms, notably 5 to 10. It can be a furyl, thienyl, pyrrolyl, pyridyl, benzofuranyl, benzopyrrolyl, benzothipohenyl, isobenzofuranyl, isobenzopyrrolyl, isobenzothiophenyl, oxazolyl, isoxazolyl, thiazolyle, isothiazolyl, imidazolyl, pyrazolyl, oxadiazolyl, thiadiazolyl, triazolyl, tetrazolyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, quinolyl, isoquinolyl, quinoxalyl or indyl. The terms “C_x-C_y-alkoxy”, “aryloxy” or “heteroaryloxy” refer to those C_x-C_y alkyl, aryl or heteroaryl groups as defined above attached to the remainder of the molecule by an oxygen atom. Examples of alkoxy groups include, but are not limited to, methoxy and ethoxy. Examples of aryloxy groups include, but are not limited to, phenoxy and naphtoxy. The term “siloxy” refers to a univalent silyl group attached to the remainder of the molecule by an oxygen atom. A “silyl group” refers to a group constituted by a silicium atom to which 3 substituents are attached, said substituents being typically, independently of one another, selected in the group formed by, but not limited to: H, C1-C12 alkyl, C1-C12 haloalkyl, aryl, alkoxy and aryloxy. Examples of siloxy groups include, but are not limited to, trimethylsiloxy (-O-SiMe3) and triethylsiloxy (-O-SiEt3). In the context of the present invention, “unsaturated” means that the hydrocarbon chain may contain one or more unsaturation(s), i.e. a double bond C=C or a triple bond C≡C, advantageously one unsaturation. In the context of the present invention, "optionally substituted" means that the group in question is optionally substituted with one or more substituents which may be selected in particular from halogen, C₁-C₁₂ alkyl, C₁-C₁₂ haloalkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, aryl, - N₃, -NR^aR^b, -COR^c, -CO₂R^d, -CONR^eR^f, -OR^g, -SR^h, -OC(O)Rⁱ, -NC(O)R^j, -OC(O)NR^kR^l, -S(O)R^m, - PRⁿR^o, -BR^pR^q, -SiR^rR^sR^t, -OSiR^uR^vR^w, CN and NO_2, wherein R^a to R^m are, independently of one another, H, C1-C12 alkyl, C1-C12 haloalkyl, C2-C12 alkenyl, aryl or heteroaryl, and Rⁿ to R^w are, independently of one another, selected in the group formed by, but not limited to: H, C1- C12 alkyl, C1-C12 haloalkyl, aryl, C1-C12 alkoxy and aryloxy. Preferably, R^a to R^w is H or C1-C12 alkyl. The term “transition metal” refers to a chemical class of metallic atom including: scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, mercury, rutherfordium, dubnium, seaborgium, bohrium, hassium, meitnerium, darmstadtium, roentgenium and copernicium. The term “alkali metal” refers to another chemical class of metallic atoms including lithium, sodium, potassium, rubidium, cesium and francium. The term “alkaline earth metal” refers to the second-row metals of the periodic table: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). The term “salt” refers to a neutral chemical entity composed of an anion (negatively charged) and a cation (positively charged). Examples of salts include, but are not limited to, potassium tert-butoxide (tBuOK), sodium hydroxide (NaOH) or ammonium chloride (NH4Cl). In the context of the present invention, the notations « C(sp) », « C(sp²) » and « C(sp³) » refer to the hybridization of the atomic orbitals of the carbon atom, for example of the carbon atom in the C-H bond in question. The hybridization refers to the geometry of the atomic orbitals in which the valence electrons are distributed. When the carbon atom of the C-H bond is linked to a triple bond, i.e. ≡C-H, the carbon atom is said « sp ». When the carbon atom of the C-H bond is linked to a double bond, i.e. =C-H, the carbon atom is said « sp² ». When the carbon atom is linked to a simple bond, i.e. -C(R)-H (R optionally being H), the carbon atom is said « sp³ ». The hybridization of the carbon atom affects the ease with which the silylation of the C-H bond may occur. For example, in silylation methods of the state of the art, the intermolecular silylation of C(sp³)-H bonds is not possible or require high temperature-conditions to be achieved. Unless stated otherwise, the term “equivalent(s)” refers to molar equivalent(s). The method of the invention According to the present invention, there is provided a method for silylating an organic substrate comprising at least one silylatable C-H bond, said method comprising the step of reacting said organic substrate with a mixture comprising: (a) a silylated diazene of formula (I) wherein R is selected in the group consisting of C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, aryl, heteroaryl, heterocycloalkyl, C₃-C₇ cycloalkyl, Si(C₁-C₆alkyl)₃ and Si(O-C₁-C₆ alkyl)₃, said alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycloalkyl and cycloalkyl being optionally substituted, and R¹, R² and R³ are each independently selected in the group consisting of H, C1-C12 alkyl, C2- C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₁-C₁₂ alkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocycloalkyl, C₃-C₇ cycloalkyl, halogen and siloxy, said alkyl, alkenyl, alkynyl, alkoxy, aryl, aryloxy heteroaryl, heteroaryloxy, siloxy, heterocycloalkyl and cycloalkyl being optionally substituted, and (b) a catalyst. In particular, the method of the present invention is carried out under conditions sufficient to form the silylated compound. One of the main advantages of the present invention lies in the possibility to use various chemical classes of organic substrates to be silylated. Indeed, the methods and compositions of the invention are not limited to a particular class of activated substrates such as activated aromatic compounds as described in WO2014/055587 or terminal alkynes as described in WO2016/036685. In the present invention, the silylation of a C-H bond is notably possible whatever the carbon hybridization. Moreover, the present invention does not rely on a transition metal-based catalyst as described in WO2015/035325. The organic substrate comprising at least one silylatable C-H bond according to the present invention can be in the form of a stereoisomer or a mixture of stereoisomers, such as a mixture of enantiomers or diastereoisomers, notably a racemic mixture. The organic substrate comprising at least one silylatable C-H bond may be enriched with one or more isotope, such as deuterium (²H), tritium (³H),¹³C, ¹⁸F or ¹⁵N. Thus, according to some embodiments, the organic substrate comprising at least one silylatable C-H bond may be selected in the group consisting of optionally substituted arenes, optionally substituted heteroarenes, optionally substituted alkanes, optionally substituted alkenes and optionally substituted alkynes. In some specific embodiments, the organic substrate to be silylated by the method of the invention responds to one of the following formulae:

wherein • X is N–R’, O or S, • R’ is selected in the group consisting of C₁-C₁₂ alkyl, C₁-C₁₂ haloalkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, -C(O)O-C₁-C₁₂ alkyl, aryl, heteroaryl, heterocycloalkyl and cycloalkyl, said alkyl, haloalkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl or heterocycloalkyl being optionally substituted, • R⁵, R⁶, R⁷ and R⁸ are independently selected in the group consisting of H, halogen, aryl, heteroaryl, N₃, OH, CN, NO₂ and a C₁-C₁₂ aliphatic chain wherein one or more, preferably 1 to 4, methylene unit(s) is eventually replaced by -O-, -C(O)-, -N-, NR’’-, -S-, -S(O)-, -P-, -B- or -Si-, said aliphatic chain, aryl or heteroaryl being optionally substituted, or R⁵ and R⁶ or R⁶ and R⁷ or R⁷ and R⁸, together with the atoms to which they are bonded, form a fused aryl, heteroaryl, cycloalkyl or heterocycloalkyl, said aryl, heteroaryl, cycloalkyl and heterocycloalkyl being optionally substituted, • R⁹, R¹⁰, R¹¹, R¹², R¹³ and R¹⁴ are independently selected in the group consisting of H, halogen, aryl, heteroaryl, N₃, OH, CN, NO₂ and a C₁-C₁₂ aliphatic chain wherein one or more, preferably 1 to 4, methylene unit(s) is eventually replaced by -O-, -C(O)-, -N-, NR’’-, -S-, - S(O)-, -P-, -B- or -Si-, said aliphatic chain, aryl or heteroaryl being optionally substituted, or two or more of R⁹, R¹⁰, R¹¹, R¹², R¹³ and R¹⁴, together with the atoms to which they are bonded, form an aryl, a heteroaryl, a cycloalkyl or a heterocycloalkyl, said aryl, heteroaryl, cycloalkyl and heterocycloalkyl being optionally substituted, • R¹⁵ and R¹⁶ are independently selected in the group consisting of H, C₁-C₁₂ alkyl, C₁-C₁₂ haloalkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, heteroaryl, heterocycloalkyl and cycloalkyl, said alkyl, haloalkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl or heterocycloalkyl being optionally substituted, • R¹⁷ and R¹⁸ are independently selected in the group consisting of H, halogen, N3, oxo, OH, CN, NO2 and a C1-C12 aliphatic chain wherein one or more, preferably 1 to 4, methylene unit(s) is eventually replaced by -O-, -C(O)-, -N-, NR’’’-, -S-, -S(O)-, -P-, -B- or -Si-, said aliphatic chain being optionally substituted, or R¹⁷ and R¹⁸, together with the atom to which they are bonded, form a a cycloalkyl or a heterocycloalkyl, said cycloalkyl and heterocycloalkyl being optionally substituted, • R¹⁹ and R²⁰ are independently selected in the group consisting of H, halogen and a C1-C12 aliphatic chain wherein one or more, preferably 1 to 4, methylene unit(s) is eventually replaced by -O-, -C(O)-, -N-, NR’’’-, -S-, -S(O)-, -P-, -B- or -Si-, said aliphatic chain, being optionally substituted, and . R’’ is H, C1-C12 alkyl, C1-C12 haloalkyl, C2-C12 alkenyl, aryl or heteroaryl, said alkyl, haloalkyl, alkenyl, aryl or heteroaryl being optionally substituted, and . R’’’ is H, C1-C12 alkyl, C1-C12 haloalkyl, C2-C12 alkenyl or heteroaryl, said alkyl, haloalkyl, alkenyl or heteroaryl being optionally substituted. It is understood that substituents R⁵ to R²⁰ are defined so that the organic substrate of formula (II), (III), (IV) or (V) comprises at least one silylatable C-H bond. In a preferred embodiment, the organic substrate responds to the formula (II) : in which R⁵, R⁶, R⁷ and R⁸ are as defined above. In a specific embodiment, R⁵ is H and formula (II) is the following formula (II-A): wherein X is N-R’, O or S, R⁶, R⁷ and R⁸ are independently selected in the group consisting of H, halogen, aryl, heteroaryl, N3, oxo, OH, CN, NO2 and a C1-C12 aliphatic chain wherein one or more, preferably 1 to 4, methylene unit(s) is eventually replaced by -O-, -C(O)-, -N-, NR’’-, -S-, -S(O)-, -P-, - B- or -Si-, said aliphatic chain, aryl or heteroaryl being optionally substituted, R’ and R’’ being as defined above. Preferably, R⁶, R⁷ and R⁸ are independently selected in the group consisting of H, halogen, aryl, heteroaryl, N3, OH, CN, NO2 and a C1-C12 aliphatic chain wherein one or more, preferably 1 to 4, methylene unit(s) is eventually replaced by -O-, -C(O)-, -N-, NR’’- or -S-, R’’ being notably H or C₁-C₆ alkyl. In this embodiment, the 5-membered heteroaryl of formula (II-A) is preferably mono- substituted. In particular, R⁶ and R⁷ are H. When R⁶ and R⁷ are H, R⁸ is preferably a C1-C12 alkyl, in particular C1-C6 alkyl. More preferably, the 5-membered heteroaryl of formula (II-A) is unsubstituted, i.e. R⁶, R⁷ and R⁸ are H. When X is N-R’, R’ is typically selected in the group consisting of C1-C12 alkyl, C1-C12 alkenyl, aryl, heteroaryl or -C(O)-C1-C6 alkyl, said alkyl, alkenyl, aryl or heteroaryl being optionally substituted. In particular, R’ is a C1-C6 alkyl, such as methyl or aryl, such as phenyl, more preferably R’ is a methyl. The organic substrate of formula (II-A) may thus advantageously correspond to the following compounds: In another specific embodiment, R⁷ and R⁸ are H and formula (II) is the following formula (II- B): wherein X is N-R’, O or S, R⁵ and R⁶ taken together with the atoms to which they are bonded form a fused carbocyclyl, heterocycloalkyl, aryl or heteroaryl, said carbocyclyl, heterocycloalkyl, aryl and heteroaryl groups being optionally substituted, R’ is as defined above. In this embodiment, R⁵ and R⁶ taken together with the atoms to which they are bonded preferably form an aryl or heteroaryl, being optionally substituted by one or more halogen, aryl, C1-C12 alkyl, C1-C12 alkoxy group or C(O)OC1-C6alkyl. In particular, R⁵ and R⁶ taken together with the atoms to which they are bonded form an unsubstituted phenyl or a phenyl substituted with one halogen, C₁-C₁₂ alkyl, such as methyl, C₁-C₁₂ alcoxy group, such as methoxy, or C(O)OC1-C6alkyl, such as C(O)OMe. X is preferably N-R’, with R’ being preferably C1-C12 alkyl, such as methyl, C1-C12 alkenyl, such as 1-propenyl or allyl, cycloalkyl, such as cyclopentane, aryl, such as phenyl, or carbamate, such as a tert-butyloxycarbonyl. More preferably R’ is a C₁-C₁₂ alkyl, notably a methyl. The organic substrate of formula (II-B) may thus advantageously correspond to the following compounds: More preferably, the organic substrate is an optionally substituted N-substituted indole, notably an optionally substituted N-methyl indole. According to another specific embodiment, the organic substrate is a N-substituted indole optionally substituted on one or more of the intracyclic carbon atom(s) by a C1-C12 alkyl, such as methyl, a halogen or an aryl. According to this embodiment, the organic substrate may advantageously correspond to the following compound: According to another preferred embodiment, the organic substrate responds to the formula (III) : in which R⁹ to R¹⁴ are as defined above. Preferably, R⁹, R¹⁰, R¹¹, R¹², R¹³ and R¹⁴ are independently selected in the group consisting of H, halogen, aryl, heteroaryl, N3, OH, CN, NO2 and a C1-C12 aliphatic chain wherein one or more, preferably 1 to 4, methylene unit(s) is eventually replaced by -O-, -C(O)-, -N-, NR’’-, -S-, -S(O)-, -P-, -B- or -Si-, said aliphatic chain, aryl or heteroaryl being optionally substituted. In a preferred specific embodiment, one, two, three or four substituents among R⁹, R¹⁰, R¹¹, R¹², R¹³ and R¹⁴ is (are) selected in the group consisting of halogen, OH, C1-C12 alkyl, C1-C12 alkynyl, aryl, C1-C12 alkoxy, aryloxy, heteroaryloxy or OC(O)N(C1-C6alkyl)2. In particular, the organic substrate of formula (III) may advantageously correspond to the following compounds:

