EP2142556A1 - Preparation and use of magnesium amides - Google Patents

Abstract

The present application relates to mixed Mg/Li amides of the general formula R1R2N-Mg-NR3R4.zLiY (II) wherein R1, R2, R3, and R4 are, independently, selected from H, substituted or unsubstituted aryl or heteroaryl containing one or more heteroatoms, linear, branched or cyclic, substituted or unsubstituted alkyl, alkenyl, alkynyl, or silyl derivatives thereof; and R1 and R2 together, or R3 and R4 together can be part of a cyclic or polymeric structure; and wherein at least one of R1 and R2 and at least one of R3 and R4 is other than H; Y is selected from the group consisting of F; Cl; Br; I; CN; SCN; NCO; HaIOn, wherein n = 3 or 4 and Hal is selected from Ci, Br and I; NO3; BF4; PF6; H; a carboxylate of the general formula RxCO2; an alcoholate of the general formula ORx; a thiolate of the general formula SRx; RxP(O)O2; or SCORx; or SCSRx; OnSRx, wherein n = 2 or 3; or NOn, wherein n = 2 or 3; and a derivative thereof; wherein Rx is a substituted or unsubstituted aryl or heteroaryl containing one or more heteroatoms, linear, branched or cyclic, substituted or unsubstituted alkyl, alkenyl, alkynyl, or derivatives thereof, or H; m is O or 1; and z > 1; as well as a process for the preparation of the mixed Mg/Li amides and the use of these amides, e.g. as bases.

Description

Preparation and use of magnesium amides

The present application relates to magnesium amides, a method for the preparation of magnesium amides and the use of these amides.

The metalation of aromatics is one of the most useful transformations in organic synthesis since it allows the regioselective functionalization of various aryl derivatives. ^tl] Traditionally, strong bases such as alkyl lithium (RLi) or lithium amides (R₂NLi) have been used to perform such deprotonations. However, these highly reactive bases display often undesirable side reactions due to the too high reactivity of the resulting aryl lithium compounds. Another serious limitation is the low stability of lithium amides in THF solutions at room temperature which requires an in situ generation of these reagents. Furthermore, the deprotonation of aromatics by lithium bases often requires very low temperatures (-78 °C to -90⁰C) which complicates the scale-up of these reactions and the use of solvent mixtures such as THF/pentane may be needed.

Alternative methods have been developed using magnesium amides'²-¹ such as compounds 1-3 or amido zincates^[3] 4 (see Scheme 1). The low solubility of the magnesium amides R₂NMgCl (1) could be improved by Eaton who developed the use of magnesium amides of type R₂NMgR' (2) and (R₂N)₂Mg (3). Nevertheless, for achieving high conversions it is usually necessary to use a large excess of the magnesium amides (2-8 equivalents), which complicates further quenching reactions with electrophiles (up to 15 equivalents of electrophile may have to be used). Similarly, the dialkyl amino zincate 4 requires the use of 3.5-4 equivalents of an electrophile in subsequent quenching reactions.

Scheme 1. Typical bases used for the deprotonation of aromatics or heterocycles.

The use of these bases is thus either limited by their poor solubility, or they are not very efficient in view of the amounts of base and the amount of electrophile needed to perform the desired conversion. Their activity or reactivity is very low. The use of lithium salts to increase the solubility of Grignard reagents is known from EP 1 582 523. In this application, the main function of the Grignard reagents of the general formula R^*(MgX)_n-LiY disclosed therein is to perform a halogen/magnesium exchange in either aliphatic or aromatic systems. The Grignard reagent derivatives provide a "nucleophilic carbon atom" at a magnesium-carbon-bond. By the addition of a lithium salt to the Grignard reagent, the reactivity of the Grignard reagents can be increased by forming a magnesiate intermediate. These Grignard reagents then show a higher reactivity and selectivity due to the formation of a magnesiate intermediate.

It is an object of the present invention to provide an inexpensive magnesium base which is highly soluble and more reactive. A further object of the present invention is to provide a magnesium base showing a high kinetic activity and a high selectivity.

These objects are achieved by the features of the independent claims. Preferred embodiments are set forth in the dependent claims.

Surprisingly, it was found and reported in an older patent application published as EP 1810974 Al that mixed magnesium and lithium amides of type R¹R²N-MgX-ZLiY (I) can be prepared by reacting an amine R¹R²NH with a Grignard reagent R'MgX in the presence of LiY or with R'MgX-zLiY in a solvent.

R , R and R' independently are selected from substituted or unsubstituted aryl or heteroaryl containing one or more heteroatoms, linear, branched or cyclic, substituted or unsubstituted alkyl, alkenyl, alkynyl, or derivatives thereof, and, for R¹ and R² only, the silyl derivatives thereof. One of R¹ and R² may be H; or R¹ and R² together can be part of a cyclic or polymeric structure.

X and Y independently are selected from the group consisting of F; Cl; Br; I; CN; SCN; NCO; HaIO_n , wherein n = 3 or 4 and Hal is selected from CI, Br and I; NO₃; BF₄; PF₆; H; a carboxylate of the general formula R^XCO₂; an alcoholate of the general formula OR^X; a thiolate of the general formula SR^X; R^XP(O)O₂; or SCOR^X; O_nSR^x, wherein n = 2 or 3; or NO_n, wherein n = 2 or 3; and a derivative thereof; wherein R^x is a substituted or unsubstituted aryl or heteroaryl containing one or more heteroatoms; linear, branched or cyclic, substituted or unsubstituted alkyl, alkenyl, alkynyl, or derivatives thereof; or H.

X and Y may be identical or different. In the above given context, z > 0.

The amides of formula I can also be prepared in an alternative way by reacting a lithium amide of the formula R¹R²NLi with a magnesium salt of the form MgX₂ or Mg XY. This reaction is preferably carried out in a solvent. In order to achieve a compound of formula I, the magnesium salt and the lithium amide are reacted in approximately equimolar ratio. Thus, the ratio of lithium amide to magnesium salt is usually in the range of 1:0.8-1.2, preferably in the range of 1:0.9-1.1, and most preferably in the range of 1:0.95-1.05.

The amides of formula I are not part of the present invention.

Now, additionally, the inventors found that magnesium bisamides of the general formula

R¹R²N-Mg-NR³R⁴^zLiY (II)

can be prepared. In this formula, R¹, R², R³, and R⁴ are, independently, selected from H, substituted or unsubstituted aryl or heteroaryl containing one or more heteroatoms, linear, branched or cyclic, substituted or unsubstituted alkyl, alkenyl, alkynyl, or silyl derivatives thereof; and R¹ and R² together, and/or R³ and R⁴ together can be part of a cyclic or polymeric structure; and wherein at least one of R¹ and R² and at least one of R³ and R⁴ is other than H.

X and Y are, independently, selected from the group consisting of F; Cl; Br; I; CN; SCN; NCO; HaIO_n , wherein n = 3 or 4 and Hal is selected from Cl, Br and I; NO₃; BF₄; PF₆; H; a carboxylate of the general formula R^XCO₂; an alcoholate of the general formula OR^X; a thiolate of the general formula SR^X; R^XP(O)O₂; or SCOR^X; or SCSR^X; O_nSR^x, wherein n = 2 or 3; or NO_n, wherein n = 2 or 3; and a derivative thereof; wherein R^x is a substituted or unsubstituted aryl or heteroaryl containing one or more heteroatoms, linear, branched or cyclic, substituted or unsubstituted alkyl, alkenyl, alkynyl, or derivatives thereof, or H; In the above given formula II, z > O. The adduct with a solvent should also be encompassed by any of the compounds of formula II.

The bisamides of the general formula II can be prepared from the monoamides of formula I. When reacting R¹R²N-MgX-ZLiY with R³R⁴NLi, a bisamide of formula II is formed. This reaction is equivalent to a reaction of a generally known Grignard reagent R 'MgX in the presence of an amine R¹R²NH, and subsequently with R³R⁴NLi. The lithium may also be added as a lithium salt in the form LiY, especially when the Grignard reagent or the monoamide are not complexed with a lithium salt. Obviously, the reagent may also be of the form R R N-MgX-zLiY, wherein a lithium salt is already present with the monoamide. In this way, bisamides may be prepared, wherein the two amides are different. However, the two amides may also be the same.

In a preferred embodiment of the present invention, the two amides are different, i.e. R¹R²N is not the same as R R N. The reactivity and selectivity of the mixed magnesium lithium amides strongly depends on the one of the two amides. If both amides are identical, the difference in reactivity and selectivity can not be seen. However, if both amides differ, one of the two amides is responsible for the reactivity of the complex compound. In such a case, one of the two amide functions may be a cheap and easily introducible amide, and the other amide function may be selected for the good reactivity and selectivity. In a specifically preferred embodiment of the present invention, one of the amides is TMP and the other is diisopropylamide.

