WO2011123558A1

WO2011123558A1 - Synthesis of metal complexes

Info

Publication number: WO2011123558A1
Application number: PCT/US2011/030573
Authority: WO
Inventors: Bernard Duane Dombek; Anna E. Cherian
Original assignee: Novomer, Inc.
Priority date: 2010-04-01
Filing date: 2011-03-30
Publication date: 2011-10-06

Abstract

The present disclosure provides novel methods of making aluminum porphyrin carbonyl cobaltate complexes, including methods of reacting a hydrido cobalt carbonyl with an alkyl aluminum porphyrin to generate a carbonyl cobaltate salt of the aluminum porphyrin. Also provided are methods of making hydrido cobalt tetracarbonyl.

Description

SYNTHESIS OF METAL COMPLEXES

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to United States provisional application serial number 61/320,077, filed April 1, 2010, the entirety of which is hereby incorporated herein by reference.

BACKGROUND

[0002] Bimetallic complexes comprising a Lewis acid component and a carbonyl cobaltate are active catalysts for the ring-expanding carbonylation of strained heterocycles, including epoxides, aziridines, and lactones. In particular, such bimetallic complexes comprising an aluminum porphyrin compound as a Lewis-acidic component are particularly useful for the double carbonylation of epoxides to succinic anhydrides (Rowley et al., J. Am. Chem. Soc, 2007, 129, 4948-4960). The synthesis of aluminum porphyrin carbonyl cobaltate complexes typically proceeds by treating a chloroaluminum porphyrin complex with a cobalttetracarbonyl alkali salt. It is Applicant's observation that this procedure is prone to generating unwanted byproducts, particularly in mid- or large-scale syntheses, and there remains a need for methods of making aluminum porphyrin carbonyl cobaltate complexes that are practical and efficient for large-scale use.

SUMMARY OF THE INVENTION

[0003] As described herein, the present invention provides methods for preparing aluminum porphyrin complexes useful as catalysts in a variety of synthetic applications. In certain embodiments, the methods comprise reacting an alkyl aluminum porphyrin with a hydrido cobalt carbonyl to form a carbonyl cobaltate salt of the aluminum porphyrin. In certain embodiments, the present invention provides methods of making a compound of formula I:

wherein each of R¹, R², L, y, and p is as defined herein.

DEFINITIONS

[0004] Definitions of specific functional groups and chemical terms are described in more detail below. For purposes of this invention, the chemical elements are identified in accordance with the Periodic Table of the Elements, CAS version, Handbook of Chemistry and Physics, 75^th Ed., inside cover, and specific functional groups are generally defined as described therein. Additionally, general principles of organic chemistry, as well as specific functional moieties and reactivity, are described in Organic Chemistry, Thomas Sorrell, University Science Books, Sausalito, 1999; Smith and March March 's Advanced Organic Chemistry, 5^th Edition, John Wiley & Sons, Inc., New York, 2001; Larock, Comprehensive Organic Transformations, VCH Publishers, Inc., New York, 1989; Carruthers, Some Modern Methods of Organic

Synthesis, 3^rd Edition, Cambridge University Press, Cambridge, 1987; the entire contents of each of which are incorporated herein by reference. [0005] The terms "halo" and "halogen" as used herein refer to an atom selected from fluorine (fluoro, -F), chlorine (chloro, -CI), bromine (bromo, -Br), and iodine (iodo, -I).

[0006] The term "aliphatic" or "aliphatic group", as used herein, denotes a hydrocarbon moiety that may be straight-chain (i.e., unbranched), branched, or cyclic (including fused, bridging, and spiro-fused polycyclic) and may be completely saturated or may contain one or more units of unsaturation, but which is not aromatic. Unless otherwise specified, aliphatic groups contain 1-30 carbon atoms. In certain embodiments, aliphatic groups contain 1-12 carbon atoms. In certain embodiments, aliphatic groups contain 1-8 carbon atoms. In certain embodiments, aliphatic groups contain 1-6 carbon atoms. In some embodiments, aliphatic groups contain 1-5 carbon atoms, in some embodiments, aliphatic groups contain 1-4 carbon atoms, in yet other embodiments aliphatic groups contain 1-3 carbon atoms, and in yet other embodiments aliphatic groups contain 1-2 carbon atoms. Suitable aliphatic groups include, but are not limited to, linear or branched, alkyl, alkenyl, and alkynyl groups, and hybrids thereof such as (cycloalkyl)alkyl, (cycloalkenyl)alkyl or (cycloalkyl)alkenyl.

[0007] The term "heteroaliphatic" or "heteroaliphatic group", as used herein, denotes an optionally substituted hydrocarbon moiety having, in addition to carbon atoms, from one to five heteroatoms, that may be straight-chain {i.e., unbranched), branched, or cyclic ("heterocyclic") and may be completely saturated or may contain one or more units of unsaturation, but which is not aromatic. The term "heteroatom" refers to nitrogen, oxygen, or sulfur, and includes any oxidized form of nitrogen or sulfur, and any quaternized form of a basic nitrogen. The term "nitrogen" also includes a substituted nitrogen. Unless otherwise specified, heteroaliphatic groups contain 1-6 carbon atoms wherein 1-3 carbon atoms are optionally and independently replaced with heteroatoms selected from oxygen, nitrogen and sulfur. In some embodiments, heteroaliphatic groups contain 1-4 carbon atoms, wherein 1-2 carbon atoms are optionally and independently replaced with heteroatoms selected from oxygen, nitrogen and sulfur. In yet other embodiments, heteroaliphatic groups contain 1-3 carbon atoms, wherein 1 carbon atom is optionally and independently replaced with a heteroatom selected from oxygen, nitrogen and sulfur. Suitable heteroaliphatic groups include, but are not limited to, linear or branched, heteroalkyl, heteroalkenyl, and heteroalkynyl groups. [0008] The term "epoxide", as used herein, refers to a substituted oxirane. Such substituted oxiranes include monosubstituted oxiranes, disubstituted oxiranes, trisubstituted oxiranes, and tetrasubstituted oxiranes. Such epoxides may be further optionally substituted as defined herein. In certain embodiments, epoxides comprise a single oxirane moiety. In certain embodiments, epoxides comprise two or more oxirane moieties.