According to another preferred embodiment, the organic substrate responds to the following formula (IV): in which R¹⁵ and R¹⁶ are as defined above. In this embodiment, R¹⁵ is preferably H and R¹⁶ is preferably an optionally substituted C1-C12 alkyl. In particular, the organic substrate of formula (IV) may advantageously correspond to the following compounds: According to another preferred embodiment, the organic substrate responds to the following formula (V): in which R¹⁷ R¹⁸, R¹⁹ and R²⁰ are as defined above. Preferably, R¹⁷ and R¹⁸ are independently selected in the group consisting of H, halogen, N₃, oxo, OH, CN, NO₂ and a C₁-C₁₂ alkyl wherein one or more, preferably 1 to 4, methylene unit(s) is eventually replaced by -O-, -C(O)-, -N-, NR’’’-, -S-, -S(O)-, -P-, -B- or -Si-, said alkyl being optionally substituted, or R¹⁷ and R¹⁸, together with the atom to which they are bonded, form a a cycloalkyl or a heterocycloalkyl, said cycloalkyl and heterocycloalkyl being optionally substituted. More preferably, R¹⁷ and R¹⁸, together with the atom to which they are bonded, form a cycloalkyl or a heterocycloalkyl, said cycloalkyl and heterocycloalkyl being optionally substituted. Preferably, R¹⁹ and R²⁰ are independently selected in the group consisting of H, halogen and a C1-C12 alkyl wherein one or more, preferably 1 to 4, methylene unit(s) is eventually replaced by -O-, -C(O)-, -N-, NR’’’-, -S-, -S(O)-, -P-, -B- or -Si-, said alkyl being optionally substituted. In particular, the organic substrate of formula (V) may advantageously correspond to the following compound: In some embodiments, in the silylated diazene of formula (I): (I), R is preferably selected in the group consisting of C₁-C₆ alkyl and aryl. More preferably, R is C₁-C₆ alkyl notably a methyl, an ethyl, a propyl or a tert-butyl, in particular a tert-butyl. R¹, R² and R³ are preferably each independently selected in the group consisting of H, C1-C6 alkyl, C1-C6 alkoxy and aryl, more preferably in the group consisting of H, C1-C6 alkyl and aryl. In particular, R¹, R² and R³ are each independently H, a methyl, an ethyl, an isopropyl, a tert-butyl or a phenyl group. According to a particular embodiment, R¹, R² and R³ may be identical. In particular, the silylated diazene of formula (I) may be advantageously chosen among the following compounds: The silylated diazenes of formula (I) are typically obtained by oxidation of the corresponding silylated hydrazines, according to methods well-known from the skilled person (see Chauvier et al., Organometallics, 2019, 38, 4679). The silyl group introduced into the organic substrate corresponds to the group SiR¹R²R³ as defined above. In some embodiments, the catalyst used in the present invention is a Lewis basic species, including, but not limited to, organic and metal salts or mixture thereof. In particular, the catalyst is a salt of an ammonium, a phosphonium, an alkali metal, an alkaline earth metal or mixtures thereof, notably an alkali or alkali earth metal alkoxide, aryloxide or fluoride. Preferably, the catalyst is a lithium-salt, a sodium-salt, a potassium-salt, a cesium-salt or mixtures thereof, in particular a sodium salt or a potassium salt. For example, the catalyst is selected in the group consisting of tBuOLi, tBuOK, tBuONa, Me₃SiOK, Me₃SiONa, KOH, CsF and mixtures thereof. More preferentially, the catalyst is tBuOK or Me3SiOK According to a preferred embodiment, the catalyst is a transition metal-free catalyst. Indeed, the reaction operates well in the complete absence of transition metal-based complexes. Likewise, the method is also operable in the absence or substantially complete absence of other electromagnetic or thermal triggers needed for initiation or propagation reactions. That is, these embodiments do not need UV irradiation or electric or plasma discharge conditions to operate. The mixture optionally comprises one or more additives. The additive refers to any component able to improve the selectivity and/or the kinetic of the silylation reaction. In particular, the additives may be compounds or ligands able to coordinate the metal ions of the catalyst so as to improve the selectivity and/or the kinetic of the reaction. According to preferred embodiments, the mixture involved in the reaction of the present invention may comprise additives selected in the group consisting of crown ethers such as 18-crown-6, cryptands, polyamino compounds such as N,N,N’,N’-tetramethylenediamine (TMEDA) and nitrogen heterocycles such as pyridine, bipyridine or phenantroline. The additive is typically in an amount from 1 equivalent to 3 equivalents relative to the catalyst. The conditions sufficient to form the silylated compound according to the method of the present invention notably include the solvent, the reaction time, the atmosphere of the reaction medium, the temperature of the reaction medium and the quantity of each component involved in the reaction, each feature being set up so as to form the silylated compound. These features depend on the nature of the organic substrate to be silylated, the nature of the silylated diazene and the catalyst used in the reaction. The skilled person is able to set up each feature in order to obtain the optimal conditions to achieve the method of the present invention. The reaction is typically carried out in a solvent selected among aprotic solvents such as hexane, tetrahydrofuran (THF), diethylether (Et₂O) or dimethoxyethane (DME). An aprotic solvent will not compete with the organic substrate for deprotonation. In another embodiment, the reaction can optionally be carried in the absence of solvent when the substrate is a liquid under the temperature and pressure conditions of the reaction. The reaction is preferably carried out at ambient temperature, i.e. between 18 °C and 40 °C, notably between 18 °C and 25 °C. The reaction is preferably carried out under inert atmosphere such as nitrogen (N₂) or argon (Ar) atmosphere. The mixture is substantially free of a transition-metal compound, or where present, the transition metal may be considered as a spectator to the reaction. The term "substantially free of a transition-metal compound" is defined to reflect that the total level of transition metal within the composition, independently or in the presence of organic substrate, is less than about 5 ppm, as measured by ICP-MS. According to preferred embodiments, the reaction is carried out until full conversion of the organic substrate is observed as can be inferred from the monitoring of the reaction by TLC (Thin Layer Chromatography), NMR spectroscopy or gas chromatography (GC). Typically, the reaction is carried out for a time of less than 24 hours, in particular less than 18h, in particular less than 6 hours, in particular less than 3 hours, in particular less than 2 hours. Preferably, the time reaction is comprised between 5 min and 2 hours, preferably between 30 min and 90 min. Indeed, one of the advantages of the method of the invention is that the maximum conversion rate is generally obtained in a short time, i.e. in less than 2 hours. The reaction of the present invention is thermodynamically favorable due to the liberation of dinitrogen which drives the reaction to the formation of the expected silylated compound. Th diazene of formula (I) is typically used in the method of the invention in a stochiometric quantity or in excess relative to the organic substrate comprising at least one silylatable C- H bond. In particular, the diazene of formula (I) is used in an amount from 1 equivalent to 6 equivalents relative to the organic substrate, preferably from 1 equivalent to 3 equivalents, more preferably from 1 equivalent to 2 equivalents, even more preferably from 1 equivalent to 1.5 equivalents, more preferably at 1.2 or 1.3 equivalents. The amount of the diazene of formula (I) may be function of the number of the C-H bonds to be silylated on the organic substrate. According to some embodiments, the number of equivalents of the diazene of formula (I) will be equal to or in slight excess of the number of C-H bonds to be silylated. Typically, when there is one C-H bond to be silylated, the diazene of formula (I) is preferably used in an amount from 1 to 2, notably from 1 to 1.5 equivalents. When there are two C-H bonds to be silylated, the diazene of formula (I) is preferably used in an amount from 2 to 3.5, notably from 2 to 2.5 equivalents. The catalyst is typically used in substoichiometric quantities. In other terms, the catalyst is typically used in an amount comprised from 1 mol% to 30 mol%, preferably from 5 mol% to 20 mol%, more preferably from 5 mol% to 15 mol%, in particular at 10 mol%, with respect to the amount of the organic substrate comprising at least one silylatable C-H bond. The amount of catalyst used in the reaction may also be function of the number of C-H bonds to be silylated on the organic substrate. When there is more than one C-H bonds to be silylated, the amount of the catalyst therefore may be adapted accordingly by the skilled person in the art. When the organic substrate to be silylated according to the method of the present invention comprises more than one silylatable C-H bond, the silylation may thus occur for only one C- H bond, for a part of the C-H bonds or for the whole C-H bonds present on the substrate. In this respect, the number of C–H bonds that will be silylated according to the method of the present invention will primarily depend on the amount of the diazene of formula (I). One or more C-H bonds of the organic substrate may be regioselectively silylated due to the optional presence of a directing group or heteroatom on the organic substrate. In particular, the organic substrate may comprise alpha-, beta- or gamma-directing group or heteroatom that causes the silylation to occur for the C-H bonds located in the alpha, beta or gamma position of the directing group. The alpha position refers to the position directly adjacent to the directing group. The beta position refers to the second position adjacent to the directing group. The gamma position refers to the third position adjacent to the directing group. In a 6-membered arene, the positions alpha and beta are respectively called ortho and meta. In a 6-membered arene, the position gamma is called para. A directing group may be either ortho-, meta- or para-directing or it can be both ortho- and para-directing. As a consequence, the regioselectivity of the silylation primarily depends on the amount of diazene of formula (I) and on the presence and the nature of the directing group or atom. When the organic substrate includes an intracyclic heteroatom, i.e. when the organic substrate is a heteroarene, the heteroatom being optionally substituted, the silylation preferably occurs regioselectively on the C-H bond located at the alpha position with respect to the heteroatom. The method of the present invention typically comprises the following steps: (i) preparing a silylated diazene of formula (I) as defined above by oxidation of the corresponding hydrazine, (ii) reacting an organic substrate comprising at least one silylatable C-H bond as defined above, with a mixture comprising said silylated diazene of formula (I) and a catalyst, under conditions appropriate to form the silylated compound. Advantageously, step (ii) is achieved in presence of a solvent, notably an aprotic solvent. Preferably, step (ii) comprises the following sub-steps: (ii-1) charging a reactor with a reaction medium comprising the organic substrate comprising at least one silylatable C-H bond, and a solvent, (ii-2) adding to the reaction medium the catalyst, (ii-3) adding to the reaction medium the diazene of formula (I), (iii-4) recovering the silylated compound. According to some embodiments, step (ii-2) may be carried out concomitantly with step (ii- 1) or with step (ii-3), or step (ii-2) may be carried out after step (ii-3). According to a preferred embodiment, the reaction medium is stirred during the implementation of the method. The diazene of formula (I) is preferably added dropwise to the reaction medium. The recovering of the silylated compound may include a purification step. Such a purification step may be carried out by methods well