In the following description, the magnesium amides containing two amides are referred to as bisamides, irrespective of the fact that the two amides may also be different. In the latter case, i.e. when the two amides are different, these magnesium amides may also be referred to as magnesium diamides, or heteroamides. When the two amide functions are identical, the magnesium amide may be termed as homoamide.

Alternatively, the bisamides may be prepared by reacting two lithium amides R¹R²NLi and R³R⁴NLi with a magnesium salt MgX₂. If both lithium amides are identical, or a magnesium monoamide is reacted with a lithium amide of the same type, a bisamide of the general formula Mg(NR 'R²)₂-zLiY will result. For a higher solubility of the magnesium salt MgX₂, this salt may be prepared in situ, for example as described below.

Even though X is not present in formula II, it is defined above as it is used in the preparation of compounds of formula II. X may be selected from the same group as Y and may be different or identical to Y.

The bisamides of the present invention show an increased solubility and a high reactivity. Unlike Grignard reagents, which can perform halogen/magnesium exchanges, the amides of the present invention are bases which will tolerate many functional groups, especially halogen substituents. This is due to the different nature of the nitrogen magnesium bond present in the amides of the present application in view of a carbon magnesium bond as in Grignard reagents. The increase in reactivity of the Grignard reagents in the presence of a lithium salt is due to the formation of magnesiate intermediates. In contrast thereto, however, the lithium salt which is added to the amides according to the present application prevents the formation of aggregates. The formation of aggregates is a well known problem in the background art in relation to magnesium amides. As a consequence, the amides known so far have to be used in high excess as they are not very reactive. As the amides of the present invention are not present as aggregates due to the presence of a lithium salt, the amides are much more reactive and more soluble than the amides known so far.

Many common solvents can be used in the present invention, m principle, any solvent capable of dissolving the specific amine and the Grignard reagent used as starting materials and the resulting products. In a preferred embodiment of the present invention, the solvent is selected from cyclic, linear or branched mono or polyethers, thioethers, amines, phosphines, and derivatives thereof containing one or more additional heteroatoms selected from O, N, S and P, preferably tetrahydrofuran (THF), 2-methyltetrahydrofuran, dibutyl ether, diethyl ether, tert-butylmethyl ether, dimethoxyethane, dioxanes, preferably 1,4-dioxane, triethylamine, ethyldiisopropylamine, dimethylsulfide, dibutylsulfide; cyclic amides, preferably N-methyl-2- pyrrolidone (NMP), N- ethyl- 2-pyrrolidone (NEP), N-butyl-2-pyrrolidone (NBP); cyclic, linear or branched alkanes and/or alkenes wherein one or more hydrogens are replaced by a halogen, preferably dichloromethane, 1,2-dichloroethane, CCl₄; urea derivatives, preferably N,N'-dimethylpropyleneurea (DMPU); aromatic, heteroaromatic or aliphatic hydrocarbons, preferably benzene, toluene, xylene, pyridine, pentane, cyclohexane, hexane, heptane; hexamethylphosphorus triamide (HMPA), CS₂; or combinations thereof.

The process for the preparation of amides of formula I, which is not part of this application, is carried out by reacting an amine R¹R²NH with a Grignard reagent R'MgX in the presence of LiY or with R'MgX-zLiY in a solvent. The materials are contacted preferably at room temperature for the minimum time necessary to provide the desired yield. Temperatures between O⁰C and 50⁰C are preferred, however, higher or lower reaction temperatures are also suitable. The preparation of the bisamides of formula II is usually carried out at temperatures between -40⁰C and 5O⁰C, preferably in the range of ~20°C to 30⁰C and most preferred at around 0⁰C. A person skilled in the art will, however, be able to select a suitable temperature for the preparation of the amides of formula I or II by routine experimentation.

In another preferred embodiment, X and Y are independently or both Cl, Br or I, and preferably Cl.

Preferably, the preparation of a compound of formula I is achieved by /PrMgCl-LiCl^[5]. This process is particularly preferred since iPrMgCl-LiCl is commercially available.

Generally, any Grignard reagent can be used to prepare the mixed Mg/Li-amides in the presence of any lithium salt. It is nevertheless preferred to use a Grignard reagent the side or by-products of which can easily be removed from the reaction mixture. The presence of a lithium salt accelerates the exchange reaction compared to homoleptic reagents RMgX and R₂Mg without the use of a lithium salt.

According to a second aspect, the present invention is directed to a mixed Mg/LΪ bisamide of the general formula R¹R²N-MgNR³R⁴ ZLiY (II), wherein R¹, R², R³, R⁴, Y and z are defined as above. It is to be understood that the adduct of a solvent is also comprised by any of these formulae.

A third aspect of the present invention is directed to a solution of the amide (II) in a solvent. The solvent can be any suitable solvent capable of dissolving the amide. Especially preferred solvents are the solvents listed above for the preparation of the amides. AU aspects and features described above in relation to the first aspect shall also apply to the second and third aspect of the invention.

In a preferred embodiment of the present invention, the solvent used to dissolve the mixed amides or used for the solvent adduct of the mixed amides contains a Lewis base. A Lewis base in the understanding of the present application is a molecule having an electron lone pair in a bonding orbital. A specifically preferred Lewis base for the amides of the present invention is THF. Other preferred Lewis bases may be selected from 2-methyl THF, dioxane, mixtures of THF and/or 2-methyl THF with dioxane, mixtures of pentane and/or hexane with THF and/or 2-methyl THF, and any mixture of the compounds, selected from diethylether, diisopropylether, di-n-butyl ether, cyclopentylmethyl ether, methyl tert-butyl ether, THF and 2-methyl THF.

In another preferred embodiment of the present invention, the Lewis base is present in an amount of 4-30 eq, preferably in an amount of 4.5-20 eq, even more preferably in an amount of 5-15 eq, and most preferably in an amount of 5-10 eq, in relation to the amount of Mg in the amide. With such a high amount of Lewis base, stable mixed amides can more easily be produced and can be maintained without any deterioration for longer times.

In a fourth aspect, the present invention is related to the use of mixed Mg/Li amides (II). The amides of the present invention can be used to remove acidic protons. The deprotonated species can then subsequently be quenched with an electrophile. In principle it is possible to use all kinds of electrophiles that are, for example, cited in the following references, but are not limited thereto:

a) Handbook of Grignard reagents; edited by Gary S. Silverman and Philip E. Rakita (Chemical industries; v. 64). b) Grignard reagents New Developments; edited by Herman G. Richey, Jr., 2000, John Wiley & Sons Ltd. c) Methoden der Organischen Chemie, Houben-Weyl, Band XIII/2a, Metallorganische Verbindungen Be, Mg, Ca, Sr, Ba, Zn, Cd. 1973. d) The chemistry of the metal-carbon bond, vol 4. edited by Frank R. Hartley. 1987, John Wiley & Sons. The bis amides of the present invention combine a high reactivity at a high selectivity or tolerance towards other functional groups within a molecule. Especially, this effect can be seen with aromatic reagents substituted with sensitive functional groups. These aromatic, or heteroaromatics, need a highly reactive base to be deprotonated, and at the same time, the base has to tolerate other functional groups like esters or mtriles. Benzonitrile or benzoic acid esters are examples of such compounds. These aromatic compounds can be deprotonated with common bases like LDA, LiHMDS oder n-Buhi, however, the bases will not tolerate any other functional groups within the reagent. On the other hand, magnesium monoamides like TMPMgCl-LiCl are too unreactive to deprotonate the aromatic reagent. As a consequence, the base has to be added in a high surplus, needing a surplus of the electrophile. The new bisamides of the present invention give a solution to this problem as these compounds combine a high reactivity at a high selectivity.

A preferred embodiment of the present invention refers to the use of magnesium bisamides of the present invention for the deprotonation of aromatics and heterocycles. Preferably, the aromatics or heterocycles are substituted with a phosphorodiamidate, more preferably with tetramethylphosphorodiamidate, Phosphorodiamidates can be used as directing metalation groups (DMG) and allow a substitution pattern of the aromatics or heterocyles which would otherwise not be possible.

The final aspect of the invention relates to the product of the reaction of an electrophile with a substrate which has been deprotonated with a reagent of the general formula II.

In relation to the bisamide of formula II, z is preferably in the range of from 0.01-5, more preferably, z > 1, more preferably, z is in the range from 1 - 5, more preferably from 0.5 - 2.5, further more preferably from 1.5 to 2.5, even more preferably from 1.8 to 2.2, even further more preferably from 1.9 to 2.1, still even more preferably from 1.95 to 2.05, and most preferred about 2.

The inventors of the present invention surprisingly found that the lithium salt is most preferably used in an equal amount in relation to the amide function of the bisamide. For the bisamides, the amount of lithium salt is thus most preferably about 2, however, a slight deviation of this optimum value still leads to acceptable results. The present invention is described in the following on the basis of specific examples. Especially, i-PrMgCl is used as Grignard reagent. However, it is to be understood that the present invention is not limited to such examples.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. All publications and other references mentioned herein are incorporated by reference in their entirety.

As used herein, the terms "alkyl", "alkenyl" and "alkynyl" refer to linear, cyclic and branched, substituted and unsubstitued C₁-C_2O compounds. Preferred ranges for these compounds are C₁-Ci₀, preferably C]-C₅ (lower alkyl) and C₂-Ci₀ and preferably C₂-C₅, respectively, for alkenyl and alkynyl. The term "cycloalkyl" generally refers to linear and branched, substituted and unsubstitued C₃-C_2O cycloalkanes. Here, preferred ranges are C₃- Ci5, more preferably C₃-C₈.

Whenever any of the residues R¹, R², R³ and/or R⁴ are substituted by a substituent, the substϊtuent may be selected by a person skilled in the art from any known substituent. A person skilled in the art will select a possible substituent according to his knowledge and will be able to select a substituent which will not interfere with other substituents present in the molecule and which will not interfere or disturb possible reactions, especially the reactions described within this application. Possible substituents include without limitation halogenes, preferably fluorine, chlorine, bromine and iodine; aliphatic, alicyclic, aromatic or heteroaromatic hydrocarbons, especially alkanes, alkylenes, arylenes, alkylidenes, arylidenes, heteroarylenes and heteroarylidenes; carbonxylic acids including the salts thereof; carboxylic acid halides; aliphatic, alicyclic, aromatic or heteroaromatic carboxylilc acid esters; aldehydes; aliphatic, alicyclic, aromatic or heteroaromatic ketones; alcohols and alcoholates, including a hydroxyl group; phenoles and phenol ates; aliphatic, alicyclic, aromatic or heteroaromatic ethers; aliphatic, alicyclic, aromatic or heteroaromatic peroxides; hydroperoxides; aliphatic, alicyclic, aromatic or heteroaromatic amides or amidines; nitriles; aliphatic, alicyclic, aromatic or heteroaromatic amines; aliphatic, alicyclic, aromatic or heteroaromatic imines; aliphatic, alicyclic, aromatic or heteroaromatic sulfides including a thiol group; sulfonic acids including the salts thereof; thioles and thiolates; phosphonic acids including the salts thereof; phosphinic acids including the salts thereof; phosphorous acids including the salts thereof; phosphinous acids including the salts thereof;

The substituents may be bound to the residues R¹, R², R³ and/or R⁴ via a carbon atom, an oxygen atom, a nitrogen atom, a sulfur atom, or a phosphorus atom. The hetero atoms in any structure containing hetero atoms, as e.g. hetero arylenes or heteroaromatics, may preferably be N, O, S and P.

When R¹ and R², or R³ and R⁴ can be part of a cyclic structure, it is to be understood that R¹ and R² together, or R³ and R⁴ together, are a divalent saturated or unsaturated, linear or branched alkyl, alkenyl or alkynyl which forms in connection with the nitrogen atom of the amide a cyclic secondary amide. An example of such a cyclic amide is the amide of TMPH. Further, the residues R¹ and R², and/or R³ and R⁴ can be part of a polymeric structure. The nitrogen atom of the amide is the connected to a polymeric backbone which may even contain more than one nitrogen atom for the formation of an amide according to the invention.

The term "aryl" as used herein refers to substituted or unsubstituted C₄-C₂₄ aryl. By "heteroaryl", a substituted or unsubstituted C₃-C₂₄ aryl, containing one or more heteroatoms as B, O, N, S, Se, P, is meant. Preferred ranges for both are Q-C1₅, more preferably C₄-Q₀ and includes aryls and fused aryls with or without heteroatoms. A preferred ring size comprises 5 or 6 ring atoms.

Mixed magnesium and lithium amides R¹R²NMgCl-LiCl (R¹ and R² = /-Pr or R¹R²N = 2,2,6,6-tetramethylpiperidyl) can be prepared by reacting (-PrMgCl -LiCl ^[4'^5] with diisopropylamine or 2,2,6,6-tetramethylpiperidine (TMPH), respectively, in THF (-20⁰C - 80°C, for 0.1-48 h ). The resulting Li/Mg-reagents 5a (R¹ and R² = *-Pr) and 5b (R¹R²N = 2,2,6,6-tetramethyIpiρeridyl) proved to have an excellent solubility in THF (0.6 M and 1.2 M, respectively) as well as an improved kinetic acidity and regioselectivity for the magnesation of various aromatics and heterocycles.

An overview over the increased selectiviy and selectivity can be seen from Scheme 1 a below. Here, the same substrates were reacted with a mono amide and a bisamide, and the yields of the respective reactions is given in the scheme. The base indicated above the reaction arrow in the scheme is the corresponding amide indicated in the right column of the scheme. LiCI: 7 % LiCI: 80 %

s %

TMPMgCI-LiCI: Traces TMP₂Mg-2LiCi: 70 % s %

Scheme Ia: Comapπson of reactivity and selectivity of mono amide and bisamide.

The activity of the amides (I) can be shown on the basis of the magnesiation of isoquinoline. Diisopropylamido magnesium chloride-lithium chloride 5a leads to the magnesiated isoquinoline 6 after 12 h reaction time at 25°C and by using 2 equivalents of the base. After iodolysis, the iodoisoquinoline 7a is isolated in 88% yield (Scheme 2). Even more active is the sterically more hindered and less aggregated 2,2,6,6-tetramethylpiperidino magnesium chloride-lithium chloride reagent 5b. It leads to a complete magnesiation within 2 h at 25°C. Remarkably, with this base only 1.1 equivalents are required to achieve a complete metalation. The resulting Giϊgnard reagent 6 provides after iodolysis the iodoisoquinoline 7a in 96% yield (Scheme 2 and Table 1).

/-Pr₂NMgCI-LiCI 5a, (2 equiv)

THF, 25 ⁰C, 12 h -LiCI ^THF' ²⁵ °^C- ^{2 h}

6: >90 %

Scheme 2. Magnesiation of isoquinoline

After the magnesation of a reagent, it can be subjected to a transmetalation. After e.g. a transmetalation with CuCN-2LiCl (20 mol %), the addition of benzoyl chloride (1.2 equiv.) provides the ketone 7b in 86% yield (entry 2 of Table 1).

The presence of an excess of magnesium amides often hampers the performance of palladium-catalyzed cross-couplings. The inventors found that the Grignard reagents generated by deprotonation with 5b (1.1 equiv.) such as 6 are readily transmetalated to the corresponding zinc derivative (ZnCl₂ (1.1 equiv.), 0⁰C, 5 min.) and undergo a Negishi-cross- coupling reaction using Pd(dba)₂ (5 mol%) (dba = dibenzylideneacetone), P(2-fur)₃ (7 mol%) (fur=furyl) with ethyl 4-iodobenzoate (1.2 equiv.; 50°C, 12 h) leading to the arylated quinoline (7c) in 82% yield. This behaviour is general and 3-bromoquinoline is metalated with 5b (1.1 equiv., -30°C, 0.5 h) leading to the 2-magnesiated quinoline 8 (entries 4 and 5 of Table 1). Thus, the quenching of 8 with I₂ and N,N-dimethylformamide (DMF) provides the two quinolines 9a and 9b in 96-93% yield.

Whereas the deprotonation of 2,6-dichloroρyridine with /-Pr₂NMgCl-LiCl 5a and lithium diisopropylamide (LDA)^[8j] provides a 1:1 mixture of 3- and 4-magnesiated 2,6-dichloro- pyridine, the use of TMPMgCl-LiCl 5b furnishes only the 4-magnesiated pyridine 10. Its reaction with typical electrophiles (I₂, DMF and PhCHO) provides the expected products lla- c in 84-93% yield (entries 6-8 of Table 1). Interestingly, metalation of 3,5-dibromopyridine with LDA proceeds selectively at 4-position^E6b] while in the case of (TMPMgCl-LiCl 5b 1.1 equiv, -20⁰C, 0.5h) regioselective metalation of 3,5-dibromopyridine is observed leading after the reaction with DMF to the pyridylaldehyde 13 in 95% yield (entry 9 of Table 1).

The magnesiation of heterocycles bearing more acidic protons'⁷¹ such as thiazole, thiophene, furan, benzothiophene or benzothiazole proceeds smoothly between 0⁰C and 25°C leading to the organomagnesium derivatives 14a-c and 16a-b. After trapping with standard electrophiles, the expected products 15a-c and 17a-b are obtained in 81-98% yield (entries 10-14 of Table 1).

The metalation of pyrimidine derivatives is a challenging problem due to the propensity of these heterocycles to add organometallic reagents. ^t8] The inventors found that the inverse addition of the pyrimidine derivatives 18-20 to a THF solution of 5b (1.05 equiv.) at -55°C for approx. 5 min. provides the corresponding magnesiated derivatives 21-23 in 83-90% yields as indicated by iodolysis experiments leading to the iodinated pyrimidines 24-26

(scheme 3).