known to the person skilled in the art, such as by recrystallisation, by distillation, by chromatography on a column of silica gel or by high performance liquid chromatography (HPLC). The present invention also relates to a method for silylating an organic substrate comprising at least one silylatable C-H bond, said method comprising the step of reacting said organic substrate with a mixture comprising: (a) a silylated diazene of formula (I) as defined above, (b) a catalyst. Said method is notably carried out under conditions appropriate to form a silylated compound, as defined above. The composition of the invention According to the present invention, there is provided a composition for silylating an organic substrate comprising at least one silylatable C-H bond, said composition comprising: (a) a silylated diazene of formula (I) wherein R is selected in the group consisting of C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, heteroaryl, heterocycloalkyl, C₃-C₇ cycloalkyl, Si(C₁-C₆alkyl)₃ and Si(O-C₁-C₆ alkyl)₃, said alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycloalkyl and cycloalkyl being optionally substituted, and R¹, R² and R³ are each independently selected in the group consisting of H, C₁-C₁₂ alkyl, C₂- C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₁-C₁₂ alcoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocycloalkyl, C3-C7 cycloalkyl, halogen and siloxy, said alkyl, alkenyl, alkynyl, alcoxy, aryl, aryloxy heteroaryl, heteroaryloxy, siloxy, heterocycloalkyl and cycloalkyl being optionally substituted, (b) a catalyst and (c) an organic substrate comprising at least one silylatable C-H bond. All the features described above for the method of silylation of the present invention, notably those regarding the definition of the organic substrate, the silylated diazene of formula (I) and the catalyst are also relevant for the composition for silylating said organic substrate according to the invention, provided that R in formula (I) is not an aryl. The composition according to the invention may be implemented in the method of the invention for silylating an organic substrate comprising at least one silylatable C-H bond. Preferably, the composition for silylating an organic substrate is substantially free of a transition-metal compound, or where present, the transition metal may be considered as a spectator to the reaction. According to some embodiments, the composition comprises one or more additives as defined above. The composition also typically includes a solvent suitable for the implementation of the silylation of the organic substrate. The present invention also relates to a composition comprising: (a’) a silylated compound, (b’) at least one impurity resulting from the reaction of an organic substrate comprising at least one silylatable C-H bond with a mixture comprising: - a silylated diazene of formula (I) wherein R is selected in the group consisting of C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, aryl, heteroaryl, heterocycloalkyl, C₃-C₇ cycloalkyl, Si(C₁-C₆alkyl)₃ and Si(O-C₁-C₆ alkyl)₃, said alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycloalkyl and cycloalkyl being optionally substituted, and R¹, R² and R³ are each independently selected in the group consisting of H, C1-C12 alkyl, C2- C12 alkenyl, C2-C12 alkynyl, C1-C12 alcoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocycloalkyl, C3-C7 cycloalkyl, halogen and siloxy, said alkyl, alkenyl, alkynyl, alcoxy, aryl, aryloxy heteroaryl, heteroaryloxy, siloxy, heterocycloalkyl and cycloalkyl being optionally substituted, and - a catalyst. In particular, the at least one impurity resulting from the reaction of an organic substrate comprising at least one silylatable C-H bond with a mixture comprising a silylated diazene of formula (I) as defined above and a catalyst is selected among the following compounds: in which R, R¹, R² and R³ are as defined above. All the features described above for the definition of the organic substrate, the silylated diazene of formula (I) and the catalyst are also relevant for this composition. In compounds of formula A, B, C, D or E, R is preferably selected in the group consisting of C1-C6 alkyl and aryl. More preferably, R is C1-C6 alkyl notably a methyl, an ethyl, a propyl or a tert-butyl, in particular a tert-butyl. In compounds of formula A, B, C, D or E, R¹, R² and R³ are preferably each independently selected in the group consisting of H, C₁-C₆ alkyl, C₁-C₆ alkoxy and aryl, more preferably in the group consisting of H, C1-C6 alkyl and aryl. In particular, R¹, R² and R³ are each independently H, a methyl, an ethyl, an isopropyl, a tert-butyl or a phenyl group. R¹, R² and R³ are preferably identical. According to preferred embodiment, the at least one impurity is found in traces amount in the composition. The term “traces amount” refers, in the context of the present invention, to an amount of said impurity of less than 10 mol%, preferably less than 1mol%, relative to the amount of diazene introduced, as measured by gas chromatography (GC), High Performance Liquid chromatography (HPLC) or mass spectrometry (MS), in particular GC-MS or LC-MS. Preferably, this composition is substantially free of a transition-metal compound. The composition may further comprise a compound of formula R-H, in which R is as defined above. In case the compound of formula R-H is in the form of a gas, it may be hardly detectable under conventional methods such as GC, or GC-MS, unless the reactor containing the said composition has not been vented. . According to some embodiments, the composition comprises one or more additives as defined above. The composition also typically includes a solvent suitable for the implementation of the silylation of the organic substrate. The following examples are provided to illustrate some of the concepts described within this disclosure. While each example is considered to provide specific individual embodiments of composition, methods of preparation of the compounds and methods for silylating an organic substrate, none of the examples should be considered to limit the scope of the present invention. EXAMPLES 1. General information Reactions were performed in flame-dried glassware using an MBraun glove box (O2 < 0.1 ppm, H₂O < 1.0 ppm) or conventional Schlenk techniques under a static pressure of argon unless otherwise stated. Glassware for reactions was flame-dried under vacuum prior to use. Liquids and solutions were transferred with syringes. All stated temperatures refer to external temperatures. Tetrahydrofuran (THF) was dried over sodium/benzophenone, thermally distilled, degassed with three freeze-pump-thaw cycles and stored in a glove box over thermally activated 4 Å molecular sieves (MS). n-Pentane was obtained from Aldrich and degassed by argon bubbling (> 30 min) prior to use. Standard solvents and reagents were obtained from Fluorochem, Acros, Alfa Aesar, Sigma-Aldrich or Tokyo Chemical Industry (TCI). Me₃SiOK (Aldrich) as well as tBuOLi, tBuONa (Aldrich) and tBuOK (Aldrich) were sublimed under high vacuum prior to use. Flash column chromatography was performed on Silica 60 M (40–63 μm, Macherey Nagel) silica gel. Technical grade solvents were distilled prior to use. TLC analyses were performed on Merck 60 F₂₅₄ silica gel pre-coated aluminum- backed plates with a layer thickness of 200 μm. Product spots were visualized under UV light (λmax = 254 nm) and/or by staining with a potassium permanganate solution. ¹H, ¹³C, ²⁹Si and ¹⁹F NMR spectra were recorded on Bruker AV300 and AV400 instruments. CDCl3 and CD2Cl2 were purchased from Eurisotop and used as received. THF-d8 (Eurisotop or Sigma-Aldrich) was degassed and stored over activated 4 Å molecular sieves prior to use. Chemical shifts are reported in parts per million (ppm) and are referenced to the residual solvent signals as the internal standard (CDCl₃: δ = 7.26 ppm, CD₂Cl₂: δ = 5.32 ppm for ¹H NMR and CDCl₃: δ = 77.16 ppm, CD₂Cl₂ δ = 53.84 ppm for ¹³C NMR). Data are reported as follows: chemical shift, multiplicity (s = singlet, d = doublet, dd = doublet of doublets, dt = doublet of triplets, t = triplet, tt = triplet of triplets, q = quartet, hept = heptuplet, m = multiplet, b = broad), coupling constants (Hz) and integration.²⁹Si and ¹⁹F NMR spectra were calibrated according to the IUPAC recommendation using a unified chemical shift scale based on the proton resonance of tetramethylsilane as primary reference. Melting points (m.p.) were determined with a Stuart Scientific SMP3 melting point apparatus and are not corrected. High resolution mass spectrometry (HRMS) analyses were obtained using a mass spectrometer MicroTOF from Bruker with an electron spray ion source (ESI) and a TOF detector at the Institut Parisien de Chimie Moléculaire (Sorbonne Université). Compound names were generated by the computer program ChemDraw according to the guidelines specified by the International Union of Pure and Applied Chemistry (IUPAC). 2. Synthesis and characterization of N-tert-butyl-N’-silyldiazenes 2.1. General procedures GP1 (N-tert-butyl-N’-silylhydrazine synthesis): A flame-dried, two-necked round-bottomed flask equipped with a stirring bar and a rubber septum was charged with finely ground tert- butylhydrazine hydrochloride (1 eq.) and was rapidly evacuated under vacuum. THF (0.7 M) was then added by syringe under argon followed by DBU (2.1 eq). The resulting white suspension was vigorously stirred and the chlorosilane (1.1 eq) was then added dropwise at room temperature. The reaction mixture was further stirred for 18 h unless otherwise indicated. The crude suspension was quickly filtered under air and the solid washed with THF (20 – 40 mL). The filtrate, which was collected in a Schlenk flask, was concentrated in vacuo by rotary evaporation affording the crude hydrazine. Although the purity (checked by ¹H and ²⁹Si NMR) of the latter is generally high enough to be engaged without further purification in the next oxidation step, the hydrazine may be isolated in pure form by distillation or vacuum-transfer (exemplified for 1a_Hy (SiMe₃) and 1b_Hy (SiEt₃)). GP2 (Oxidation from the unpurified N-tert-butyl-N’-silylhydrazine): To the Schlenk flask containing the crude hydrazine was added n-pentane (98%, degassed by argon bubbling, 0.6 M). To this solution was added di-tert-butyl azodicarboxylate (1.0 eq, assuming 100% yield of N-tert-butyl-N’-silylhydrazine) in one portion as a solid by quickly removing the rubber septum under a flow of argon. The resulting orange suspension was vigorously stirred at RT for the indicated time after which the reaction mixture was deep red. The solvent was removed in vacuo by rotary evaporation to afford a solid residue. The diazene was then isolated by vacuum transfer either under static or dynamic vacuum. GP3 (Oxidation of the pure N-tert-butyl-N’-silylhydrazine): A flame-dried, one-necked round-bottomed Schlenk flask equipped with a stirring bar was charged with the N-tert- butyl-N’-silylhydrazine (1 eq) and diluted with n-pentane (98%, degassed by argon bubbling, 0.6 M). To this colorless solution was added di-tert-butyl azodicarboxylate (1.0 eq) in one portion as a solid by quickly removing the rubber septum under a flow of argon. The resulting orange suspension was vigorously stirred 1 – 2 h at room temperature after which time the reaction mixture was deep red indicating the formation of the corresponding diazene. The solvent was removed in vacuo by rotary evaporation to afford an oily residue. The diazene was then isolated from the residue by vacuum transfer either under static or dynamic vacuum. 2.2. Characterization data 1-(tert-butyl)-2-(trimethylsilyl)hydrazine (1a_Hy) Prepared according to GP1 from tert-butylhydrazine hydrochloride (3.12 g, 25 mmol, 1.0 eq.), DBU (7.9 mL, 52.5 mmol, 2.1 eq) and Me3SiCl (3.5 mL, 27.5 mmol, 1.1 eq). Careful removal of THF in vacuo afforded the crude title compound that was purified by static vacuum transfer and obtained as a colorless liquid (1a_Hy, 2.66 g, 16.6 mmol, 66%). ¹H NMR (400 MHz, CDCl₃): δ/ppm = 2.57 (bs, 1H, NH), 2.43 (bs, 1H, NH), 1.00 (s, 9H), 0.03 (s, 9H).¹³C{¹H} NMR (75 MHz, CDCl₃): δ/ppm = 68.1, 27.0, ‐0.7. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 0.03/2.9. HRMS (APCI) m/z: [M+H]⁺ Calcd for C7H20N2SiH: 161.1469; Found 161.1468. 1-(tert-butyl)-2-(triethylsilyl)hydrazine (1bHy) Prepared according to GP1 from tert-butylhydrazine hydrochloride (2.80 g, 22.5 mmol, 1.0 eq.), DBU (7.1 mL, 47.3 mmol, 2.1 eq) and Et3SiCl (4.2 mL, 24.8 mmol, 1.1 eq). Removal of THF in vacuo afforded the crude title compound that was purified by dynamic vacuum transfer and obtained as a colorless liquid (1bHy, 3.30 g, 16.3 mmol, 72%). ¹H NMR (400 MHz, CDCl₃): δ/ppm = 2.52 (bs, 1H), 2.46 (bs, 1H), 1.00 (s, 9H), 0.94 (t, J = 7.9 Hz, 9H), 0.55 (q, J = 7.9 Hz, 6H).¹³C{¹H} NMR (75 MHz, CDCl₃): δ/ppm = 53.4, 27.0, 7.4, 4.1. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 0.94/7.2. HRMS (APCI) m/z: [M+H]⁺ Calcd. for C10H26N2SiH: 203.1938; Found: 203.1937. 