Scheme 3. Regioselective magnesiation of pyrimidines

The mixed magnesium-lithium amide 5b is also well suited for the regioselective metalation of polyfunctional aromatic systems. Thus, the reaction of 2-phenylpyridine 27 in THF at 55°C with 5b (2.0 equiv.) for 24 h provides the Grignard reagent 28 showing a rare case where a phenyl ring is preferentially metalated compared to a pyridine ring. After iodolysis, the ortho- iodinated product 29 is obtained in 80% yield. Interestingly, the metalation of polyfunctional aromatics such as the bromodiester 30 also succeeds using only the stoichiometric amount of base 5b (1.1 equiv.) in THF (-30⁰C, 0.5 h) leading regioselectively to the arylmagnesium species 31 which after iodolysis furnishes the polyfunctional aromatic derivative 32 in 88% yield.

27 28 29: 80 %

30 31 32: 88 %

Scheme 4. Regioselective magnesiation of polyfunctional aromatic systems

A solution of TMPMgCl-LiCl can easily be prepared in THF due to its excellent solubility and it is stable for more than 6 months at 25°C. The use of TMPMgCl-LiCl allows for the regioselective functionalization of various aromatics and heteroaromatics. It gives access to new magnesium species not readily available via a Br/Mg-exchange reactions or by previously reported metalation procedures.

The residues R¹ and R² are not limited to organic compounds. R¹ and R² may also be silylated compounds like trimethylsilyl. The preparation of the bϊs(trimethylsilyl) amide 33 can be achieved by reacting bis(trimethylsilyl)amine with i-PrMgCl LiCl at room temperature (see Scheme 5). This base can efficiently be used to deprotonate ketones like e.g. cyclohexanone as can be seen from Scheme 5. Scheme 5: Preparation and use of silylated magnesium amide

The Grignard reagents can also be used to prepare a polymeric base. 2,2,6, 6-Tetramethyl piperidine (TMPH) is a well known base. It can be used to prepare the corresponding mixed Mg/Li amide TMPMgCl-LiCl 5b. This monomeric base is very reactive but also very expensive. A corresponding polymeric base to TMPH is chimassorb 994, the structure of which is shown in Scheme 6.

Chimassorb 994

Scheme 6: Structure of chimassorb 994

Chimassorb 994 can be used to prepare the corresponding mixed Mg/Li amide by reacting chimassorb 994 with j-PrMgCl-LiCl at room temperature (see Scheme 5). This base 34 is stable and soluble in THF before and after deprotonation. As being a polymeric base, it can be easily removed after completion of the reaction. Since chimassorb 994 is much cheaper than TMP, a corresponding base can be prepared at reduced costs. The polymeric base 34 shows slightly lower activity than monomeric TMPMgCl-LiCl but is nevertheless very effective in deprotonating compounds with acidic protons like isoquinoline. A corresponding example is shown in Scheme 7. The polymeric base can be used to deprotonate various substrates. For example, isoquinoline reacts at room temperature with the base 34 affording after quenching with iodine 1-iodoisoquinoline 7a.

Scheme 7: Preparation and use of the mixed Mg/Li amide of chimassorb 994

The above given examples show that the new mixed Mg/Li-bases of the general type RR¹RR²NNMMggXX--ZzLLiiYY hhaavvee aa hhiigghh kkiinneettiicc aaccttiivviittyy dduuee to the presence of a lithium salt which breaks oligomeric aggregates of magnesium amides.

An example of a symmetrical bisamide reagent is (TMP)₂Mg-2LiCl 40a. It is prepared by reacting in situ generated MgCl₂ with lithium 2,2,6,6-tetramethylpiperidide (TMPLi) in THF at O⁰C for 30 minutes (see Scheme 8).

40a

Scheme 8: Preparation of the bisamide (TMP)₂Mg-2LiCl (40a).

Additionally, other symmetrical bisamides can be prepared in high yields using the same methodology as for the preparation of 40a. All examples shown below (40b-40c) were prepared in >95% yield (Scheme 9) in analogy to the preparation of 40a. This also includes bisamides containing silyl substituted amines.

40b 40c 4Od 40e 40f

Scheme 9: Further examples of symmetrical bisamides.

Comparative metalation experiments on aromatic substrates were performed under identical conditions with 1.1 equivalents of both (TMP)₂Mg-2LiCl (40a) and TMPMgCl-LiCl (5b). The bisamide reagent (TMP)₂Mg^LiCl shows highly superior reactivity than TMPMgCl-LiCl and it was even able to deprotonate very weak acidic substrates.

Scheme 10 gives an overview over examples of reactions of four different aromatic substances (41-44) with (TMP)₂Mg- 2LiCl (40a) and TMPMgCl-LiCl (5b) under identical conditions. The respective yields are indicated for the products of each of the two amides 40a and 5b. This experiment clearly shows the even superior reactivity of the bisamides in view of the monoamides. All reactions are carried out at room temperature (rt) being at 25°C.

41 TMPMgCLLiCI = 7% 41a {TMP)₂Mg.2LiCI = 80%

42 TMPMgCLLiCI = traces 42a (TMP)₂Mg.2LiCI = 83%

43 TMPMgCLLiCI = traces 43a (TMP)₂Mg.2LiCI = 77%

Scheme 10: Comparison of reaction of aryls with monoamide 5b and bisamide 40a.

Additionally, the resultant Grignard intermediates derived from (TMP)₂Mg- 2LiCl show good stability and tolerance to various substrates. Furthermore, they react with different eletrophiles providing the corresponding functionalized derivatives in good yields. Examples are shown in Table 2 below.

It could also be shown that mixed magnesium bases bearing two different amide functions, i.e. R¹R²N and R³R⁴N being different, have improved properties over the con'esponding symmetrical reagents bearing two identical amide functions. The unsymmetrical reagents 40e-40i are prepared from TMPMgCl LiCl, /-Pr₂NMgCl-LiCl and (2- ethyl-hex Vl)₂NMgCl -LiCl'⁹¹, respectively, and the corresponding lithium species of lH-benzotriazole (Bt), 5,6-dimethyl-lH-benzotriazole (DMBt) and carbazole (CBZ), respectively (Scheme 11).

4Oe (R=H) 4Of (R=Me)

4Og

LiCI

4Oh (R=Z-Pr)

4Oi [Bis(2-ethylhexyl)]

Scheme 11: Preparation of compound 40e-40i having two different amide functions.

Especially, the base 4Oe provides a far higher reactivity than TMPMgCl-LiCl (5b) and (TMP)₂Mg- 2LiCl (40a) when using special directing metalation groups (DMG). TMPMgCl LiCl provides full metalation of 44 in 90 minutes at 0°C, and reagent 40a provides full metalation in 60 minutes. In contrast thereto, the use of 4Oe provides full metalation at 0°C in only 10 minutes. Furthermore, only 1.3 equivalents of the base 4Oe are used in contrast to 1.5 equivalents of TMPMgCl-LiCl. Moreover, the yield of 44a is higher compared to the use of TMPMgCl-LiCl (Scheme 12).

44 44a: 73%

44 44a: 91 %

Me₂J₂

44 44a

Scheme 12: Comparison of the reactivity of unsymmetrical bisamide 4Oe in view of monoamide 5b and symmetrical bisamide 40a.

The regulating intermediates derived from (TMP)Mg(Bt)-2LiCl show good stability and tolerance to various substrates. They can be trapped with an electrophile like iodine to provide the corresponding functional ized derivatives in good yields. Examples are shown in Table 3.

The compounds of the present invention can also be used in connection with a phosphorodiamidate group on an aryl or heteroaryl. This effect will be shown in the following with the N,N,N',N'-tetramethylphosphorodiamidate ((Me₂N)₂P(O)O-) group, but is not limited to this specific group. As a person skilled in the art will recognize immediately, other directing metalation groups can also be used, especially other phosphorodiamidate groups.

Ortho-ditectεd metalation is an important method for the functionalization of various aromatics and heterocycles. Various DMG (directed metalation groups) have been used for achieving efficient lithiations. The DMG allow for a fast and ort/io-selective metalation mainly by chelation (entropic effect). Polar DMG may furthermore transfer electron density to the metal base and increase their metalating power. Recently, magnesiate bases have proven to be of great structural and synthetic interest for the functional! zation of aromatics.

As was shown above, mixed Li, Mg-bases like TMP₂Mg-2LiCl are highly active and soluble magnesium bases allowing for smooth metalations of various aromatics and hetero cycles with an excellent functional group compatibility. Surprisingly, the inventors found that the DMG N,N,N',N'-tettamethyIphosphorodiamidate ((Me₂N)₂P(O)O-) is a very strong directing group for magnesiation an it may overrule the effect of other substituents present in the aromatic substrate. In contrast to directed lithiations, which have usually to be perfomed at -105 ⁰C to avoid Fries-type rearrangements, the magnesiation with TMP₂Mg^LiCl takes place (even at 0⁰C) without anionic migration of the tetramethylphosphorodiamidate group. This would allow new types of functionalization such as formal meta- or pαra-functionalization (Scheme 13).