1-(tert-butyl)-2-(tert-butyldimethylsilyl)hydrazine (1cHy) Prepared according to GP1 from tert-butylhydrazine hydrochloride (2.86 g, 23.0 mmol, 1.0 eq.), DBU (7.2 mL, 48.3 mmol, 2.1 eq) and tBuMe₂SiCl (4.3 mL, 24.2 mmol, 1.05 eq). Removal of THF in vacuo afforded the crude title compound that was used in the next oxidation step without further purification. Key spectroscopic resonances: ¹H NMR (400 MHz, CDCl3): δ/ppm = 2.52 (bs, 1H), 2.45 (bs, 1H), 0.99 (s, 9H), 0.89 (s, 9H), -0.01 (s, 9H).¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 0.89/7.6. 1-(tert-butyl)-2-(diisopropylsilyl)hydrazine (1d_Hy) Prepared according to GP1 from tert-butylhydrazine hydrochloride (1.24 g, 10.0 mmol, 1.0 eq.), DBU (3.1 mL, 21 mmol, 2.1 eq) and iPr2SiHCl (2.0 mL, 12 mmol, 1.2 eq). Removal of THF in vacuo afforded the crude title compound that was used in the next oxidation step without further purification. Key spectroscopic resonances: ¹H NMR (300 MHz, CDCl3): δ/ppm = 3.96 (q, J = 1.7 Hz, 1H, SiH). ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl3): δ/ppm = 3.96/4.7. 1-(tert-butyl)-2-(phenyldimethylsilyl)hydrazine (1eHy) Prepared according to GP1 from tert-butylhydrazine hydrochloride (0.62 g, 5.0 mmol, 1.0 eq.), DBU (1.6 mL, 10.5 mmol, 2.1 eq) and PhMe₂SiCl (0.9 mL, 5.5 mmol, 1.1 eq). Removal of THF in vacuo afforded the crude title compound that was used in the next oxidation step without further purification. Key spectroscopic resonances: ¹H NMR (300 MHz, CDCl3): δ/ppm = 1.00 (s, 9H), 0.31 (s, 6H). ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl₃): δ/ppm = 0.31/–4.3. 1-(tert-butyl)-2-(trimethylsilyl)diazene (1a) Prepared according to GP3 from purified 1aHy (2.64 g, 16.5 mmol, 1.0 eq.) and DBAD (3.80 g, 16.5 mmol, 1 eq). Careful removal of n-pentane in vacuo followed by static vacuum transfer afforded the title compound as a deep red liquid (1a, 2.20 g, 13.9 mmol, 84%). When GP2 was followed, the title compound was obtained in 61 % yield over 2 steps. ¹H NMR (300 MHz, CDCl3): δ/ppm = 1.15 (s, 9H), 0.24 (s, 9H).¹³C{¹H} NMR (75 MHz, CDCl3): δ/ppm = 73.8, 26.0, ‐2.7. ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl3): δ/ppm = 0.24/9.4. HRMS (APCI) m/z: [M+H]⁺ Calcd for C7H18N2SiH: 159.1312; Found: 159.1312. 1-(tert-butyl)-2-(triethylsilyl)diazene (1b) Prepared according to GP3 from purified 1bHy (3.28 g, 16.2 mmol, 1.0 eq.) and DBAD (3.73 g, 16.5 mmol, 1 eq). Careful removal of n-pentane in vacuo followed by dynamic vacuum transfer afforded the title compound as a deep red liquid (1b, 2.70 g, 13.5 mmol, 83%). When GP2 was followed, the title compound was obtained in 62 % yield over 2 steps. ¹H NMR (300 MHz, CDCl₃): δ/ppm = 1.15 (s, 9H), 1.01 – 0.87 (m, 9H), 0.85 – 0.70 (m, 6H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ/ppm = 74.4, 26.1, 6.8, 2.8.¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl3): δ/ppm = 0.91/9.7. HRMS (APCI) m/z: [M+H]⁺ Calcd for C10H24N2SiH: 201.1782; Found: 201.1782. 1-(tert-butyl)-2-(tert-butyldimethylsilyl)diazene (1c) Prepared according to GP2 from unpurified 1cHy (4.15 g, 19.5 mmol, 1.0 eq.) and DBAD (4.49 g, 19.5 mmol, 1 eq). Careful removal of n-pentane in vacuo followed by static vacuum transfer afforded the title compound as a deep red liquid (1c, 3.34 g, 16.7 mmol, 85%). ¹H NMR (300 MHz, CDCl₃): δ/ppm = 1.15 (s, 9H), 0.96 (s, 9H), 0.16 (s, 6H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ/ppm = 74.3, 26.18, 26.13, 17.7, ‐7.3.¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl₃): δ/ppm = 0.96/10.7. HRMS (APCI) m/z: [M+H]⁺ Calcd for C₁₀H₂₄N₂SiH: 201.1782; Found: 201.1782. 1-(tert-butyl)-2-(diisopropylsilyl)diazene (1d) Prepared according to GP2 from unpurified 1d_Hy (2.02 g, 10.0 mmol, 1.0 eq.) and DBAD (2.30 g, 10.0 mmol, 1 eq). Careful removal of n-pentane in vacuo followed by dynamic vacuum transfer afforded the title compound as a deep red liquid (1d, 0.70 g, 3.49 mmol, 35% over 2 steps). ¹H NMR (300 MHz, CDCl₃): δ/ppm = 4.13 (t, J = 2.7 Hz, 1H, SiH), 1.45 – 1.22 (m, 2H, CH(CH₃)₂, 2H), 1.19 (s, 9H, (CH₃)₃), 1.06 (dd, J = 14.0, 7.4 Hz, 12H, CH(CH₃)₂). ¹³C{¹H} NMR (75 MHz, CDCl3): δ/ppm = 75.4, 26.2, 17.8, 10.9. ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl3): δ/ppm = 1.07/8.6. HRMS (APCI) m/z: [M+H]⁺ Calcd for C10H24N2SiH: 201.1782; Found: 201.1782. 1-(tert-butyl)-2-(dimethylphenyl)diazene (1e) Prepared according to GP2 from unpurified 1e_Hy (1.11 g, 5.0 mmol, 1.0 eq.) and DBAD (1.15 g, 5.0 mmol, 1 eq). Removal of n-pentane in vacuo afforded the crude title compound that was purified by dynamic vacuum transfer and obtained as a deep red liquid (1e, 0.44 g, 2.02 mmol, 40% over 2 steps). ¹H NMR (400 MHz, CDCl₃): δ/ppm = 7.66 – 7.58 (m, 2H), 7.45 – 7.34 (m, 3H), 1.18 (s, 9H), 0.48 (s, 6H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ/ppm = 136.1, 134.4, 129.8, 128.0, 74.6, 26.1, -3.9.¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 0.48/–1.8. HRMS (APCI) m/z: [M+H]⁺ Calcd for C12H20N2SiH: 221.1469; Found: 221.1469. 3. Synthesis and characterization of silylated products 3.1. General procedure GP4: A 10-mL vial equipped with a magnetic stirring bar was charged with potassium tert- butoxide (tBuOK, 10 mol%, 5.6 mg, 0.1 eq), THF (2.5 mL) and the corresponding substrate (0.5 mmol, prior to adding the solvent when solid). To the resulting vigorously stirred mixture was then added dropwise a solution of the silylated tert-butyldiazene (0.6 mmol, 1.2 eq) in THF (1 mL) at room temperature. When full conversion of the substrate was reached (usually < 5 min reaction time as judged by TLC or ¹H NMR analysis but the reactions were generally left stirring ca. 1 h), the crude mixture was concentrated by rotary evaporation and the resulting crude residue was directly purified by flash column chromatography on silica gel. 3.2. Characterization data 1-methyl-2-(trimethylsilyl)-1H-indole (2a) Prepared according to GP4 from the corresponding diazene 1a (95 mg, 0.60 mmol, 1.2 eq.) and 1-methyl-1H‐indole (62 μL, 0.50 mmol, 1.0 eq). Full conversion of the indole was reached within 1 h. Purification by flash column chromatography on silica gel using petroleum ether (100 %) as eluent afforded the title compound 2a (74.0 mg, 0.36 mmol, 73 %) as a colorless oil. R_f = 0.20 petroleum ether (100 %). ¹H NMR (300 MHz, CDCl₃): δ/ppm = 7.66 (dt, J = 7.9, 1.0 Hz, 1H), 7.38 (dt, J = 8.3, 1.0 Hz, 1H), 7.33 – 7.21 (m, 1H), 7.13 (ddd, J = 7.9, 6.9, 1.1 Hz, 1H), 6.75 (d, J = 0.9 Hz, 1H), 3.91 (s, 3H), 0.45 (s, 9H).¹³C{¹H} NMR (75 MHz, CDCl3): δ/ppm = 141.2, 140.3, 128.5, 122.1, 120.8, 119.3, 111.5, 109.1, 33.1, -0.4. ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl3): δ/ppm = 0.45/‐10.8. The spectroscopic data match the literature report.¹⁵ 1-methyl-2-(triethylsilyl)-1H-indole (2b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 eq.) and 1-methyl-1H‐indole (62 μL, 0.50 mmol, 1.0 eq). Full conversion of the indole was reached within 1 h. Purification by flash column chromatography on silica gel using petroleum ether:EtOAc (99:1) as eluent afforded the title compound 2b (110 mg, 0.45 mmol, 90 %) as a yellow oil. ¹H NMR (300 MHz, CDCl₃): δ/ppm = 7.64 (dt, J = 7.8, 1.0 Hz, 1H), 7.35 (dt, J = 8.2, 0.9 Hz, 1H), 7.24 (ddd, J = 8.1, 6.9, 1.2 Hz, 1H), 7.11 (ddd, J = 7.9, 6.9, 1.1 Hz, 1H), 6.75 (d, J = 0.9 Hz, 1H), 3.86 (s, 3H), 1.10 – 1.00 (m, 9H), 0.99 – 0.87 (m, 6H). ¹³C{¹H} NMR (75 MHz, CDCl3): δ/ppm = 140.3, 138.4, 128.7, 122.0, 120.7, 119.1, 113.1, 109.1, 33.1, 7.7, 4.1. ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl₃): δ/ppm = 0.91/‐2.4. The spectroscopic data match the literature report.⁷ 1-methyl-2-(tertbutyldimethylsilyl)-1H-indole (2c) Prepared according to GP4 from the corresponding diazene 1c (120 mg, 0.60 mmol, 1.2 eq.) and 1-methyl-1H‐indole (62 μL, 0.50 mmol, 1.0 eq). Full conversion of the indole was reached within 1 h. Purification by flash column chromatography on silica gel using petroleum ether (100 %) as eluent afforded the title compound 2c (92.0 mg, 0.38 mmol, 75 %) as a colorless oil. Rf = 0.23 petroleum ether (100 %). ¹H NMR (400 MHz, CDCl3): δ/ppm = 7.61 (dt, J = 7.9, 1.0 Hz, 1H), 7.33 (dd, J = 8.4, 1.2 Hz, 1H), 7.22 (ddd, J = 8.2, 7.0, 1.1 Hz, 1H), 7.09 (ddd, J = 7.9, 6.9, 1.0 Hz, 1H), 6.73 (d, J = 0.9 Hz, 1H), 3.85 (s, 3H), 0.96 (s, 9H), 0.40 (s, 6H).¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 140.4, 139.1, 128.5, 122.1, 120.7, 119.3, 113.4, 109.3, 33.8, 27.0, 17.7, –4.1.¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 0.40/–2.0. HRMS (APCI) m/z: [M+H]⁺ Calcd for C15H23NSiH: 246.1673; Found: 246.1672. 1-methyl-2-(diisopropylsilyl)-1H-indole (2d) Prepared according to GP4 from the corresponding diazene 1d (120 mg, 0.60 mmol, 1.2 eq.) and 1-methyl-1H‐indole (62 μL, 0.50 mmol, 1.0 eq). Full conversion of the indole was reached within 1 h. Purification by flash column chromatography on silica gel using petroleum ether (100 %) as eluent afforded the title compound 2d (103 mg, 0.38 mmol, 84 %) as a colorless liquid. R_f = 0.32 petroleum ether (100 %). ¹H NMR (400 MHz, CDCl₃): δ/ppm = 7.64 (dt, J = 7.9, 1.0 Hz, 1H), 7.35 (dd, J = 8.3, 1.2 Hz, 1H), 7.25 – 7.21 (m, 1H), 7.10 (ddd, J = 8.0, 7.0, 1.0 Hz, 1H), 6.76 (d, J = 0.9 Hz, 1H), 4.21 (t, J = 3.4 Hz, 1H), 3.87 (s, 3H), 1.31 (dtd, J = 14.5, 7.3, 3.4 Hz, 2H), 1.18 – 1.01 (m, 12H).¹³C{¹H} NMR (101 MHz, CDCl3): δ/ppm = 140.1, 135.5, 128.7, 122.1, 120.7, 119.3, 113.3, 109.4, 33.1, 19.0, 18.9, 11.3.¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 4.21/–7.7. HRMS (APCI) m/z: [M+H]⁺ Calcd for C₁₅H₂₃NSiH: 246.1673; Found: 246.1673. 1-methyl-2-(phenyldimethylsilyl)-1H-indole (2e) Prepared according to GP4 from the corresponding diazene 1e (120 mg, 0.80 mmol, 2.0 eq.) and 1-methyl-1H‐indole (50 μL, 0.40 mmol, 1.0 eq). Full conversion of the indole was reached overnight. Purification by flash column chromatography on silica gel using petroleum ether (100 %) as eluent afforded the title compound 2e (109 mg, 0.41 mmol, 100 %) as a colorless oil that crystallized upon storage cold. ¹H NMR (300 MHz, CDCl₃): δ/ppm = 7.70 (dt, J = 7.9, 1.0 Hz, 1H), 7.62 – 7.55 (m, 2H), 7.45 – 7.38 (m, 3H), 7.38 – 7.32 (m, 1H), 7.33 – 7.23 (m, 1H), 7.15 (ddd, J = 7.9, 6.8, 1.1 Hz, 1H), 6.86 (d, J = 1.0 Hz, 1H), 3.69 (s, 3H), 0.71 (s, 6H).¹³C{¹H} NMR (75 MHz, CDCl3): δ/ppm = 140.5, 139.0, 137.7, 134.2, 129.6, 128.5, 128.2, 122.3, 120.9, 119.3, 113.2, 109.2, 33.1, - 1.7. ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl3): δ/ppm = 0.71/–14.7. The spectroscopic data match the literature report.¹⁶ 1-Phenyl-2-(triethylsilyl)-1H-indole (3b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 eq.) and 1-phenyl-1H-indole (97 mg, 0.50 mmol, 1.0 eq). Full conversion of the indole was reached within 1 h. Purification by flash column chromatography on silica gel using petroleum ether (100 %) as eluent afforded the title compound 3b (140 mg, 0.46 mmol, 91 %) as a white solid. Rf = 0.41 petroleum ether:ethyl acetate (99:1). ¹H NMR (400 MHz, CDCl3): δ/ppm = 7.69 – 7.66 (m, 1H), 7.53 – 7.46 (m, 3H), 7.40 – 7.35 (m, 2H), 7.16 – 7.05 (m, 3H), 6.90 (s, 1H), 1.05-0.80 (m, 9H), 0.62 – 0.51 (m, 6H).¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 141.5, 140.6, 139.1, 129.3, 128.7, 128.6, 128.4, 122.4, 120.5, 119.8, 114.8, 110.4, 7.5, 3.9.¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 6.9, 0.92, 0.57/‐1.7. The spectroscopic data match the literature report.⁷ 1-cyclopentyl-2-(triethylsilyl)-1H-indole (4b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 eq.) and 1-cyclopentyl-1H-indole (59 mg, 0.50 mmol, 1.0 eq). Full conversion of the indole was reached within 1 h. Purification by flash column chromatography on silica gel using petroleum ether/ethyl acetate (99:1) as eluent afforded the title compound 4b (104 mg, 0.35 mmol, 69 %) as a yellow oil. R_f = 0.40 petroleum ether/ethyl acetate (99:1).¹H NMR (300 MHz, CDCl₃): δ/ppm = 7.63 (d, J = 7.8 Hz, 1H), 7.44 (d, J = 8.2 Hz, 1H), 7.15 (t, J = 7.6 Hz, 1H), 7.07 (ddd, J = 7.9, 7.0, 1.0 Hz, 1H), 6.65 (s, 1H), 4.80 (p, J = 9.0 Hz, 1H), 2.39 (ddd, J = 13.7, 10.4, 6.3 Hz, 2H), 2.19 – 1.96 (m, J = 5.1, 4.1 Hz, 4H), 1.90 – 1.70 (m, 2H), 1.07 – 0.97 (m, 9H), 0.96 – 0.84 (m, 6H).¹³C{¹H} NMR (75 MHz, CDCl₃): δ/ppm = 139.2, 136.9, 130.5, 121.3, 121.24, 118.9, 112.5, 111.8, 61.4, 30.3, 25.5, 7.7, 4.2. ¹H/²⁹Si-HMQC NMR (300/60 MHz, CDCl₃): δ/ppm = 6.66/- 2.9 HRMS (APCI) m/z: [M+H]⁺ Calcd for C₁₉H₂₉NSiH: 300.2142; Found: 300.2142. tert-butyl 2-(trimethylsilyl)-1H-indole-1-carboxylate (5a) Prepared according to GP4 from the corresponding diazene 1a (119 mg, 0.75 mmol, 1.5 eq.), 1-Boc-indole (109 mg, 0.50 mmol, 1.0 eq) and potassium tert-butoxide (tBuOK, 20 mol%, 11.2 mg, 0.2 eq). Full conversion of the indole was reached overnight (18 h). Purification by flash column chromatography on silica gel using petroleum ether:ethyl acetate (9:1) as eluent afforded the title compound 5a (110 mg, 0.38 mmol, 76 %) as an off-white solid. R_f = 0.40 petroleum ether/ethyl acetate (99/1). ¹H NMR (400 MHz, CDCl₃): δ/ppm = 7.99 (dq, J = 8.3, 0.9 Hz, 1H), 7.54 (ddd, J = 7.6, 1.5, 0.8 Hz, 1H), 7.28 (ddd, J = 8.4, 7.2, 1.4 Hz, 1H), 7.19 (td, J = 7.5, 1.1 Hz, 1H), 6.84 (d, J = 0.9 Hz, 1H), 1.72 (s, 9H), 0.36 (s, 9H).¹³C{¹H} NMR (75 MHz, CDCl3): δ/ppm = 151.4, 142.4, 137.8, 131.2, 124.4, 122.5, 120.9, 119.3, 115.6, 83.9, 28.4, 0.2.¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 0.36/–9.8. HRMS (APCI) m/z: [M+H]⁺ Calcd for C₁₆H₂₃NO₂SiH: 290.1571; Found: 290.1572. 4-methoxy-1-methyl-2-(triethylsilyl)-1H-indole (6b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 eq.) and 4-methoxy-1-methyl-indole (81 mg, 0.50 mmol, 1.0 eq). Full conversion of the indole was reached after 2 h. Purification by flash column chromatography on silica gel using petroleum ether:ethyl acetate (98:2) as eluent afforded the title compound 6b (128 mg, 0.465 mmol, 93%) as a yellow oil. R_f = 0.42 petroleum ether:ethyl acetate (98:2). ¹H NMR (400 MHz, CDCl₃): δ/ppm = 7.15 (t, J = 8.1 Hz 1H), 6.96 (d, J = 8.2 Hz, 1H), 6.82 (s, 1H), 6.49 (d, J = 7.7 Hz, 1H), 3.97 (s, 3H), 3.82 (s, 3H), 1.02 – 0.95 (m, 9H), 0.95 – 0.84 (m, 6H).¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 153.2, 142.0, 136.8, 122.9, 119.3, 110.1, 102.7, 98.9, 55.4, 33.4, 7.7, 4.1. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 1.0/‐2.6. HRMS (ESI) m/z: [M+H]⁺ Calculated for C16H26NOSi: 276.1778; Found: 276.1780. 5-methoxy-1-methyl-2-(triethylsilyl)-1H-indole (7b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 eq.) and 5-methoxy-1-methylindole (81 mg, 0.50 mmol, 1.0 eq). Full conversion of the indole was reached after 2 h. Purification by flash column chromatography on silica gel using petroleum ether:ethyl acetate (99:1) as eluent afforded the title compound 7b (125 mg, 0.455 mmol, 91%) as a white solid. Rf = 0.39 petroleum ether:ethyl acetate (98:2). ¹H NMR (400 MHz, CDCl3): δ/ppm = 7.21 (d, J = 8.9 Hz 1H), 7.07 (d, J = 2.4 Hz, 1H), 6.89 (dd, J = 8.9, 2.5 Hz, 1H), 6.63 (s, 1H), 3.85 (s, 3H), 3.80 (s, 3H), 1.02 – 0.98 (m, 9H), 0.92 – 0.88 (m, 6H). ¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 154.0, 139.0, 135.9, 128.9, 112.6, 112.3, 109.8, 102.1, 56.1, 33.3, 7.7, 4.1.¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 1.0/‐2.6. The spectroscopic data match the literature report.⁷ 6-methoxy-1-methyl-2-(triethylsilyl)-1H-indole (8b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 eq.) and 6-methoxy-1-methyl-1H-indole (81 mg, 0.50 mmol, 1.0 eq) Full conversion of the indole was reached after 2 h. Purification by flash column chromatography on silica gel using petroleum ether:ethyl acetate (98:2) as eluent afforded the title compound 8b (143 mg, 0.519 mmol, >99%) as a white solid. Rf = 0.45 petroleum ether:ethyl acetate (98:2). M.p. (CH2Cl2) : 48.6 °C. ¹H NMR (400 MHz, CDCl3): δ/ppm = 7.47 (d, J = 9.2 Hz 1H), 6.77 (s, 1H), 6.76 (overlapped, 1H), 6.65 (s, 1H), 3.89 (s, 3H), 3.78 (s, 3H), 1.02 – 0.98 (m, 9H), 0.92 – 0.88 (m, 6H). ¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 156.8, 141.1, 137.1, 123.1, 121.2, 113.1, 109.4, 92.6, 55.9, 33.1, 7.7, 4.2. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 1.0/‐3.0. HRMS (ESI) m/z: [M+H]⁺ Calculated for C16H25NOSiH 276.1778. Found 276.1780. 1,4-dimethyl-2-(triethylsilyl)-1H-indole (9b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 eq.) and 1,4-dimethylindole (73 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 2 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 9b (134 mg, 0.52 mmol, > 99%; 90% pure according to ¹H NMR) as a colorless oil. R_f = 0.56 petroleum ether:ethyl acetate (98:2). ¹H NMR (400 MHz, CDCl₃): δ/ppm = 7.21 – 7.09 (m, 2H), 6.89 (d, J = 6.5 Hz, 1H), 6.73 (s, 1H), 3.84 (s, 3H), 2.58 (s, 3H), 1.05 – 0.97 (m, 9H), 0.96 – 0.89 (m, 6H). ¹³C{¹H} NMR (101 MHz, CDCl3): δ/ppm = 140.1, 137.4, 130. 2, 122.1, 119.3, 111.5, 106.8, 33.2, 18.8, 7.7, 4.2. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 6.73, 1.0/‐2.6. The spectroscopic data match the literature report.⁷ 1,5-dimethyl-2-(triethylsilyl)-1H-indole (10b) Prepared according to GP4 from the corresponding diazene 1b (100 mg, 0.50 mmol, 1.0 eq.) and 1,5-dimethylindole (73 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 2 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 10b (91 mg, 0.35 mmol, 70%) as a colorless oil. R_f = 0.40 petroleum ether:ethyl acetate (98:2). ¹H NMR (400 MHz, CDCl₃): δ/ppm 7.39 (s, 1H), 7.21 (d, J = 8.4 Hz, 1H), 7.05 (d, J = 8.4 Hz, 1H), 6.63 (s, 1H), 3.81 (s, 3H), 2.45 (s, 3H), 1.03 – 0.98 (m, 9H), 0.93 – 0.87 (m, 6H). ¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 138.8, 138.4, 128.9, 128.3, 123.6, 120.2, 112.4, 108.8, 33.1, 21.5, 7.7, 4.2. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 6.67, 1.0/‐2.6. The spectroscopic data match the literature report.⁷ 1,7-dimethyl-2-(triethylsilyl)-1H-indole (11b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 eq.) and 1,7-dimethylindole (73 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 2 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 11b (100 mg, 0.39 mmol, 77%, 92% pure according to ¹H NMR) as a colorless oil. Rf = 0.60 petroleum ether:ethyl acetate (98:2). ¹H NMR (400 MHz, CDCl3): δ/ppm = 7.43 (d, J = 7.5 Hz, 1H), 6.94 – 6.87 (m, 2H), 6.66 (s, 1H), 4.11 (s, 3H), 2.80 (s, 3H), 1.03 – 0.98 (m, 9H), 0.92 – 0.84 (m, 6H).¹³C{¹H} NMR (101 MHz, CDCl3): δ/ppm = 139.3, 139.1, 129.8, 125.1, 121.1, 119.4, 119.0, 113.6, 36.8, 20.6, 7.7, 4.2. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 6.66, 1.0/‐2.6. The spectroscopic data match the literature report.⁷ 1,3-dimethyl-2-(triethylsilyl)-1H-indole (12b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 eq.) and 1,3-dimethylindole (73 mg, 0.50 mmol, 1.0 eq.). The reaction mixture was stirred for 2 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 12b (93 mg, 0.36 mmol, 72%) as a colorless oil. Rf (PE) = 0.36.¹H NMR (400 MHz, CDCl3): δ/ppm 7.57 (d, J = 7.9 Hz, 1H), 7.28 (d, J = 8.2 Hz, 1H), 7.25 – 7.15 (m, 1H), 7.08 (t, J = 7.4 Hz, 1H), 3.81 (s, 3H), 2.43 (s, 2H), 1.06 – 0.86 (m, 15H). ¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 140.0, 133.4, 129.4, 122.1, 121.8, 118.7, 118.4, 108.9, 33.1, 10.9, 7.7, 5.0. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 1.01/-1.0. 1-methyl-5-phenyl-2-(triethylsilyl)-1H-indole (13b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.50 mmol, 1.2 eq.) and 5-phenyl-1-methylindole (66 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 30 min at room temperature. Purification by column chromatography on silica gel using pentane/CH₂Cl₂ (8:2) as eluent afforded the title compound 13b (154 mg, 0.48 mmol, 96%) as a white solid. R_f = 0.26 petroleum ether:ethyl acetate (98:2). ¹H NMR (400 MHz, CDCl₃): δ/ppm = 7.82 (s, 1H), 7.65 (d, J = 7.5 Hz, 2H), 7.52 – 7.35 (m, 4H), 7.30 (t, J = 7.2 Hz, 1H), 6.77 (s, 1H), 3.87 (s, 3H), 1.05-1.00 (m, 9H), 0.96-0.89 (m, 6H).¹³C{¹H} NMR (101 MHz, CDCl3): δ/ppm = 142.9, 139.9, 139.4, 132.8, 129.1, 128.7, 127.5, 126.3, 122.0, 119.2, 113.4, 109.4, 33.2, 7.7, 4.1. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 6.77, 1.0/‐2.55. The spectroscopic data match the literature report.⁷ 5-chloro-1-methyl-2-(triethylsilyl)-1H-indole (14b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 eq.), 5-chloro-1-methylindole (83 mg, 0.50 mmol, 1.0 eq) and potassium tert-butoxide (11.2 mg, 0.10 mmol, 20 mol%). The reaction mixture was stirred for 16 h at room temperature. Purification by column chromatography on silica gel using petroleum ether (100 %) as eluent afforded the title compound 14b (106 mg, 0.379 mmol, 76%) as a colorless oil. Rf = 0.54 petroleum ether:ethyl acetate (98:2). ¹H NMR (400 MHz, CDCl3): δ/ppm = 7.56 (d, J = 1.9 Hz, 1H), 7.22 (d, J = 8.7 Hz, 1H), 7.15 (dd, J = 8.7, 1.6 Hz, 1H), 6.64 (s, 1H), 3.81 (s, 3H), 1.02 – 0.94 (m, 9H), 0.94 – 0.87 (m, 6H). ¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm= 140.3, 138.8, 129.6, 125.0, 122.2, 119.9, 112.4, 110.1, 77.6, 77.2, 76.7, 33.3, 7.6, 4.1. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 6.64, 1.0/‐2.7. HRMS (APCI) m/z: [M+H]⁺ Calcd. for C15H23ClNSi 280.1283; Found 280.1284. 5-fluoro-1-methyl-2-(triethylsilyl)-1H-indole (15b) Prepared according to GP4 from the corresponding diazene 1b (100 mg, 0.50 mmol, 1.0 eq.) and 5-fluoro-1-methylindole (75 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 2 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 15b (91 mg, 0.35 mmol, 69%) as a colorless oil. R_f = 0.50 petroleum ether:ethyl acetate (98:2).¹H NMR (400 MHz, CDCl₃): δ/ppm = 7.23 (m, 2H), 6.96 (td, J = 9.1, 2.5 Hz, 1H), 6.65 (s, 1H), 3.82 (s, 3H), 1.03 – 0.95 (m, 9H), 0.95 – 0.87 (m, 6H). ¹³C{¹H} NMR (101 MHz, CDCl3): δ/ppm = 157.8 (d, J = 234 Hz),, 140.5, 137.1, 128.8 (d, JCF = 9.9 Hz), 112.7 (d, JCF = 4.8 Hz), 110.3 (d, JCF = 26.6 Hz), 109.6 (d, JCF = 9.8 Hz), 105.1 (d, J_CF = 23.0 Hz), 33.4, 7.6, 4.1. ¹⁹F{¹H} NMR (376 MHz, CDCl₃): δ/ppm = ‐126.4. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 1.0/‐2.4. HRMS (APCI) m/z: [M+H]⁺ Calcd. for C₁₅H₂₃FNSi 264.1578; Found 264.1579. 1-methyl-2-(trimethylsilyl)-1H-indole-5-carboxylate (16a) Prepared according to GP4 from the corresponding diazene 1a (198 mg, 1.25 mmol, 2.5 eq.), sodium tert-butoxide (9.6 mg, 0.10 mmol, 20 mol%) and 1-methylindole-5- carboxylate (95 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 2 h at room temperature. Purification by column chromatography on silica gel using petroleum ether/ethyl acetate (95:5) as eluent afforded the title compound 16a (76 mg, 0.29 mmol, 58%) as a white solid. R_f = 0.21 petroleum ether:ethyl acetate (95:5). M.p. (CH₂Cl₂): 115.3 °C. ¹H NMR (300 MHz, CDCl₃): δ/ppm = 8.36 (d, J = 1.6, 0.7 Hz, 1H), 7.92 (dd, J = 8.7, 1.7 Hz, 1H), 7.31 (d, J = 8.7 Hz, 1H), 6.77 (s, 1H), 3.93 (s, 3H), 3.77 (s, 3H), 0.42-0.38 (m, 9H). ¹³C{¹H} NMR (101 MHz, CDCl3): δ/ppm = 168.4, 143.3, 142.6, 128.0, 123.9, 123.5, 121.3, 113.1, 108.8, 51.9, 33.3, ‐ 0.46.¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 0.4/‐10.4. HRMS (APCI) m/z: [M+H]⁺ Calcd for C14H19NO2SiH 262.1258; Found 262.1259. 1-methyl-2-(triethylsilyl)indole-4-carbonitrile (17a) Prepared according to GP4 from the corresponding diazene 1a (198 mg, 1.25 mmol, 2.5 eq.), potassium tert-butoxide (11.2 mg, 0.10 mmol, 20 mol%) and 1-methylindole-4-carbonitrile (78.1 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 1 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 17a (68 mg, 0.30 mmol, 59%) as a yellow oil. R_f = 0.55 petroleum ether:ethyl acetate (9:1). ¹H NMR (400 MHz, CDCl₃): δ/ppm = 7.53 (dt, J = 8.3, 0.9 Hz, 1H), 7.43 (dd, J = 7.3, 0.9 Hz, 1H), 7.23 (dd, J = 8.3, 7.3 Hz, 1H), 6.87 (d, J = 1.0 Hz, 1H), 3.89 (s, 3H), 0.43 (s, 9H).¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 145.1, 139.9, 129.5, 124.7, 121.5, 119.0, 113.8, 110.1, 102.8, 33.3, -0.6.¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 0.43/‐9.8. HRMS (ESI) m/z: [M+H]⁺ Calcd for C13H16N2SiH 229.11586; Found: 262.1160. 1-methyl-2-(triethylsilyl)-1H-pyrrolo[2,3-b]pyridine (18b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.50 mmol, 1.2 eq.) and 1-methylpyrrolo[2,3-b]pyridine (66 mg, 0.50 mmol, 1.0 eq.). The reaction mixture was stirred for 2 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 18b (108 mg, 0.44 mmol, 88%) as a yellow oil. Rf = 0.23 petroleum ether:ethyl acetate (95:5). ¹H NMR (400 MHz, CDCl3): δ 8.34 (dd, J = 4.7, 1.5 Hz, 1H), 7.87 (dd, J = 7.8, 1.5 Hz, 1H), 7.01 (dd, J = 7.8, 4.6 Hz, 1H), 6.67 (s, 1H), 3.95 (s, 3H), 1.06 – 0.97 (m, 9H), 0.97 – 0.83 (m, 6H).¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 150.9, 143.2, 139.2, 128.4, 120.6, 115.3, 111.0, 31.4, 7.6, 3.9.¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 6.67, 1.0/‐1.7. The spectroscopic data match the literature report.⁷ Benzofuran-2-yltriethylsilane (19b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 eq.) and benzofuran (59 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 1 h at room temperature. Purification by column chromatography on silica gel using petroleum ether/ethyl acetate (98:2) as eluent afforded the title compound 19b (104 mg, 0.42 mmol, 90%) as a colorless oil. R_f = 0.76 petroleum ether:ethyl acetate (98:2).¹H NMR (400 MHz, CDCl₃): δ/ppm = 7.58 (d, J = 7.7 Hz, 1H), 7.51 (d, J = 8.1 Hz, 1H), 7.27 (m, 1H), 7.20 (t, J = 7.4 Hz, 1H), 6.99 (s, 1H), 1.06-0.95 (m, 9H), 0.61-0.50 (m, 6H). ¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 161.8, 158.3, 128.1, 124.3, 122.3, 121.0, 117.3, 111.4, 7.5, 3.3. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 6.99, 1.0, 0.58/‐1.85. The spectroscopic data match the literature report.¹⁷ Benzo[b]thiophen-2-yltriethylsilane (20b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 eq.) and benzothiophene (67 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 1 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 20b (78 mg, 0.31 mmol, 63%) as a yellow oil. R_f = 0.76 petroleum ether ¹H NMR (400 MHz, CDCl₃): δ/ppm = 7.90 (d, J = 8.0 Hz, 1H), 7.83 (d, J = 7.6, 2.0 Hz, 1H), 7.48 (s, 1H), 7.38−7.28 (m, 2H), 1.05 (t, 9H), 0.96‐0.83 (m, 6H). ¹³C{¹H} NMR (101 MHz, CDCl3): δ/ppm = 143.7, 141.2, 139.1, 131.7, 124.2, 124.0, 123.5, 122.3, 7.5, 4.4. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 7.48, 0.97/1.16. The spectroscopic data match the literature report.¹³ 2,5-bis(triethylsilyl)furan (21b₂) Prepared according to GP4 from the corresponding diazene 1b (441 mg, 2.2 mmol, 2.2 eq.), potassium tert-butoxide (11.2 mg, 0.10 mmol, 10 mol%) and furan (68 mg, 1.0 mmol, 1.0 eq). The reaction mixture was stirred for 30 min at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 21b₂ (271 mg, 0.916 mmol, 92%) as a colorless oil. R_f = 0.77 petroleum ether. ¹H NMR (400 MHz, CDCl₃): δ/ppm = 6.62 (s, 2H), 1.01–0.91 (m, 18H), 0.79–0.73 (m, 12H). ¹³C{¹H} NMR (101 MHz, CDCl3): δ/ppm = 162.8, 120.0, 7.4, 3.6. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 6.62, 1.0, 0.74/‐4.0. The spectroscopic data match the literature report.¹⁷ 2,5-Bis(triethylsilyl)thiophene (22b₂) Prepared according to GP4 from the corresponding diazene 1b (301 mg, 1.5 mmol, 3.0 eq.), potassium tert-butoxide (11.2 mg, 0.10 mmol, 20 mol%) and thiophene (42 mg, 0.5 mmol, 1.0 eq). The reaction mixture was stirred for 30 min at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 22b2 (154 mg, 0.498 mmol, > 99%,) as a colorless oil. Rf = 0.71 petroleum ether. ¹H NMR (400 MHz, CDCl3): δ/ppm = 7.32 (s, 2H), 1.07–0.88 (m, 18H), 0.85–0.77 (m, 12H). ¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 142.4, 135.6, 7.6, 4.8. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 7.32, 1.0/‐0.43. The spectroscopic data match the literature report.¹⁷ Triethyl(5-pentylfuran-2-yl)silane (23b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.50 mmol, 1.2 eq.) and 5-pentylfuran (69 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 1 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 23b (127 mg, 0.503 mmol, > 99%) as a colorless liquid. R_f = 0.86 petroleum ether.¹H NMR (400 MHz, CDCl₃): δ/ppm = 6.53 (d, J = 3.0 Hz, 1H), 5.96 (d, J = 3.0 Hz, 1H), 2.64 (t, J = 7.6 Hz, 2H), 1.64 (p, J = 7.3 Hz, 2H), 1.36 – 1.31 (m, 4H), 0.98 (t, J = 7.9 Hz, 9H), 0.95-85 (m, 3H), 0.74 (q, J = 7.9 Hz, 6H). ¹³C{1H} NMR (101 MHz, CDCl3): δ/ppm = 161.2, 156.2, 121.5, 104.6, 31.6, 28.3, 27.9, 22.6, 14.2, 7.5, 3.5. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 0.98, 0.74/‐4.2. The spectroscopic data match the literature report.⁷ (2-fluoro-3-trimethylsilylphenyl)-trimethylsilane (24a₂) Prepared according to GP4 from the corresponding diazene 1a (198 mg, 1.25 mmol, 2.5 eq.), potassium tert‐butoxide (10 mol%, 5.6 mg, 0.1 eq) and fluorobenzene (47 μL, 0.5 mmol, 1.0 eq). The reaction mixture was stirred for 1 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 24a2 (112 mg, 0.47 mmol, 93%) as a colorless liquid. Caution: product is slightly volatile and should be dried under high vacuum with care. Rf (petroleum ether) = 0.67. ¹H NMR (300 MHz, CDCl3): δ/ppm = 7.43 (dd, J = 7.1, 5.9 Hz, 1H), 7.13 (td, J = 7.2, 1.6 Hz, 1H), 0.33 (d, J = 1.0 Hz, 9H).¹³C{¹H} NMR (101 MHz, CDCl3): δ/ppm = 172.2 (d, J = 236.6 Hz), 136.8 (d, J = 11.8 Hz), 125.3 (d, J = 35.4 Hz), 123.7 (d, J = 2.8 Hz), –0.8 (d, J = 1.8 Hz). ¹⁹F{¹H} NMR (282 MHz, CDCl₃) δ/ppm = ‐86.8. ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl₃): δ/ppm = 0.33/-4.5. Tert-butyl(2-fluorophenyl)dimethylsilane (24c) Prepared according to GP4 from the corresponding diazene 1c (120 mg, 0.6 mmol, 1.2 eq.), potassium tert‐butoxide (10 mol%, 5.6 mg, 0.1 eq) and fluorobenzene (47 μL, 0.5 mmol, 1.0 eq). The reaction mixture was stirred for 1 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 24c (67 mg, 0.32 mmol, 64%) as a colorless liquid. Caution: product is volatile and should be dried under high vacuum with care. ¹H NMR (300 MHz, CDCl₃): δ/ppm = 7.45 – 7.28 (m, 2H), 7.12 (tt, J = 7.2, 1.0 Hz, 1H), 7.05 – 6.93 (m, 1H), 0.90 (d, J = 0.8 Hz, 9H), 0.32 (d, J = 1.4 Hz, 6H). ¹³C{¹H} NMR (101 MHz, CDCl3): δ/ppm = 167.5 (d, J = 241.5 Hz), 136.5 (d, J = 11.5 Hz), 131.3 (d, J = 8.4 Hz), 123.8 (d, J = 30.8 Hz), 123.7 (d, J = 2.9 Hz), 115.0 (d, J = 26.6 Hz), 26.7 (d, J = 1.4 Hz), 17.3, –5.1 (d, J = 2.9 Hz).¹⁹F{¹H} NMR (282 MHz, CDCl3) δ/ppm = ‐97.0. ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl₃): δ/ppm = 0.90, 0.32/–3.9. The spectroscopic data match the literature report.¹⁸ (2-fluoro-6-methoxy-1,3-phenylene)bis(trimethylsilane) (25a₂) Prepared according to GP4 from the corresponding diazene 1a (277 mg, 1.75 mmol, 3.5 eq.), potassium tert-butoxide (10 mol%, 5.6 mg, 0.1 eq) and 1-fluoro-3-methoxybenzene (63 mg, 0.5 mmol, 1.0 eq). The reaction mixture was stirred for 15 h at room temperature. Purification by column chromatography on silica gel using petroleum ether/dichloromethane (98:2) as eluent afforded the title compound 25a2 (137 mg, 0.51 mmol, > 99%) as a white solid. R_f (PE/CH₂Cl₂ 98:2) = 0.73. M.p.: 63 °C (CH₂Cl₂). ¹H NMR (300 MHz, CDCl₃): δ/ppm = 7.34 (dd, J = 8.1, 6.8 Hz, 1H), 6.62 (d, J = 8.1 Hz, 1H), 3.79 (s, 3H), 0.31 (d, J = 1.9 Hz, 9H), 0.27 (d, J = 1.0 Hz, 9H). ¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 172.3 (d, J = 237.5 Hz), 167.1 (d, J = 16.3 Hz), 137.5 (d, J = 14.8 Hz), 117.4 (d, J = 37.7 Hz), 113.0 (d, J = 36.8 Hz), 105.8 (d, J = 2.6 Hz), 55.5, 0.9 (d, J = 3.7 Hz), -0.7 (d, J = 1.7 Hz). ¹⁹F{¹H} NMR (282 MHz, CDCl3) δ/ppm = –84.5. ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl3): δ/ppm = 0.29/–5.3. HRMS (APCI) m/z: [M]⁺ Calcd. for C₁₃H₂₃FOSi₂: 270.1266; Found: 270.1267. (2-fluoro-5-methoxy-1,3-phenylene)bis(triethylsilane) (26b₂) Prepared according to GP4 from the corresponding diazene 1b (301 mg, 1.5 mmol, 3.0 eq.), potassium tert-butoxide (10 mol%, 5.6 mg, 0.1 eq) and 1-fluoro-4-methoxybenzene (63 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 15 h at room temperature. Purification by column chromatography on silica gel using petroleum ether/dichloromethane (99:1) as eluent afforded the title compound 26b2 (165 mg, 0.46 mmol, 93%) as a pale-yellow oil. Rf (PE/CH2Cl299:1) = 0.25.¹H NMR (300 MHz, CDCl3): δ/ppm = 6.88 (d, J = 4.1 Hz, 2H), 3.79 (s, 3H), 1.03 – 0.89 (m, 18H), 0.89 – 0.76 (m, 12H). ¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 166.6 (d, J = 228.9 Hz), 155.2 (d, J = 2.0 Hz), 123.4 (d, J = 39.7 Hz), 121.8 (d, J = 12.8 Hz), 55.8, 7.5, 3.6 (d, J = 1.9 Hz).¹⁹F{¹H} NMR (282 MHz, CDCl₃) δ/ppm = ‐96.8. ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl3): δ/ppm = 0.94/3.3. HRMS (APCI) m/z: [M]⁺ Calcd. for C19H35FOSi2: 354.2205; Found: 354.2206. Triethyl(2-fluoro-3-methoxyphenyl)silane (27b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 eq.), potassium tert-butoxide (10 mol%, 5.6 mg, 0.1 eq) and 1-fluoro-2-methoxybenzene (63 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 1 h at room temperature. Purification by column chromatography on silica gel using petroleum ether/dichloromethane (98:2) as eluent afforded the title compound 27b (96 mg, 0.40 mmol, 80%) as a colorless liquid. Rf (PE/CH2Cl2 98:2) = 0.13. ¹H NMR (300 MHz, CDCl3): δ/ppm = 7.11 – 7.03 (m, 1H), 7.01 – 6.87 (m, 2H), 3.88 (s, 3H), 1.02 – 0.91 (m, 9H), 0.91 – 0.76 (m, 6H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ/ppm = 156.7 (d, J = 239.2 Hz), 147.3 (d, J = 14.5 Hz), 126.8 (d, J = 11.5 Hz),124.3 (d, J = 29.3 Hz), 124.2 (d, J = 3.4 Hz), 114.4 (d, J = 2.1 Hz), 56.2, 7.5, 3.6 (d, J = 1.6 Hz). ¹⁹F{¹H} NMR (282 MHz, CDCl₃) δ/ppm = –122.6. ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl₃): δ/ppm = 0.95/3.3. HRMS (APCI) m/z: [M]⁺ Calcd. for C13H21FOSi: 240.1340; Found 240.1341. (2-fluoro-4-((trimethylsilyl)oxy)phenyl)trimethylsilane (28a) Prepared according to GP4 from the corresponding diazene 1a (218 mg, 1.38 mmol, 2.8 eq.), potassium tert‐butoxide (20 mol%, 11.2 mg, 0.10 mmol) and 3‐fluorophenol (51 μL, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 19 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 28a (81 mg, 0.32 mmol, 63%) as a colorless liquid. Rf (PE) = 0.76. ¹H NMR (300 MHz, CDCl3): δ/ppm = 7.17 (td, J = 8.2, 7.0 Hz, 1H), 6.63 – 6.51 (m, 2H), 0.33 (s, 9H), 0.32 (d, J = 1.9 Hz, 9H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ/ppm = 168.1 (d, J = 241.6 Hz), 161.4 (d, J = 15.6 Hz), 131.3 (d, J = 11.2 Hz), 116.3 (d, J = 30.5 Hz), 113.0 (d, J = 3.0 Hz), 108.1 (d, J = 27.7 Hz), 0.8 (d, J = 3.8 Hz, 3C), 0.7 (3C). ¹⁹F{¹H} NMR (282 MHz, CDCl3) δ/ppm ‐97.7. ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl3): δ/ppm = 0.33/18.4, 0.32/-5.5. HRMS (APCI) m/z: [M]⁺ Calcd. for C12H21FOSi2H: 257.1188; Found: 257.1189. (2-fluoro-5-phenoxy-1,3-phenylene)bis(triethylsilane) (29b₂) Prepared according to GP4 from the corresponding diazene 1b (251 mg, 1.25 mmol, 2.5 eq.), potassium tert-butoxide (5.6 mg, 0.05 mmol, 10 mol%) and 1-fluoro-4- phenoxybenzene (82 μL, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 15 h at room temperature. Purification by column chromatography on silica gel using hexane as eluent afforded the title compound 29b2 (142 mg, 0.34 mmol, 68%) as a colorless liquid. Rf (Hexane) = 0.79. ¹H NMR (300 MHz, CDCl3): δ/ppm = 7.38 – 7.24 (m, 2H), 7.10 – 7.01 (m, 3H), 6.99 – 6.92 (m, 2H), 1.01 – 0.90 (m, 18H), 0.88 – 0.75 (m, 12H).¹³C{¹H} NMR (75 MHz, CDCl₃): δ/ppm = 168.2 (d, J = 232.4 Hz), 158.5, 152.0 (d, J = 2.4 Hz), 129.8 (2C), 128.1 (d, J = 13.3 Hz, 2C), 124.3 (d, J = 40.2 Hz, 2C), 122.6 (1C), 117.5 (2C), 7.5 (6C), 3.6 (d, J = 1.8 Hz, 6C).¹⁹F{¹H} NMR (282 MHz, CDCl₃) δ/ppm = –92.4. ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl3): δ/ppm = 7.03/3.3. HRMS (APCI) m/z: [M]⁺ Calcd. for C24H37FOSi2: 416.2361; Found: 416.2363. (5-chloro-2-fluorophenyl)triethylsilane (30b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.6 eq.), potassium tert-butoxide (11.2 mg, 0.10 mmol, 20 mol%) and 1-chloro-4-fluorobenzene (65 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 18 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 30b (83 mg, 0.34 mmol, 68%) as a colorless liquid. R_f (PE) = 0.95. ¹H NMR (300 MHz, CDCl₃): δ/ppm = 7.35 – 7.23 (m, 2H), 7.00 – 6.87 (m, 1H), 1.04 – 0.87 (m, 9H), 0.93 – 0.75 (m, 6H).¹³C{¹H} NMR (75 MHz, CDCl₃): δ/ppm = 165.9 (d, J = 240.6 Hz), 135.5 (d, J = 12.6 Hz), 131.0 (d, J = 9.0 Hz), 129.3 (d, J = 3.1 Hz), 126.1 (d, J = 33.9 Hz), 116.4 (d, J = 28.8 Hz), 7.4, 3.4 (d, J = 1.6 Hz).¹⁹F{¹H} NMR (282 MHz, CDCl₃) δ/ppm = -103.1. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 0.95/3.7. (2-fluoro-5-methyl-1,3-phenylene)bis(trimethylsilane) (31a2) Prepared according to GP4 from the corresponding diazene 1a (277 mg, 1.75 mmol, 2.5 eq.), potassium tert-butoxide (10 mol%, 7.9 mg, 0.1 eq) and 1-fluoro-4-methylbenzene (77 mg, 0.7 mmol, 1.0 eq). The reaction mixture was stirred for 1 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 31a2 (123 mg, 0.48 mmol, 69%) as a white solid. Rf (PE) = 0.85. M.p.: 47 °C (CH2Cl2). ¹H NMR (300 MHz, CDCl3): δ/ppm = 6.88 (d, J = 4.1 Hz, 2H), 3.79 (s, 3H), 1.03 – 0.89 (m, 18H), 0.89 – 0.76 (m, 12H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ/ppm = 170.56 (d, J = 234.1 Hz), 137.13 (d, J = 11.7 Hz), 132.51 (d, J = 3.0 Hz), 124.99 (d, J = 35.5 Hz), 20.82 (d, J = 1.5 Hz), -0.76 (d, J = 1.8 Hz).¹⁹F{¹H} NMR (282 MHz, CDCl₃) δ/ppm = -92.9.¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl3): δ/ppm = 0.29/‐4.7. HRMS (APCI) m/z: [M]⁺ Calcd. for C13H23FSi2: 254.1317; Found: 254.1317. Triethyl(2-fluoro-[1,1'-biphenyl]-3-yl)silane (32b) Prepared according to GP4 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 eq.), potassium tert-butoxide (10 mol%, 5.6 mg, 0.05 mmol) and 2-fluoro-1,1'-biphenyl (86 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 1 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 32b (141 mg, 0.49 mmol, 99%) as a yellow liquid. R_f (PE) = 0.72. ¹H NMR (400 MHz, CDCl₃): δ/ppm = 7.55 (dq, J = 6.3, 1.5 Hz, 2H), 7.45 (tt, J = 7.8, 1.4 Hz, 3H), 7.40 – 7.32 (m, 2H), 7.21 (t, J = 7.4 Hz, 1H), 1.05 – 0.95 (m, 9H), 0.98 – 0.82 (m, 6H). ¹³C{¹H} NMR (101 MHz, CDCl3): δ/ppm = 164.2 (d, J = 242.2 Hz), 136.5, 135.4 (d, J = 12.4 Hz), 132.2 (d, J = 3.8 Hz), 129.3 (d, J = 2.9 Hz), 128.5 (d, J = 18.0 Hz), 128.5, 127.6, 124.2 (d, J = 3.3 Hz), 124.2 (d, J = 34.0 Hz), 7.6, 3.7 (d, J = 1.7 Hz). ¹⁹F{¹H} NMR (376 MHz, CDCl3) δ/ppm = ‐104.5.¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 1.0/3.5, 7.4/3.5. HRMS (APCI) m/z: [M]⁺ Calcd. for C18H23FSi: 286.1548; Found: 286.1547. Trimethyl(2-phenoxyphenyl)silane (33a) Prepared according to GP4 from the corresponding diazene 1a (95 mg, 0.60 mmol, 1.2 eq.), potassium tert-butoxide (5.6 mg, 0.05 mmol, 10 mol%) and diphenylether (85 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 1 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 33a (70 mg, 0.29 mmol, 58%) as a colorless liquid. ¹H NMR (400 MHz, CDCl₃): δ/ppm = 7.54 – 7.47 (m, 1H), 7.38 – 7.24 (m, 3H), 7.10 (q, J = 7.4 Hz, 2H), 6.98 (d, J = 8.0 Hz, 2H), 6.81 (d, J = 8.2 Hz, 1H), 0.29 (s, 9H). ¹³C{¹H} NMR (101 MHz, CDCl3): δ/ppm = 162.1, 157.7, 135.5, 130.8, 130.8, 129.8, 123.11, 123.05, 118.9, 117.6, -0.77.¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 0.29/‐4.9. The spectroscopic data match the reported ones.¹⁹ Triethyl(2-fluoro-3-methoxy-4-(trimethylsilyl)phenyl)silane (34a) Prepared according to GP4 from the corresponding diazene 1a (95 mg, 0.60 mmol, 1.2 eq.), potassium tert-butoxide (10 mol%, 5.6 mg, 0.05 mmol) and triethyl(2-fluoro-3- methoxyphenyl)silane (27b) (120 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 2 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 34a (73 mg, 0.23 mmol, 47%) as a colorless liquid. R_f (PE) = 0.58.¹H NMR (300 MHz, CDCl₃): δ/ppm = 7.11 (d, J = 7.3 Hz, 1H), 7.04 (dd, J = 7.1, 3.9 Hz, 1H), 3.92 (d, J = 2.3 Hz, 3H), 1.04 – 0.93 (m, 9H), 0.91 – 0.79 (m, 6H), 0.30 (s, 9H). ¹³C{¹H} NMR (101 MHz, CDCl3): δ/ppm = 159.3 (d, J = 243.8 Hz), 151.4 (d, J = 12.0 Hz), 136.0, 129.73 (d, J = 10.4 Hz), 129.55 (d, J = 3.0 Hz), 126.9 (d, J = 30.3 Hz, 1C), 61.0 (d, J = 7.9 Hz), 7.55 (3C), 3.72 (d, J = 1.7 Hz, 3C), -0.6 (3C).