61 63 65

Scheme 13: Meta, para- and para, metø-functionalization using TMP₂Mg*2LiCl

Thus, the inventors have found that a range of aromatic phosphorodiamidates bearing either a functional group (FG) in theparα-position (type 60) or in the meta-position (type 61) undergo an efficient magnesiation with TMP₂Mg*2LiCl (40a) leading respectively to the products of type 62 and 63 after the addition of an electrophile. Substitution of the OP(O)(NMe₂)₂ group with a nucleophile (Nu) gives meta, para- and para, metø-difunctionalized molecules of type 64 and 65 as described below (Scheme 13 and Table 4). The magnesiation of substrates 61 and 62using TMP₂Mg'2LiCl (40a) proceeds smoothly within a few hours at 0 ⁰C for cyano- and ester-substituted phosphorodiamidates 60a and 61a (entries 1-3, 10-13).

For halogen-substituted starting materials (60b, 60c and 6Od; entries 4-9) as well as for the trifluoromethyl-substituted phosphorodiamidate 61b (entry 14), lower temperatures (-40 to - 50 °C) led to optimum results. In general, the regioselectivity of the metalation of aromatics is governed by a combination of electronic and/or sterical effects. However, the tetramethylphosphorodiamidate group is one of the strongest donor in organic synthesis and activates the Mg-N bond giving to the base an ate character (Scheme 14).

Scheme 14: Efficient /rørø-metalation due to the ate character of TMP₂Mg-2LiCl (40a);(LiCl has been omitted for the sake of clarity).

This electronic effect increases the metalation power of the base and no additional chelation or inductive effects are necessary for achieving the magnesiation. Normally, this phosphorodiamidate-triggered magnesiation preferentially occurs at the sterically less hindered position of the aromatic ring promoting formal m^ω-metalation. However, in the case of meta- substituted substrates bearing bromo, chloro and fluoro as one of the functional groups, the inventors observed that the regioselectivity of the metalation is affected by the competitive directing effects of these halogens. Various electrophiles such as acid chlorides, TsCN, allylic halides, aldehydes or aromatic iodides react with the magnesium organometallic intermediates providing the desired products in 72 - 90% yields (Table 4). In the case of allylation and acylation reactions, the best results were obtained when the arylmagnesium species were transmetalated with ZnCl₂ (1.2 equiv) and CuCN*2LiCl (0.5 - 1.3 equiv) prior to the addition of the acid chloride, TsCN or the allylic halide (entries 2-4, 7, 8 and 12). Similarly, Negishi cross-couplings with aryl iodides in the presence of Pd(dba)2 (2 mol%) and P(2-fur)₃ (4 mol%) were successfully performed after transmetalation of the Grignard- reagents with ZnCl₂ (entries 1, 5, 6 and 13). A double functionalization in meta, meta '- positions has also been achieved. Thus, the treatment of the nitrile 60a with TMP₂Mg^LiCl (1.1 equiv, 0 ⁰C, 4 h) followed by a copρer(I)-catalyzed reaction with t-BuCOCl provides the ketone 62a in 81% yield. By applying the same reaction sequence (metalation at -60 ⁰C for 0.5 h), the ketone 62a was converted to the diketone 66a in 77% yield. Furthermore, the double functionalization of the bromo- and chloro-substituted phosphorodiamidates 60b and 6Od led to the preparation of the highly functionalized phosphorodiamidates 66b and 66c in good overall yields, showing the high directing power of the OP(O)(NMe₂)₂ group (Scheme 15).

min f-BuOC 0C

min °C

Scheme 15: Double functionalization of phosphorodiamidates 60a, 60b and 6Od, leading to meta, meta '-substituted products (66a-c).

The further manipulation of the functionalized aryl phosphorodiamidates of type 62 and 63 was best achieved by converting these intermediates into derived fluorinated sulfonates such as nonaflates or triflates. Thus, a microwave assisted deprotection of aryl phosphorodiamidates 62b and 62c with formic acid in aqueous ethanol (120 ⁰C, 30 min) provides polyfunctional phenols, which after the reaction with C₄FgSO₂F (NaH, Et₂O, 25 ⁰C, 12 h) allowed the isolation of the corresponding nonaflates 67a and 67b in 71% yield (Scheme 4). A nickel-catalyzed cross-coupling of nonaflate 67a with the arylzinc reagent 69 afforded the biphenyl 68a in 90% yield. On the other hand, reaction of 67b with dimethylamine-borane complex in the presence of catalytic amount of Pd(PPh₃)₄ gave the reduced derivative 68b in 94% yield. Similarly, the aryl phosphorodiamidate 63b was successfully converted to the diester 68c and to the ketoester 68d in 74% and 95% yield respectively, showing that this reaction sequence allows either efficient functionalization or removal of the directing metalation group (Scheme 16).

(5 mol%) 3 h 68a: 90 %

16 h 68b: 94 %

mol%) 3 h

Scheme 16: Microwave assisted deprotection of the aryl phosphorodiamidates for further functionalization or DMG removal.

In summary, this approach allows to achieve new functionalization pattern of aromatics by performing magnesiations using the powerful TMP₂Mg*2LiCl base (40a) combined with the phosphorodiamidate (-OP(O)(NMe₂)₂) as strong directing metalation group. This methodology allows a general preparation of various meta-, para- and meta, meta'- polyfunctionalized aromatics which are not easily accessible by using conventional synthetic strategies. Applications toward the synthesis of biologically active molecules seem to be feasible with this approach.

As can be seen from the above given examples, the new mixed Mg/Li-bases are very effective in deprotonating organic compounds. The deprotonation can be achieved in different solvents and can preferably be conducted at temperatures between -9O⁰C and 100⁰C. Further, due to the effective deprotonation reaction, the amides of the present invention preferably only require the use of 0.9-5 equivalents, more preferably 1-2 equivalents and most preferably 1.1-1.5 equivalents per proton to be deprotonated.

With this new type of base, which is highly soluble and the side products of which do not disturb the following reactions, many new products may be obtained, or known reactions pathways will be more efficient. A person skilled in the art will easily recognise the benefit of the new Mg/Li-base and will be able to use this base in a wide variety of chemical reactions,

In the following, examples are given to illustrate the present invention. However, these examples are given for illustrative purposes only and are not supposed to limit the scope of the invention which is determined by the claims below.

Experimental Section:

Preparation of the reagent TMPMgCl LiCl (5b):

A dry and argon flushed 250 mL flask, equipped with a magnetic stirrer and a septum, was charged with freshly titrated j-PrMgCl-LiCl (10O mL, 1.2 M in THF, 120 mmol). 2,2,6 ,6-tetramethylpiperidine (TMPH) (19.8 g, 126 mmol, 1.05 equiv) was added dropwise at room temperature. The reaction mixture was stirred until gas evaluation was completed (ca. 24 h) at room temperature.

Preparation of 1-iodoisoquinoline (7a):

A dry and argon flushed 10 mL flask, equipped with a magnetic stirrer and a septum, was charged with TMPMgCl-LiCl (5 mL, 1.2 M in THF, 6.0 mmol). Isoquinoline (703 mg, 5.45 mmol) in THF (5 ml) was added dropwise at room temperature. During addition, the reaction mixture became red and the metal ation was complete after 2 h (as checked by GC analysis of reaction aliquots quenched with a solution of I₂ in THF, the conversion was more than 98%). A solution of I₂ in THF (6 ml, 1 M in THF, 6.0 mmol) was slowly added at -20⁰C. The reaction mixture was quenched with sat. aqueous NH₄Cl solution (10 mL). The aqueous phase was extracted with ether (4 x 10 mL), dried with Na₂SO₄ and concentrated in vacuo. The crude residue was purified by filter column chromatography (GE^CVpentane) yielding 1-iodoisoquinoline (7a; 1.33 mg, 96%) as slightly yellow crystals (mp = 74-76°C).

The products listed in table 1 below can be produced according to the preparation of 1-iodoisoquinoline (7a).

Table 1. Products obtained by the magnesiation of heterocycles with TMPMgCl-LiCl (5b) and reaction with electrophiles.

Entry Magnesium τ, t Electophile Product Yield reagent^[al [°C,h]^[b] (%)^[c]

liss. Ji - N

1 25, 2 I₂

MgCI R

6 7a: R = I 96

2 6 25, 2 PhCOCl^[d] 7b:R = COPh 86

3 6 25, 2 7c:R = 4-EtO₂C₆H₄ 82

5 8 -30, 0.5 DMF 9b: R = CHO 93

7 10 25, 0.1 DMF lib: R = CHO 90

8 10 25, 0.1 PhCHO llc:R = CH(OH)Ph 84

Y = CH 15a: R = CHO 81

14b: X = S,

11 25, 24 DMF 15b: R = CHO 90

Y = CH

14c: X = S,

12 0, 0.1 PhCHO 15c:R = CH(OH)Ph 94

Y = N

Y = CH 17a: R = CHO 93

16b: X = S,

14 0, 0.1 17b: R = I 98

Y = N I₂

^[a]Lithium chloride and TMPH are complexed to the Grignard reagent. ^[b]Reaction conditions for the deprotonation with TMPMgCl-LiCl (5b, 1.1 equiv.). ^[c]Isolated yield of analytically pure product. ^[d]A transmetalation with CuCN-2LiCl (0.2 equiv) was performed Preparation of (TMP)₂Mg 2LiCl (40a).

Magnesium turnings (15 mmol) were placed in an argon-flushed- S chlenk flask and THF (30 ml) was added. 1,2-Dichloroethane (16 mmol) was added dropwise and the reaction was stirred until all magnesium was consumed, approximately 2 h. In another argon-flushed- Schlenk flask 2,2,6,6-tetramethylpiperidine (TMPH) (30 mmol) and THF (20 ml) were placed. This solution was cooled to -40°C and n-BuLi (30 mmol) was added dropwise. After the addition, the reaction mixture was warmed to 0⁰C and stirred at same temperature for 30 min. The MgCl₂ solution was then transferred via cannula into the TMPLi solution and the reaction mixture was stirred at 0⁰C for 30 min, then warmed to room temperature and stirred for an additional 1 h. The solvents were removed then in vacuo followed by addition of THF while stirring until complete dissolution of the salts. The fresh (TMP)₂Mg- 2LiCl solution was titrated prior to use at 0⁰C against benzoic acid using 4-(phenylazo)-diphenylamine as indicator.Average concentration in THF was 0,6 mol/1.

Preparation of (PIR)₂Mg 2LiCl (40b).

Prepared according to 40a from pyrrolidine (PIR) (30 mmol), rc-BuLi (30 mmol), magnesium turnings (15 mmol) and 1,2-dichloroethane (16 mmol) in THF. Average concentration in THF was found to be 0,65 nαol/1.

Preparation of (J-Pr)₂NMg 2LiCl (40c).

Prepared according to 40a from diisopropylamine (30 mmol), rc-BuLi (30 mmol), magnesium turnings (15 mmol) and 1,2-dichloroethane (16 mmol) in THF. Average concentration in THF was found to be 0,84 mol/1.

Preparation of (HMDS)₂Mg 2LiCl (4Od).

Prepared according to 40a from 1,1,1,3,3,3-hexamethyldisilazane (HMDS) (30 mmol), n-BuLi (30 mmol), magnesium turnings (15 mmol) and 1,2-dichloroethane (16 mmol) in THF. Average concentration in THF was found to be 0,86 mol/L.

Preparation of (TMP)Mg(Bt) 2Li Cl (4Oe):

Benzotriazole (Bt)(1.19 g, 10.0 mmol) was placed in a flame dried, argon flushed 5O mI Schlenk tube equipped with magnetic stirring bar and septum. THF (10 ml) was added. The solution was cooled to -40⁰C. Then n-BuLi (3.62 ml, 2.76 M in hexane, 10.0 mmol) was added drop wise. White precipitate was formed immediately. After the end of the addition the resulting suspension was stirred at -40⁰C for 30 min. Then solvents were removed in vacuo followed by addition of TMPMgCl LiCl (8.93 ml, 1.12 M in THF, 10.0 mmol). After the complete dissolving of the white solid, THF was removed in vacuo. To the resulting brownish gel, THF was added while stirring until complete dissolution of the salts. The fresh (TMP)Mg(Bt) 2LiCl solution was titrated at room temperature against benzoic acid using 4-(phenylazo)-diphenylamine as an indicator. Average concentration in THF was found to be 0.35 mol/1.

Preparation of (TMP)Mg(DMBt) 2LiCl (4Of):

Prepared according to 4Oe from 5,6-dimethyl-lH-benzotriazole (10 mmol), «-BuLi (10 mmol) and TMPMgCl LiCl (10 mmol) in THF. Average concentration in THF was found to be 0.33 mol/1.

Preparation of (TMP)Mg(CBZ)-2LiCl (4Og):

Prepared according to 4Oe from 9H-carbazole (10 mmol), n-BuLi (10 mmol), TMPMgCl LiCl

(10 mmol) in TΗF. Average concentration in TΗF was found to be 0.33 mol/1.

Preparation of (1-Pr₂N)Mg(Bt) 2LiCI (4Oh):

Prepared according to 4Oe from benzotriazole (10 mmol), rc-BuLi (10 mmol) and 0^"-Pr₂N)MgCrLiCl (10 mmol) in TΗF. Average concentration in TΗF was found to be 0.24 mol/1.

Preparation of (2-ethyl-hexyl)₂NMg(Bt) 2LiCl (4Oi):

Prepared according to 4Oe from benzotriazole (10 mmol), «-BuLi (10 mmol) and (2-ethyl-hexyl)₂NMgClLiCl (10 mmol) in TΗF. Average concentration in TΗF was found to be 0.23 mol/1. Preparation of (/Pr(N)ZBu)₂Mg 2LiCl (4Oj).

Prepared according to 40a from wo-propyl(teλ?-butyl)amine (30 mmol), n-BuLi (30 mmol), magnesium turnings (15 mmol) and 1, 2- dichloro ethane (16 mmol) in THF. Average concentration in THF was found to be 0,80 mol/L.

Preparation of (iPr(N)cHex)₂Mg-2LiCl (40k).

Prepared according to 40a from rsø-propylfc;yc/ø-hexyl)amine (30 mmol), «-BuLi (30 mmol), magnesium turnings (15 mmol) and 1,2-dichloroethane (16 mmol) in THF. Average concentration in THF was found to be 0,60 mol/L

Magnesiations of functionalized arenes with (TMP)₂Mg 2LiCl: Preparation of di-tert-butyl 4-iodobenzene-l,3-dioate (51a).

A dry and nitrogen-flushed 10-mI-Schlenk-flask, equipped with a magnetic stirring bar and a septum, was charged with a solution of the di-tert-butyl isophthalate (278 mg, 1 mmol) in dry THF (1 ml). After cooling to 0⁰C, a freshly prepared (TMP)₂Mg- 2LiCl solution (0.6 mol/1 in THF, 1.83 ml, 1.1 mmol) was added drop wise and the reaction mixture was stirred at the same temperature. The completion of the metalation (2 h) was checked by GC- analysis of reaction aliquots quenched with a solution of I₂ in dry ether. Iodine (508 mg, 2 mmol) dissolved in dry THF (2 ml) was then added at 0⁰C and the resulting mixture warmed to room temperature. After stirring for 1 hour, the reaction mixture was quenched with sat. aq. Na₂S₂O₃, extracted with ether (3 x 20 ml) and dried over Na₂SO₄. After filtration the solvent was removed in vacuo. Purification by flash-chromatography (n-pentane/diethyl ether, 10:1) furnished compound 51a (380 mg, 94%) as a yellow oil.

The products listed in Table 2 below can be produced according to the preparation of di-tert- butyl 4-iodobenzene-l,3-dioate (51a), using the corresponding temperatures and reactions times as indicated in the table. Table 2. Products obtained by the magnesiation of aromatics with (TMP)₂Mg 2LiCl and reactions with eletrophiles.

Entry Substrate Temp. [⁰C] Time Electrophile E^÷ Product Yield

25 Ih PhCOCI' 93%

41 41b: E=COPh

41 25 Ih /?-IPhCθ₂Et^b 41c: E=/?-PhCO₂Et 82%

53 53a: E=I

53 -10 Ih PhCOCl⁰ 53b: E=COPh 52%

45 45a: E=I

45 25 Ih EtCOCP 45b: E=COEt 7%

46: X=H 46a: E=I 47: X=Br -20 3h I₂ 47a: E=I 74%

48 48a: E=I

10 48 -20 4h PhCOCl³ 48b: E=PhCO 62%

42 42b: E=Br 49 49 »a: E=I Entry Substrate Temp.[^QC] Time Electrophile E* Product Yield

13 49 -40 5h BrCl₂C₂Cl₂Br 49b: E=Br 70% f^a]A transmetalation with CuCN-2LiCl was performed. ^Ib]Obtained by palladium-catalyzed cross-coupling after transmetalation with ZnCl₂.

Magnesiations of functionalized arenes with (TMP)Mg(Bt)-2LiCl:

Preparation of ethyl 3-{[bis(dimethyIamino)phosphoryI]oxy}-2-iodobenzoate (44a).