¹⁹F{¹H} NMR (282 MHz, CDCl3) δ/ppm = -118.2. ¹H/²⁹Si HMQC NMR (300/60 MHz, CDCl3): δ/ppm = 7.11/-5.1, 7.03/3.3, 0.95/3.3, 0.31/-5.01. HRMS (APCI) m/z: [M]⁺ Calcd. for C₁₆H₂₉FOSi₂: 312.1735; Found 312.1736. 3-Fluoro-2-(trimethylsilyl)phenyl diisopropylcarbamate (35a) Prepared according to GP4 from the corresponding diazene 1a (238 mg, 1.50 mmol, 3.0 eq.), sodium tert-butoxide (12.0 mg, 0.15 mmol, 30 mol%) and 3-fluorophenyl diisopropylcarbamate (120 mg, 0.50 mmol, 1.0 eq). The reaction mixture was stirred for 1 h at room temperature. Purification by column chromatography on silica gel using petroleum ether/ethyl acetate (99:1 → 98:2) as eluent afforded the title compound 35a (75 mg, 0.24 mmol, 48%) as a white crystalline solid. R_f (PE/AcOEt 9:1) = 0.69. M.p.: 78–80 °C (CH₂Cl₂) ¹H NMR (400 MHz, CD₂Cl₂): δ/ppm = 7.32 (td, J = 8.2, 6.8 Hz, 1H), 6.85 (t, J = 8.6 Hz, 1H), 6.76 (d, J = 8.1 Hz, 1H), 4.28 (dq, J = 13.6, 6.8 Hz, 1H), 3.75 (hept, J = 6.7 Hz, 1H), 1.32 (d, J = 6.8 Hz, 6H), 1.29 (d, J = 6.8 Hz, 6H), 0.33 (d, J = 1.8 Hz, 9H).¹³C{¹H} NMR (101 MHz, CD2Cl2): δ/ppm = 167.7 (d, J = 241.7 Hz), 157.5 (d, J = 14.8 Hz), 153.4, 131.3 (d, J = 10.6 Hz), 120.0 (d, J = 31.5 Hz), 119.0 (d, J = 3.3 Hz), 112.0 (d, J = 27.1 Hz), 47.7, 46.5, 21.4, 20.6, 0.5 (d, J = 3.5 Hz). ¹⁹F{¹H} NMR (376 MHz, CD₂Cl₂): δ/ppm = ‐98.4. ¹H/²⁹Si-HMQC NMR (400/79 MHz, CD₂Cl₂): δ/ppm = 0.33/‐4.9. HRMS (APCI) m/z: [M+H]⁺ Calcd. for C₁₆H₂₆FNO₂SiH: 312.1790; Found: 312.1791. 1-Methyl-2,5-bis(triethylsilyl)pyrrole (36b₂) Prepared according to GP3 from the corresponding diazene 1b (1.0 mmol, 2.0 equiv) and N- methylpyrrole (40.6 mg, 0.50 mmol, 1 equiv). The reaction mixture was stirred for 1 h at room temperature. Purification by column chromatography on silica gel using petroleum ether:ethyl acetate (98:2) as eluent afforded the title compound (134 mg, 0.686 mmol, 87%, 88% pure according to ¹H NMR (traces of mono species) as a colorless oil. Note: ca. 12 % of the title compound underwent protodesilylation during purification. R_f = 0.53 petroleum ether:ethyl acetate (98:2). ¹H NMR (400 MHz, CDCl₃): δ/ppm = 6.41 (s, 2H), 3.75 (s, 3H), 0.99–0.91 (m, 18H), 0.84–0.78 (m, 12H). ¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm =135.5, 120.2, 37.6, 7.8, 4.4.¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 6.41, 0.90/-4.8. HRMS (APCI) m/z: [M+H]⁺ Calcd for C17H36NSi2310.2381; Found 310.2381. 1-Methyl-2-(triethylsilyl)-4-((triethylsilyl)methyl)-1H-indole (37b2) Prepared according to GP3 from the corresponding diazene 1b (351 mg, 1.75 mmol, 3.5 equiv.), potassium tert-butoxide (20 mol%, 11.2 mg, 0.2 equiv) and 1,4-dimethylindole (73 mg, 0.5 mmol, 1.0 equiv). The reaction mixture was stirred for 2 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 37b2 (153 mg, 0.41 mmol, 82%) as a colorless oil. Rf = 0.36 petroleum ether:ethyl acetate (98:2). ¹H NMR (400 MHz, CDCl3): δ/ppm = 7.10‐ 7.03 (m, 2H), 6.72 (d, J = 6.7 Hz, 1H) 6.67 (s, 1H) 3.8 (s, 3H), 2.38 (s, 2H), 1.0 (t, J = 7.2 Hz, 9H), 0.93-0.87 (m, 15H), 0.52 (q, J = 7.9 Hz, 6H).¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 140.3, 136.5, 133.2, 128.1, 122.1, 118.2, 112.3, 105.0, 33.2, 18.8, 7.6, 4.2, 3.6. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 6.73, 1.0/‐2.6; 2.38, 1.0, 0.9/7.1. HRMS (ESI) m/z: [M+H]⁺ Calculated for C22H39NSi2H 374.2694. Found 374.2693. 1-Methyl-2-(triethylsilyl)-7-((triethylsilyl)methyl)-1H-indole (38b2) Prepared according to GP3 from the corresponding diazene 1b (351 mg, 1.75 mmol, 3.5 equiv.), potassium tert-butoxide (20 mol%, 11.2 mg, 0.2 equiv) and 1,7-dimethylindole (73 mg, 0.5 mmol, 1.0 equiv). The reaction mixture was stirred for 2 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 38b2 (116 mg, 0.310 mmol, 62%) as a colorless oil. Rf = 0.7 petroleum ether:ethyl acetate (98:2). ¹H NMR (300 MHz, CDCl3): δ/ppm = δ 7.32 (d, J = 7.5 Hz, 1H), 6.90 (t, J = 7.5 Hz, 1H), 6.77 (d, J = 7.5 Hz, 1H), 6.65 (s, 1H), 4.07 (s, 3H), 2.62 (s, 2H), 1.03 – 0.99 (m, 9H), 0.97 – 0.83 (m, 15H), 0.59 – 0.50 (m, 6H).¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 139.5, 138.5, 130.3, 123.9, 119.5, 117.1, 113.8, 37.5, 18.2, 7.7, 4.3, 3.6. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 1.0/‐2.6; 2.62, 0.87/6.5. HRMS (ESI) m/z: [M+H]⁺ Calculated for C22H39NSi2H 374.2694. Found 374.2693. 1-Methyl-2-(triethylsilyl)-5-((triethylsilyl)methyl)-1H-indole (39b2) Prepared according to GP3 from the corresponding diazene 1b (351 mg, 1.75 mmol, 3.5 equiv.), potassium tert-butoxide (20 mol%, 11.2 mg, 0.2 equiv) and 1,7-dimethylindole (73 mg, 0.5 mmol, 1.0 equiv). The reaction mixture was stirred for 2 h at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 39b2 (123 mg, 0.33 mmol, 66%) as a colorless oil. Rf = 0.55 petroleum ether:ethyl acetate (98:2). ¹H NMR (400 MHz, CDCl3): δ/ppm = 7.22 (s, 1H), 7.16 (d, J = 8.4 Hz, 1H), 6.90 (d, J = 8.4 Hz, 1H), 6.60 (s, 1H), 3.79 (s, 3H), 2.17 (s, 2H), 1.03 – 0.87 (m, 24H), 0.57 – 0.51 (m, 6H). ¹³C{¹H} NMR (101 MHz, CDCl₃): δ/ppm = 138.2, 130.7, 129.1, 123.4, 119.1, 112.2, 108.6, 33.1, 21.0, 7.7, 4.2, 3.2. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl3): δ/ppm = 6.60, 1.0/‐2.9; 2.17, 1.0, 0.58/6.25. HRMS (ESI) m/z: [M+H]⁺ Calculated for C22H39NSi2H 374.2694. Found 374.2688. (E)-1-(3-(triethylsilyl)prop-1-en-1-yl)-1H-indole (40b) A 10-mL vial equipped with a magnetic stirring bar was charged with KOtBu (10 mol%, 5.6 mg), THF (2.0 mL) and 1-allyl-1H-indole (79 mg, 0.50 mmol, 1.0 equiv). To the resulting stirred mixture was then added dropwise a solution of diazene 1b (120 mg, 0.60 mmol, 1.2 equiv) in THF (1.0 mL). The reaction mixture was stirred for 2 h at room temperature. Purification by flash column chromatography on silica gel using petroleum ether as eluent afforded the title compound 40b (91 mg, 0.33 mmol, 67 %) as a colorless oil (E/Z ratio = 89:11). R_f = 0.30 (petroleum ether). ¹H NMR (300 MHz, CDCl₃): δ/ppm = 7.62 (d, J = 7.8 Hz, 1H), 7.43 (d, J = 7.8 Hz, 1H), 7.30 (d, J = 3.2 Hz, 1H), 7.27 – 7.17 (m, 1H), 7.14 (d, J = 6.8 Hz, 1H), 6.85 (d, J = 13.9 Hz, 1H), 6.57 (d, J = 3.4 Hz, 1H), 5.79 (dt, J = 13.9, 8.4 Hz, 1H), 1.67 (dd, J = 8.4, 1.4 Hz, 2H), 1.00 (t, J = 7.9 Hz, 9H), 0.62 (q, J = 7.9 Hz, 6H). ¹³C{¹H} NMR (75 MHz, CDCl3) δ/ppm = 135.3, 128.7, 124.8, 122.4, 122.1, 121.0, 120.1, 114.8, 109.6, 103.1, 14.8, 7.40, 3.2. HRMS (ESI) m/z: [M+H]⁺ Calcd. for C₁₇H₂₅NSiH: 272.1829; Found: 272.1835. (E)-5-methyl-1-(3-(triethylsilyl)prop-1-en-1-yl)-1H-indole (41b) A 10-mL vial equipped with a magnetic stirring bar was charged with KOtBu (10 mol%, 5.6 mg), THF (2.0 mL) and 1-allyl-5-methyl-1H-indole (85 mg, 0.50 mmol, 1.0 equiv). To the resulting stirred mixture was then added dropwise a solution of diazene 1b (120 mg, 0.50 mmol, 1.2 equiv) in THF (1.0 mL). The reaction mixture was stirred for 16 h at room temperature. Purification by flash column chromatography on silica gel using petroleum ether as eluent afforded the title compound 41b (107 mg, 0.38 mmol, 75 %) as a colorless oil (E/Z ratio = 87:13) Rf = 0.50 (petroleum ether). ¹H NMR (300 MHz, CDCl3): inter alia δ/ppm = 7.39 (s, 1H), 7.31 (d, J = 8.4 Hz, 1H), 7.25 (s, 1H), 7.06 (dd, J = 8.3, 1.6 Hz, 1H), 6.82 (d, J = 13.8 Hz, 1H), 6.47 (d, J = 3.4 Hz, 1H), 5.75 (dt, J = 13.8, 8.4 Hz, 1H), 2.45 (s, 3H), 1.66 (dd, J = 8.5, 1.4 Hz, 2H), 0.99 (t, J = 7.9 Hz, 9H), 0.67 – 0.46 (m, 6H). ¹³C{¹H} NMR (75 MHz, CDCl₃): δ/ppm = 133.8, 129.4, 129.1, 124.9, 123.8, 122.8, 120.8, 114.2, 109.4, 102.8, 21.5, 14.9, 7.5, 3.3. HRMS (ESI) m/z: [M+H]⁺ Calcd. for C₁₈H₂₇NSiH: 286.1986; Found: 286.199. (E)-5-methoxy-1-(3-(triethylsilyl)prop-1-en-1-yl)-1H-indole (42b) A 10-mL vial equipped with a magnetic stirring bar was charged with KOtBu (10 mol%, 5.6 mg), THF (2.0 mL) and 1-allyl-5-methoxy-1H-indole (94 mg, 0.50 mmol, 1.0 equiv). To the resulting stirred mixture was then added dropwise a solution of diazene 1b (120 mg, 0.60 mmol, 1.2 equiv) in THF (1.0 mL). The reaction mixture was stirred for 16 h at room temperature. Purification by flash column chromatography on silica gel using petroleum ether/ethyl acetate = 100/1 as eluent afforded the title compound 42b (111 mg, 0.37 mmol, 74 %) as a yellow oil (E/Z ratio = 91:9). R_f = 0.22 (petroleum ether/ethyl acetate = 100/1). ¹H NMR (300 MHz, CDCl₃, major isomer): δ/ppm = 7.31 (d, J = 8.9 Hz, 1H), 7.08 (d, J = 2.5 Hz, 1H), 6.89 (dd, J = 8.9, 2.5 Hz, 1H), 6.79 (d, J = 13.9 Hz, 1H), 6.48 (d, J = 3.3 Hz, 1H), 5.75 (dt, J = 13.8, 8.4 Hz, 1H), 3.85 (s, 3H), 1.65 (dd, J = 8.4, 1.4 Hz, 2H), 0.99 (t, J = 7.9 Hz, 9H), 0.68 – 0.46 (m, 6H). ¹³C{¹H} NMR (75 MHz, CDCl3, major isomer): δ/ppm = 154.5, 130.7, 129.2, 125.3, 122.7, 114.4, 112.3, 110.4, 102.9, 102.9, 56.1, 14.9, 7.5, 3.3. HRMS (ESI) m/z: [M+H]⁺ Calcd for: C₁₈H₂₇NOSiH 302.1935; Found: 302.1941. 5-bromo-1-(3-(triethylsilyl)prop-1-en-1-yl)-1H-indole (43b) A 10-mL vial equipped with a magnetic stirring bar was charged with KOtBu (10 mol%, 5.6 mg), THF (2.0 mL) and 1-allyl-5-bromo-1H-indole (118 mg, 0.50 mmol, 1.0 equiv). To the resulting stirred mixture was then added dropwise a solution of (E)-1-(tert-butyl)-2- (triethylsilyl) diazene (120 mg, 0.60 mmol, 1.2 equiv) in THF (1.0 mL). The reaction mixture was stirred for 16 h at room temperature. Purification by flash column chromatography on silica gel using petroleum ether as eluent afforded the title compound 43b (69 mg, 0.20 mmol, 40 %) as a colorless oil (E/Z ratio = 78:22). Rf = 0.40 (petroleum ether). ¹H NMR (300 MHz, CDCl3, major diastereoisomer): δ/ppm inter alia = 6.75 (d, J = 14.0 Hz, 1H), 6.47 (d, J = 3.3 Hz, 1H), 5.78 (dt, J = 13.8, 8.5 Hz, 1H), 1.64 (d, J = 8.4 Hz, 2H), 0.98 (t, J = 7.9 Hz, 9H), 0.59 (q, J = 7.9 Hz, 6H).¹³C{¹H} NMR (75 MHz, CDCl_3, both diastereoisomers): δ/ppm = 135.0, 134.1, 130.4, 129.9, 128.9, 126.1, 125.0, 124.8, 123.6, 123.3, 122.2, 121.6, 116.3, 113.4, 111.9, 111.1, 102.7, 102.1, 15.0, 13.2, 7.5, 7.3, 3.32, 3.25. HRMS (APCI) m/z: [M]⁺ Calcd. for: C17H24BrNSi 349.0856; Found: 349.0858. (E)-5-methoxy-1-(3-(triethylsilyl)prop-1-en-1-yl)-1H-indole (44b) A 10-mL vial equipped with a magnetic stirring bar was charged with KOtBu (10 mol%, 5.6 mg), THF (2 mL) and 1-allyl-4-methoxy-1H-indole (93.6 mg, 0.5 mmol, 1 eq.). To the resulting stirred mixture was then added dropwise a solution of diazene 1b (120.2 mg, 0.6 mmol, 1.2 equiv) in THF (1.0 mL). The reaction mixture was stirred for 16 h at room temperature. Purification by flash column chromatography on silica gel using (petroleum ether/DCM = 10/1) as eluent afforded the title compound 44b (93.8 mg, 0.20 mmol, 62%) as a colorless oil (E/Z ratio = 91:9). R_f = 0.6 (petroleum ether/DCM = 10/1). ¹H NMR (300 MHz, CDCl₃): δ/ppm = 7.23 – 7.08 (m, 2H), 7.04 (d, J = 8.2 Hz, 1H), 6.81 (d, J = 13.9 Hz, 1H), 6.66 (d, J = 3.3 Hz, 1H), 6.55 (d, J = 7.7 Hz, 1H), 5.77 (dt, J = 13.8, 8.4 Hz, 1H), 3.96 (s, 3H), 1.65 (dd, J = 8.4, 1.3 Hz, 2H), 0.99 (t, J = 7.9 Hz, 9H), 0.61 (q, J = 7.9 Hz, 6H). ¹³C{1H} NMR (75 MHz, CDCl3): δ/ppm = 153.5, 136.9, 123.4, 123.1, 122.8, 119.2, 115.1, 103.2, 100.5, 100.2, 55.5, 14.9, 7.5, 3.3. HRMS (APCI) m/z: [M+H]⁺ Calcd. for C₁₈H₂₇NOSiH: 302.1935; Found 302.1936. Triethyl(4-methoxybenzyl)silane (45b) Prepared according to GP4 from the corresponding diazene 1b (301 mg, 1.50 mmol, 1.5 equiv.), potassium tert-butoxide (5.6 mg, 10 mol%), 4-methylanisole (61 mg, 0.50 mmol, 1.0 equiv) and THF (0.5 mL, 1 M). The reaction mixture was stirred for ca. 18 h at room temperature. Purification by column chromatography on silica gel using petroleum ether/ethyl acetate (99:1) as eluent afforded the title compound 45b (83 mg, 0.351 mmol, 70%) as a colorless liquid. Rf = 0.36 petroleum ether:ethyl acetate (99:1). ¹H NMR (400 MHz, CDCl3): δ/ppm = 6.93 (d, J＝ 8.3 Hz, 2H), 6.77 (d, J＝8.4 Hz, 2H), 3.77 (s, 3H), 2.03 (s, 2H), 0.94-0.87 (m, 9H), 0.59- 0.47 (m, 6H). ¹³C{1H} NMR (101 MHz, CDCl₃): δ/ppm = 156.6, 132.6, 129.0, 113.8, 55.4, 20.4, 7.5, 3.1. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 2.03, 0.92, 0.49/6.3. The spectroscopic data match the literature report (Chin. J. Org. Chem., 2015, 35, 1375-1379.). Triethyl(hept-1-yn-1-yl)silane (46b) Prepared according to GP3 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 equiv.), potassium tert-butoxide (5.6 mg, 10 mol%) and hept-1-yne (48 mg, 0.50 mmol, 1.0 equiv). The reaction mixture was stirred for 30 min at room temperature. Purification by column chromatography on silica gel using petroleum ether as eluent afforded the title compound 46b (105 mg, 0.500 mmol, > 99%) as a colorless liquid. Rf = 0.69 petroleum ether. ¹H NMR (400 MHz, CDCl3): δ/ppm = 2.23 (t, J = 7.1 Hz, 2H), 1.52 (q, J = 7.3 Hz, 2H), 1.45 – 1.24 (m, 4H), 0.98 (t, J = 7.9 Hz, 9H), 0.91 (m, 3H), 0.57 (q, J = 7.9 Hz, 6H). ¹³C{1H} NMR (101 MHz, CDCl₃): δ/ppm = 109.0, 81.5, 31.1, 28.6, 22.3, 20.0, 14.1, 7.6, 4.8. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 2.23, 0.98, 0.57/‐8.6. The spectroscopic data match the literature report (J. Am. Chem. Soc.2020, 142, 13867–13877). Triethyl(phenylethynyl)silane (47b) Prepared according to GP3 from the corresponding diazene 1b (120 mg, 0.60 mmol, 1.2 equiv.), potassium tert-butoxide (5.6 mg, 10 mol%) and ethynylbenzene (51 mg, 0.50 mmol, 1.0 equiv). The reaction mixture was stirred for 30 min at room temperature. Purification by column chromatography on silica gel using petroleum ether/ethyl acetate (99:1) as eluent afforded the title compound 47b (104 mg, 0.48 mmol, 94%) as a colorless liquid. R_f = 0.62 petroleum ether:ethyl acetate (99:1). ¹H NMR (400 MHz, CDCl₃): δ/ppm = 7.50‐ 7.46 (m, 2H), 7.34-7.28 (m, 3H), 1.05 (t, J = 7.9 Hz, 9H), 0.64 (q, J = 7.9 Hz, 6H); ¹³C{1H} NMR (101 MHz, CDCl₃): δ/ppm = 132.2, 128.5, 128.3, 123.5, 106.5, 91.7, 7.7, 4.6. ¹H/²⁹Si HMQC NMR (400/79 MHz, CDCl₃): δ/ppm = 1.05, 0.64/‐7.2. The spectroscopic data match the literature report (Adv. Synth. Catal., 2009, 351, 2055-2062). 4. Regioselectivity 1-methyl-5-fluoroindole undergoes regioselective silylation alpha to the nitrogen atom with 1 equivalent of diazene tBuN₂SiEt₃ (60 % yield, entry 1 in table 1), while silylation occurs alpha to the nitrogen and at the two positions ortho to the fluorine atom with 5 equivalents of diazene tBuN₂SiEt₃ (62 % yield for tri-silylated product 15b₃, entry 4). 5. References (1) (a) Cheng, C.; Hartwig, J. F. Catalytic Silylation of Unactivated C-H Bonds. Chem. Rev. 2015, 115, 8946–8975. (b) Richter, S. C.; Oestreich, M. Emerging Strategies for C–H Silylation. Trends Chem. 2020, 2, 13–27. (2) Williams, N. A.; Uchimaru, Y.; Tanaka, M. Platinum catalysed regioselective ortho- silylation of benzylideneamines via intramolecular C–H activation. J. Chem. Soc., Chem. Commun. 1995, 1129–1130. (3) Cheng, C.; Hartwig, J. F. Rhodium-catalyzed intermolecular C-H silylation of arenes with high steric regiocontrol. Science 2014, 343, 853–857. (4) Tyagi, A.; Yadav, N.; Khan, J.; Singh, S.; Kumar Hazra, C. Transition‐Metal‐Free C−H Silylation: An Emerging Strategy. Asian J. Org. Chem. 2021, 10, 334–354. (5) (a) Curless, L. D.; Clark, E. R.; Dunsford, J. J.; Ingleson, M. J. E-H (E = R3Si or H) bond activation by B(C6F5)3 and heteroarenes; competitive dehydrosilylation, hydrosilylation and hydrogenation. Chem. Commun. 2014, 50, 5270–5272. (b) Ma, Y.; Wang, B.; Zhang, L.; Hou, Z. Boron-Catalyzed Aromatic C-H Bond Silylation with Hydrosilanes. J. Am. Chem. Soc.2016, 138, 3663–3666. (6) (a) Dai, C.; Zhan, Y.; Liu, P.; Sun, P. Organic photoredox catalyzed C–H silylation of quinoxalinones or electron-deficient heteroarenes under ambient air conditions. Green Chem. 2021, 23, 314–319. (b) Liu, S.; Pan, P.; Fan, H.; Li, H.; Wang, W.; Zhang, Y. Photocatalytic C-H silylation of heteroarenes by using trialkylhydrosilanes. Chem. Sci.2019, 10, 3817–3825. (c) Rammal, F.; Di Gao; Boujnah, S.; Hussein, A. A.; Lalevée, J.; Gaumont, A.-C.; Morlet-Savary, F.; Lakhdar, S. Photochemical C–H Silylation and Hydroxymethylation of Pyridines and Related Structures: Synthetic Scope and Mechanisms. ACS Catal. 2020, 10, 13710–13717. (7) Toutov, A. A.; Liu, W.-B.; Betz, K. N.; Fedorov, A.; Stoltz, B. M.; Grubbs, R. H. Silylation of C-H bonds in aromatic heterocycles by an Earth-abundant metal catalyst. Nature 2015, 518, 80–84. (8) Zhao, L.; Shi, X.; Cheng, J. Calcium-Catalyzed Dehydrogenative Silylation of Aromatic Ethers with Hydrosilane. ACS Catal. 2021, 11, 2041–2046. (9) Tobisu, M.; Ano, Y.; Chatani, N. Rhodium-catalyzed silylation of aromatic carbon- hydrogen bonds in 2-arylpyridines with disilane. Chem. Asian J.2008, 3, 1585–1591. (10) Kakiuchi, F.; Matsumoto, M.; Sonoda, M.; Fukuyama, T.; Chatani, N.; Murai, S.; Furukawa, N.; Seki, Y. A New Synthetic Route to Heteroarylsilanes via Ruthenium-Catalyzed C-H/SiR₃ Coupling. Chem. Lett. 2000, 29, 750–751. (11) (a) Ishiyama, T.; Sato, K.; Nishio, Y.; Miyaura, N. Direct synthesis of aryl halosilanes through iridium(I)-catalyzed aromatic C-H silylation by disilanes. Angew. Chem. Int. Ed. 2003, 42, 5346–5348. (b) Ishiyama, T.; Sato, K.; Nishio, Y.; Saiki, T.; Miyaura, N. Regioselective aromatic C-H silylation of five-membered heteroarenes with fluorodisilanes catalyzed by iridium(I) complexes. Chem. Commun. 2005, 5065–5067. (c) Kanyiva, K. S.; Kuninobu, Y.; Kanai, M. Palladium-catalyzed direct C-H silylation and germanylation of benzamides and carboxamides. Org. Lett.2014, 16, 1968–1971. (d) Sakakura, T.; Tokunaga, Y.; Sodeyama, T.; Tanaka, M. Catalytic C–H Activation. Silylation of Arenes with Hydrosilane or Disilane by RhCl(CO)(PMe₃)₂ under Irradiation. Chem. Lett. 1987, 16, 2375–2378. (12) Sasaki, M.; Kondo, Y. Deprotonative C-H silylation of functionalized arenes and heteroarenes using trifluoromethyltrialkylsilane with fluoride. Org. Lett.2015, 17, 848–851. (13) Nozawa-Kumada, K.; Osawa, S.; Sasaki, M.; Chataigner, I.; Shigeno, M.; Kondo, Y. Deprotonative Silylation of Aromatic C-H Bonds Mediated by a Combination of Trifluoromethyltrialkylsilane and Fluoride. J. Org. Chem. 2017, 82, 9487–9496. (14) García-Domínguez, A.; Helou de Oliveira, P. H.; Thomas, G. T.; Sugranyes, A. R.; Lloyd- Jones, G. C. Mechanism of Anion-Catalyzed C–H Silylation Using TMSCF3: Kinetically- Controlled CF3-Anionoid Partitioning As a Key Parameter. ACS Catal. 2021, 11, 3017–3025. (15) Zhou, S.; Wang, J.; Wang, L.; Chen, K.; Song, C.; Zhu, J. Co(III)-Catalyzed, Internal and Terminal Alkyne-Compatible Synthesis of Indoles. Org. Lett. 2016, 18, 3806–3809. (16) Ma, Y.; Zhang, L.; Luo, Y.; Nishiura, M.; Hou, Z. B(C6F5)3-Catalyzed C-Si/Si-H Cross- Metathesis of Hydrosilanes. J. Am. Chem. Soc. 2017, 139, 12434–12437. (17) Fang, H.; Le Guo; Zhang, Y.; Yao, W.; Huang, Z. A Pincer Ruthenium Complex for Regioselective C-H Silylation of Heteroarenes. Org. Lett.2016, 18, 5624–5627. (18) Yoshinaga, T.; Fujiwara, T.; Iwata, T.; Shindo, M. Synthesis of Distorted 1,8,13-Trisilyl- 9-hydroxytriptycenes by Triple Cycloaddition of Ynolates to 3-Silylbenzynes. Chem. Eur. J. 2019, 25, 13855–13859. (19) Corrie, T. J. A.; Ball, L. T.; Russell, C. A.; Lloyd-Jones, G. C. Au-Catalyzed Biaryl Coupling To Generate 5- to 9-Membered Rings: Turnover-Limiting Reductive Elimination versus π‐Complexation. J. Am. Chem. Soc. 2017, 139, 245–254.

Claims

CLAIMS 1. A method for silylating an organic substrate comprising at least one silylatable C-H bond, said method comprising the step of reacting said organic substrate with a mixture comprising : (a) a silylated diazene of formula (I) wherein R is selected in the group consisting of C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, aryl, heteroaryl, heterocycloalkyl, C3-C7 cycloalkyl, Si(C1-C6alkyl)3 and Si(O-C1-C6 alkyl)3, said alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocycloalkyl and cycloalkyl being optionally substituted, and R¹, R² and R³ are each independently selected in the group consisting of H, C₁-C₁₂ alkyl, C₂- C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₁-C₁₂ alcoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocycloalkyl, C₃-C₇ cycloalkyl, halogen and siloxy, said alkyl, alkenyl, alkynyl, alcoxy, aryl, aryloxy heteroaryl, heteroaryloxy, siloxy, heterocycloalkyl and cycloalkyl being optionally substituted, and (b) a catalyst. 2. The method according to claim 1, characterized in that the organic substrate is selected in the group consisting of optionally substituted arene, optionally substituted heteroarene, optionally substituted alkane, optionally substituted alkene and optionally substituted alkyne. 3. The method according to claim 1 or 2, characterized in that the organic substrate responds to one of the following formulae: wherein • X is N–R’, O or S, • R’ is selected in the group consisting of C₁-C₁₂ alkyl, C₁-C₁₂ haloalkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, -C(O)O-C₁-C₁₂ alkyl, aryl, heteroaryl, heterocycloalkyl and cycloalkyl, said alkyl, haloalkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl or heterocycloalkyl being optionally substituted, • R⁵, R⁶, R⁷ and R⁸ are independently selected in the group consisting of H, halogen, aryl, heteroaryl, N3, OH, CN, NO2 and a C1-C12 aliphatic chain wherein one or more, preferably 1 to 4, methylene unit(s) is eventually replaced by -O-, -C(O)-, -N-, NR’’-, -S-, -S(O)-, -P-, -B- or -Si-, said aliphatic chain, aryl or heteroaryl being optionally substituted, or R⁵ and R⁶ or R⁶ and R⁷ or R⁷ and R⁸, together with the atoms to which they are bonded, form a fused aryl, heteroaryl, cycloalkyl or heterocycloalkyl, said aryl, heteroaryl, cycloalkyl and heterocycloalkyl being optionally substituted, • R⁹, R¹⁰, R¹¹, R¹², R¹³ and R¹⁴ are independently selected in the group consisting of H, halogen, aryl, heteroaryl, N₃, OH, CN, NO₂ and a C₁-C₁₂ aliphatic chain wherein one or more, preferably 1 to 4, methylene unit(s) is eventually replaced by -O-, -C(O)-, -N-, NR’’-, -S-, - S(O)-, -P-, -B- or -Si-, said aliphatic chain, aryl or heteroaryl being optionally substituted, or two or more of R⁹, R¹⁰, R¹¹, R¹², R¹³ and R¹⁴, together with the atoms to which they are bonded, form an aryl, a heteroaryl, a cycloalkyl or a heterocycloalkyl, said aryl, heteroaryl, cycloalkyl and heterocycloalkyl being optionally substituted, • R¹⁵ and R¹⁶ are independently selected in the group consisting of H, C₁-C₁₂ alkyl, C₁-C₁₂ haloalkyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, heteroaryl, heterocycloalkyl and cycloalkyl, said alkyl, haloalkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl or heterocycloalkyl being optionally substituted, • R¹⁷ and R¹⁸ are independently selected in the group consisting of H, halogen, N3, oxo, OH, CN, NO2 and a C1-C12 aliphatic chain wherein one or more, preferably 1 to 4, methylene unit(s) is eventually replaced by -O-, -C(O)-, -N-, NR’’’-, -S-, -S(O)-, -P-, -B- or -Si-, said aliphatic chain being optionally substituted, or R¹⁷ and R¹⁸, together with the atom to which they are bonded, form a a cycloalkyl or a heterocycloalkyl, said cycloalkyl and heterocycloalkyl being optionally substituted, • R¹⁹ and R²⁰ are independently selected in the group consisting of H, halogen and a C1-C12 aliphatic chain wherein one or more, preferably 1 to 4, methylene unit(s) is eventually replaced by -O-, -C(O)-, -N-, NR’’’-, -S-, -S(O)-, -P-, -B- or -Si-, said aliphatic chain, being optionally substituted, and ^ R’’ is H, C1-C12 alkyl, C1-C12 haloalkyl, C2-C12 alkenyl, aryl or heteroaryl, said alkyl, haloalkyl, alkenyl, aryl or heteroaryl being optionally substituted, and ^ R’’’ is H, C1-C12 alkyl, C1-C12 haloalkyl, C2-C12 alkenyl or heteroaryl, said alkyl, haloalkyl, alkenyl or heteroaryl being optionally substituted. 4. The method according to any one of claims 1 to 3, characterized in that the organic substrate is of formula (II). 5. The method according to any one of claims 1 to 4, characterized in that in the diazene of formula (I), R is a C₁-C₆ alkyl, preferably a tert-butyl. 6. The method according to any one of claims 1 to 5, characterized in that, in the diazene of formula (I), R¹, R² and R³ are each independently selected in the group consisting of H, C₁- C6 alkyl and aryl. 7. The method according to any one of claims 1 to 6, characterized in that the diazene of formula (I) is selected in the group consisting of the following compounds: 8. The method according to any one of claims 1 to 7, characterized in that the catalyst is a salt of an ammonium, a phosphonium, an alkali metal, an alkaline earth metal or mixture thereof, preferably selected in the group consisting of ^tBuOLi, ^tBuOK, ^tBuONa, Me3SiOK, KOH, CsF or mixture thereof. 9. The method according to any one of claims 1 to 8, characterized in that the mixture comprises one or more additives, preferably selected in the group consisting of crown ethers such as 18-crown-6, cryptands, polyamino compounds such as N,N,N’,N’- tetramethylenediamine (TMEDA) and nitrogen heterocycles such as pyridine, bipyridine or phenantroline. 10. The method according to any one of claims 1 to 9, characterized in that the mixture is substantially free of a transition-metal. 11. The method according to any one of claims 1 to 10, further comprising the steps of (i) preparing the silylated diazene of formula (I) as defined in any of claims 1 and 5 to 7 by oxidation of the corresponding hydrazine, (ii) reacting the organic substrate as defined in any one of claims 1 to 4, with a mixture comprising said silylated diazene of formula (I) and the catalyst as defined in any one of claims 1 and 8. 12. The method according to claim 11, characterized in that step (ii) comprises the following sub-steps: (ii-1) charging a reactor with a reaction medium comprising the organic substrate comprising at least one silylatable C-H bond, and a solvent, (ii-2) adding the catalyst to the reaction medium, (ii-3) adding the diazene of formula (I)to the reaction medium, (iii-4) recovering the silylated compound. 13. A composition comprising: (a’) a silylated compound, (b’) at least one impurity resulting from the reaction of an organic substrate comprising at least one silylatable C-H bond with a mixture comprising: - a silylated diazene of formula (I) as defined in any one of claims 1 and 5 to 7, and - a catalyst, preferably as defined in claim 8. 14. The composition according to claim 13, wherein the at least one impurity is selected among the following compounds: in which R, R¹, R² and R³ are as defined in any one of claims 1 and 5 to 7. 15. The composition according to claim 13 or 14, wherein the at least one impurity is in traces amount.