A dry and nitrogen-flushed 25-ml Schlenk flask, equipped with a magnetic stirring bar and a septum, was charged ethyl 3-{ [bis(dimethylamino)ρhosphoryl]oxy}benzoate 44 (300 mg, 1.00 mmol) in dry THF (3 ml). After cooling to 0⁰C, a freshly prepared (TMP)Mg(Bt>2LiCl solution (4.33 ml, 0.3 M in THF, 1.3 mmol) was added dropwise and the reaction mixture was stirred at the same temperature. The completion of the metal ation (10 min) was checked by GC- analysis of reaction aliquots quenched with a solution of I₂ in dry THF. Iodine (508 mg, 2.0 mmol) dissolved in dry THF (2 ml) was then added at 0°C and the resulting mixture warmed to room temperature. After stirring for 1 hour, the reaction mixture was quenched with sat. aq. Na₂S₂O₃, extracted with ether (3 x 20 ml) and dried over Na₂SO₄. After filtration, the solvent was removed in vacuo. Purification by flash-chromatography using ethyl acetate as eluent furnished ethyl 3-{ [bis(dimethylamino)phosphoryl]oxy}-2-iodobenzoate 44a (332 mg, 78%) as a yellow oil.

The products listed in Table 3 below can be produced according to the preparation of ethyl 3-{[bis(dimethylamino)phosphoryl]oxy}-2-iodobenzoate 44a, using the corresponding temperatures and reactions times as indicated in the table. Table 3. Products obtained by the magnesiation of aromatics with (TMP)Mg(Bt>2LiCl and reactions with eletrophiles.

Entry Substate Temp. [⁰C] Time Electrophile Product Yield

52 52a

Preparation of the reagent TMP₂Mg-2LiCl (40a) from TMPMgCl-LiCl

In a dry argon-flushed Schlenk-tube, 2,2,6,6-tetramethylpiperidine (TMPH; 5.07 mL, 30 mmol) was dissolved in THF (30 mL). This solution was cooled to -40°C, and n-BuLi (2.4 M in hexane, 12.5 mL, 30 mmol) was added dropwise. After the addition was complete, the reaction mixture was warmed to 0⁰C and stirred at this temperature for 30 min. Freshly titrated TMPMgCl-LiCl (5b) (1 M in THF, 30 mL, 30 mmol) was then added dropwise to the LiTMP-solution, the reaction mixture was stirred at O⁰C for 30 min, warmed to 25°C and stirred for 1 h. The solvents were then removed in vacuo without heating, affording a yellowish solid. Freshly distilled THF was slowly added under vigorous stirring, until a complete dissolution of the salts was observed. The fresh TMP₂Mg*2LiCl solution was titrated prior to use at O⁰C with benzoic acid using 4-(phenylazo)-diphenylamine as indicator. A concentration of 0.6 M in THF was obtained. Synthesis of 5-chloro-4'-methoxybipheii-2-yl iV,AyV',N'-tetramethyldiamidophosphate

(62c):

In a dry argon-flushed Schlenk-tube the aryl phosphorodiamidate 6Od (2.62 g, 8.00 mmol) was dissolved in THF (8 mL), cooled to -40 ⁰C and TMP₂Mg-2LiCl (0.6 M in THF, 14.7 mL, 8.8 mmol) was added dropwise. The mixture was stirred at -40 °C for 1.5 h. Complete metalation was detected by GC-analysis of reaction aliquots which were quenched with I₂ in dry THF. A solution of ZnCl₂ (1 M in THF, 9,6 mL, 9.6 mmol) was added dropwise, and the resulting mixture stirred for 15 min. A solution of Pd(dba)₂ (88 mg, 2 mol%) and P(2-fur)₃ (72 mg, 4 mol%) in THF (8 mL) was added, followed by 4-iodoanisole (2.06 g, 8.8 mmol) and the reaction mixture was allowed to warm to room temperature. After stirring for 12 h, the reaction mixture was quenched with aq. sat. NH₄Cl solution (20 mL) and extracted with diethyl ether (3 x 50 ml). The combined organic layers were washed with brine, dried over MgSO₄, filtered and concentrated in vacuo. Purification by flash chromatography on silica gel (ethyl acetate) furnished 62c (2.78 g, 90% yield) as an orange oil

Table 4: Products of type 62 and 63 obtained by direct magnesiation of the aromatic phosphoroamidates 60 and 61 with (TMP)₂Mg*2LiCl (2) followed by the reaction with electrophiles (E-X).

Entry Substrate 7I⁰C], Yield

E-X Product t[h] [%r

60a 62d: E=P-C₆H₄OTIPS

2 60a 0, 1 TsCN 62e: E=CN 77^b

3 60a 0, 1 CH₂=C(CH₃)CH₂Br 62f: E=CH₂=C(CH₃)CH₂ 84"

60c 62h: E=P-C₆H₄CO₂Et

75^C

6 60c -40, 4 m-Tol-I 62i: E=m-Tol

7 60c -40, 4 C-C₆H₉Br 62j: 85^b

85^b 6Od 62k: E=COPh

6Od -40, 1.5 ΦuCHO 621: E=^BuC(OH) 19 TI⁰C],

Entry Substrate E-X Product Yield ϊ[h] [%]'

61a 63a: E=Br

12 61a 0, 1 PhCOCl 63b: E=COPh 73^b

13 61a 0, 1 P-IC₆H₄CO₂Et 63c: 78^C

61b 63d

^M Isolated yield of analytically pure product.

^[b] A transmetalation with ZnCl₂ (1.1 equiv) and CuCN*2LiCl (0.5 - 1.3 equiv) was performed.

^M Obtained by a palladium-catalyzed cross-coupling after transmetalation with ZnCl₂ (1.1 equiv).

References and notes:

[1] a) M. Schlosser, Angew. Chem. Int. Ed 2005, 44, 376-393. b) A. Turck, N. PIe, F. Mongin, G. Qύeguiner, Tetrahedron 2001, 57, 4489-4505. c) F. Mongin, G. Qύeguiner, Tetrahedron 2001, 57, 4059-4090 d) M. Schlosser, Eur. J. Org. Chem. 2001, 21, 3975-3984. e) D. M. Hodgson, C. D. Bray, N. D. Kindon, Org. Lett. 2005, 7, 2305-2308. f) J-C. Plaquevent, T. Perrard, D. Cahard, Chem. Eur, J. 2002, S, 3300-3307. g) C. -C. Chang, M. S. Ameerunisha, Coord. Chem. Rev. 1999, 189, 199-278. h) J. Clayden, Organolithiums: Selectivity for Synthesis. Editor(s): J. E. Baldwin, R. M. Williams 2002, Publisher: Elsevier. i) F. Leroux, M. Schlosser, E. Zohar, I. Marek, The preparation of organolithium reagents and intermediates Editor(s): Rappoport, Zvi; Marek, Ilan. Chemistry of Organolithium Compounds 2004, 1, 435-493. Publisher: John Wiley & Sons Ltd. j) K. W. Henderson, W. J. Kerr, Chem.-A Eur. J. 2001, 7(16), 3430-3437. k) K. W. Henderson, W. J. Kerr, J. H. Moir, Tetrahedron 2002, 58(23), 4573-4587. 1) M. C. Whisler, S. MacNeil, V. Snieckus, P. Beak, Angew. Chem, Int. Ed 2004, 43(17), 2206-2225. in) G. Queguiner, F. Marsais, V. Snieckus, J. Epsztajn, Adv. in Het. Chem. 1991, 52, 187-304. n) M. Veith, S. Wieczorek, K. Fries, V. Huch, Z. Anorg. AlIg. Chem. 2000, 626(5), 1237-1245.

[2] a) M-X. Zhang, P. E. Eaton, Angew. Chem. Int. Ed. 2002, 41, 2169-2171. b) Y. Kondo, Y. Akihiro, T. Sakamoto, J. Chem. Soc, Perkin Trans. 1: Org. Bio-Org. Chem. 1996, 19, 2331-2332. c) P. E. Eaton, C. H. Lee, Y. Xiong, J. Am. Chem. Soc. 1989, 111, 8016-18. d) P. E. Eaton, M-X. Zhang, N. Komiya, C-G. Yang, I. Steele, R. Gilardi, Synlett 2003, 9, 1275- 1278. e) P. E. Eaton, R. M. Martin, J. Org. Chem. 1988, 53, 2728-32. f) M. Shilai, Y. Kondo, T. Sakamoto, J. Chem. Soc., Perkin Trans. 1: Org. Bio-Org. Chem. 2001, 4, 442. g) P. Knochel, W. Dohle, N. Gommermann, F. F. Kneϊsel, F. Kopp, T. Korn, I. Sapountzis, V. A. Vu, Angew. Chem. 2003, 115, 4438-4456.

[3] a) Y. Kondo, M. Shilai, M. Uchiyama, T. Sakamoto, /. Am. Chem. Soc. 1999, 121, 3539-3540. b) T. Imahori, M. Uchiyama, T. Sakamoto, Y. Kondo, Chem. Comm. 2001, 23, 2450-2451.

[4] A. Krasovskiy, P. Knochel, Angew. Chem. 2004, 116, 4438; Angew. Chem. Int. Ed. 2004, 43, 3333. b) H. Ren, A. Krasovskiy, P. Knochel, Chem. Commun. 2005, 543. c) H. Ren, A. Krasovskiy, P. Knochel, Org. Lett. 2004, 6_t 4215. [5] /-PrMgCl'LiCI is commercially available from Cliemetall GmbH (Frankfurt)

[6] a) A. J. Clarke, S. McNamara, O. Meth-Cohn, Tetrahedron Lett. 1974, 27, 2373-6. b) Y. G. Gu,; E. K. Bayburt, Tetrahedron Lett. 1996, 37, 2565.

[7] a) H. Froehlich, W. KaIt, /. Org. Chem. 1990, 55, 2993-5. b) C. Peyron, J-M. Navarre, N. Van Craynest, R. Benhida, Tetrahedron Lett. 2005, 46, 3315-3318. c) D. W. Slocum, P. L. Gierer, /. Org. Chem. 1976, 41, 3668-74.

[8] a) Y. G. Gu₁ E. K. Bayburt, Tetrahedron Lett. 1996, 37, 2565-8. b) W. Schlecker, A. Huth, E. Ottow, J. Mulzer, Lieb. Ann. 1995, 8, 1441-6. c) W. Schlecker, A. Huth, E. Ottow, J. Mulzer, /. Org. Chem. 1995, 60, 8414-16. d) A. Bouillon, J-C. Lancelot, V. Collot, P. R. Bovy, S. Rault, Tetrahedron 2002, 58, 3323-3328. e) A. Bouillon, J-C. Lancelot, J. S. de O. Santos, V. Collot, P. R. Bovy, S. Rault, Tetrahedron 2003, 59, 10043-10049. f) A. Bouillon, J-C. Lancelot, V. Collot, P. R. Bovy, S. Rault, Tetrahedron 2002, 58, 4369-4373. g) A. Bouillon, J-C. Lancelot, V. Collot, P. R. Bovy, S. Rault, Tetrahedron 2002, 58, 2885-2890. h) H. Awad, F. Mongin, F. Trecourt, G. Queguiner, F. Marsais, Tetrahedron Lett. 2004, 45, 7873-7877. i) D. L. Comins, M. O. Killpack, J. Org. Chem. 1990, 55, 69-73. j) R. Radinov, Kh, Chanev, M. Khainiova, /. Org. Chem. 1991, 56, 4793-6. k) S. Choppin, P. Gros, Y. Fort, Org. Lett. 2000, 2, 803-805.

[9] (2-Ethyl-hexyl)₂NMgClLiCl is prepared by reacting bis(2-ethylhexyl)amine with J-Pr₂NMgCl LiCl in THF at room temperature for 48h. For a general procedure see A. Krasovskiy, V. Krasovskaya, P. Knochel, Angew. Chem. Int. Ed. 2006, 45, 2958-2961.

Claims

Claims

1. A reagent of the general formula

R¹R²N-Mg-NR³R⁴ ZLiY (II)

wherein

R¹, R², R³, and R⁴ are, independently, selected from H, substituted or unsubstituted aryl or heteroaryl containing one or more heteroatoms, linear, branched or cyclic, substituted or unsubstituted alkyl, alkenyl, alkynyl, or silyl derivatives thereof; and R¹ and R² together, or R³ and R⁴ together can be part of a cyclic or polymeric structure; and wherein at least one of R¹ and R² and at least one of R³ and R⁴ is other than H;

Y is selected from the group consisting of F; Cl; Br; I; CN; SCN; NCO; HaIO_n , wherein n = 3 or 4 and Hal is selected from Cl, Br and I; NO₃; BF₄; PF₆; H; a carboxylate of the general formula R^XCO₂; an alcoholate of the general formula OR^X; a thiolate of the general formula SR^X; R^XP(O)O₂; or SCOR^X; or SCSR^X; O_nSR^x, wherein n = 2 or 3; or NO_n, wherein n = 2 or 3; and a derivative thereof; wherein R^x is a substituted or unsubstituted aryl or heteroaryl containing one or more heteroatoms, linear, branched or cyclic, substituted or unsubstituted alkyl, alkenyl, alkynyl, or derivatives thereof, or H; and z > l;

or as adduct with a solvent.

2. Solution of the reagent according to claim 1 in a solvent.

3. Solution according to claim 2, wherein the solvent is selected from cyclic, linear or branched mono or polyethers, thioethers, amines, phosphines, and derivatives thereof containing one or more additional heteroatoms selected from O, N, S and P, preferably tetrahydrofuran (THF), 2-methyltetrahydrofuran, dibutyl ether, diethyl ether, tert- butylmethyl ether, dimethoxyethane, dioxanes, preferably 1,4-dioxane, triethylamine, ethyldiisopropyl amine, dimethylsulfide, dibutylsulfide; cyclic amides, preferably N- methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), N-butyl-2-pyrrolidone (NBP); cyclic, linear or branched alkanes and/or alkenes wherein one or more hydrogens are replaced by a halogen, preferably dichloromethane, 1,2-dichloroethane, CCI₄; urea derivatives, preferably N,N'-dimethylpropyleneurea (DMPU); aromatic, heteroaromatic or aliphatic hydrocarbons, preferably benzene, toluene, xylene, pyridine, pentane, cyclohexane, hexane, heptane; hexamethylphosphorus triamide (HMPA), CS₂; or combinations thereof.

4. Use of the reagent according to claim 1 in a reaction with an electrophile.

5. Use of the reagent according to claim 1 for the deprotonation of any substrate which can form stabilized or unstabilized carbaniones.

6. Process for the preparation of a mixed Mg/Li amide comprising reacting in a solvent a primary or secondary amine with a Grignard reagent in the presence of a lithium salt, or with a Grignard reagent complexed with a lithium salt, or reacting in a solvent a primary or secondary lithium amide with a magnesium salt.

7. Process for the preparation of a reagent having the general formula

R¹R²N-Mg-NR³R⁴ zLiY (II)

wherein

R¹, R , R³, and R⁴ are, independently, selected from H, substituted or unsubstituted aryl or heteroaryl containing one or more heteroatoms, linear, branched or cyclic, substituted or unsubstituted alkyl, alkenyl, alkynyl, or silicon derivatives thereof; and R¹ and R² together, or R³ and R⁴ together can be part of a cyclic or polymeric structure; and wherein at least one of R¹ and R² and at least one of R³ and R⁴ is other than H;

Y is selected from the group consisting of F; Cl; Br; I; CN; SCN; NCO; HaIO_n , wherein n = 3 or 4 and Hal is selected from Cl, Br and I; NO₃; BF₄; PF₆; H; a carboxylate of the general formula R^XCO₂; an alcoholate of the general formula OR^X; a thiolate of the general formula SR^X; R^XP(O)O₂; or SCOR^X; or SCSR^X; O_nSR^x, wherein n = 2 or 3; or NO_n, wherein n = 2 or 3; and a derivative thereof; wherein R^x is a substituted or unsubstituted aryl or heteroaryl containing one or more heteroatoms, linear, branched or cyclic, substituted or unsubstituted alkyl, alkenyl, alkynyl, or derivatives thereof, or H; and z > 1;

comprising reacting in a solvent R¹R²N-MgX or R¹R²N-MgX-ZLiY with R³R⁴NLi, or reacting

R¹R²NLi and R³R⁴NLi with MgX₂;and

X is defined as Y above.

8. Process according to claim 7, wherein X and Y are independently or both Cl, Br or I, and preferably CL

9. Process according to claim 7 or 8, wherein z is in the range from 1 - 5, preferably from 1.5 - 2.5, more preferably from 1,8 to 2.2, even more preferably from 1.9 to 2.1, still even more preferably from 1.95 to 2.05, and most preferred about 2.

10. Process according to any of the claims 7-9, wherein the Grignard reagent RIVIgX zLiY is /PrMgCl-LiCl.

11. Process according to any of the claims 7-10, wherein the solvent is selected from cyclic, linear or branched mono or polyethers, thioethers, amines, phosphines, and derivatives thereof containing one or more additional heteroatoms selected from O, N, S and P, preferably tetrahydrofuran (THF), 2-methyltetrahydrofuran, dibutyl ether, diethyl ether, tert-butylmethyϊ ether, dimethoxyethane, dioxanes, preferably 1,4-dioxane, triethylamine, ethyldiisopropylamine, dimethylsulfide, dibutylsulfide; cyclic amides, preferably N- methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), N-butyl-2-pyrroIidone (NBP); cyclic, linear or branched alkanes and/or alkenes wherein one or more hydrogens are replaced by a halogen, preferably dichloromethane, 1,2-dichloroethane, CCI₄; urea derivatives, preferably N,N'-dimethylpropyleneurea (DMPU); aromatic, hetero aromatic or aliphatic hydrocarbons, preferably benzene, toluene, xylene, pyridine, pentane, cyclohexane, hexane, heptane; hexamethylphosphorus triamide (HMPA), CS₂; or combinations thereof.