[0009] The term "unsaturated", as used herein, means that a moiety has one or more double or triple bonds.

[0010] The terms "cycloaliphatic", "carbocycle", or "carbocyclic", used alone or as part of a larger moiety, refer to a saturated or partially unsaturated monocyclic, bicyclic, or polycyclic ring systems, as described herein, having from 3 to 20 members, wherein the aliphatic ring system is optionally substituted as defined above and described herein. Cycloaliphatic groups include, without limitation, cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cycloheptyl, cycloheptenyl, cyclooctyl, cyclooctenyl, bicyclo[2.2.1]heptyl, norbornyl, spiro[4.5]decyl, and cyclooctadienyl. In some embodiments, the cycloalkyl has 3-6 carbons. The terms "cycloaliphatic", "carbocycle" or "carbocyclic" also include aliphatic rings that are fused to one or more aromatic or nonaromatic rings, such as decahydronaphthyl or tetrahydronaphthyl, where the radical or point of attachment is on the aliphatic ring. In some embodiments, a carbocyclic group is bicyclic. In some embodiments, a carbocyclic group is tricyclic. In some embodiments, a carbocyclic group is polycyclic. In certain embodiments, the terms "3- to 14-membered carbocycle" and "C3_i₄ carbocycle" refer to a 3- to 8-membered saturated or partially unsaturated monocyclic carbocyclic ring, or a 7- to 14-membered saturated or partially unsaturated polycyclic carbocyclic ring.

[0011] The term "alkyl," as used herein, refers to saturated, straight- or branched-chain hydrocarbon radicals derived from an aliphatic moiety containing between one and six carbon atoms by removal of a single hydrogen atom. Unless otherwise specified, alkyl groups contain 1-12 carbon atoms. In certain embodiments, alkyl groups contain 1-8 carbon atoms. In certain embodiments, alkyl groups contain 1-6 carbon atoms. In some embodiments, alkyl groups contain 1-5 carbon atoms. In some embodiments, alkyl groups contain 1-4 carbon atoms. In certain embodiments, alkyl groups contain 1-3 carbon atoms. In some embodiments, alkyl groups contain 1-2 carbon atoms. Examples of alkyl radicals include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, iso-butyl, sec-butyl, sec-pentyl, iso-pentyl, tert- butyl, n-pentyl, neopentyl, n-hexyl, sec-hexyl, n-heptyl, n-octyl, n-decyl, n-undecyl, dodecyl, and the like.

[0012] The term "alkenyl," as used herein, denotes a monovalent group derived from a straight- or branched-chain aliphatic moiety having at least one carbon-carbon double bond by the removal of a single hydrogen atom. Unless otherwise specified, alkenyl groups contain 2-12 carbon atoms. In certain embodiments, alkenyl groups contain 2-8 carbon atoms. In certain embodiments, alkenyl groups contain 2-6 carbon atoms. In some embodiments, alkenyl groups contain 2-5 carbon atoms. In some embodiments, alkenyl groups contain 2-4 carbon atoms. In some embodiments, alkenyl groups contain 2-3 carbon atoms. In some embodiments, alkenyl groups contain 2 carbon atoms. Alkenyl groups include, for example, ethenyl, propenyl, butenyl, l-methyl-2-buten-l-yl, and the like.

[0013] The term "alkynyl," as used herein, refers to a monovalent group derived from a straight- or branched-chain aliphatic moiety having at least one carbon-carbon triple bond by the removal of a single hydrogen atom. Unless otherwise specified, alkynyl groups contain 2-12 carbon atoms. In certain embodiments, alkynyl groups contain 2-8 carbon atoms. In certain embodiments, alkynyl groups contain 2-6 carbon atoms. In some embodiments, alkynyl groups contain 2-5 carbon atoms, in some embodiments, alkynyl groups contain 2-4 carbon atoms, in yet other embodiments alkynyl groups contain 2-3 carbon atoms, and in yet other embodiments alkynyl groups contain 2 carbon atoms. Representative alkynyl groups include, but are not limited to, ethynyl, 2-propynyl (propargyl), 1-propynyl, and the like.

[0014] The term "aryl" used alone or as part of a larger moiety as in "aralkyl",

"aralkoxy", or "aryloxyalkyl", refers to monocyclic and polycyclic ring systems having a total of five to 20 ring members, wherein at least one ring in the system is aromatic and wherein each ring in the system contains three to twelve ring members. The term "aryl" may be used interchangeably with the term "aryl ring". In certain embodiments of the present invention, "aryl" refers to an aromatic ring system which includes, but is not limited to, phenyl, biphenyl, naphthyl, anthracyl and the like, which may bear one or more substituents. Also included within the scope of the term aryl", as it is used herein, is a group in which an aromatic ring is fused to one or more additional rings, such as benzofuranyl, indanyl, phthalimidyl, naphthimidyl, phenantriidinyl, or tetrahydronaphthyl, and the like. In certain embodiments, the terms "6- to 10- membered aryl" and "C₆-io aryl" refer to a phenyl or an 8- to 10-membered polycyclic aryl ring. In certain embodiments, the terms "6- to 14-membered aryl" and "C_6-14 aryl" refer to a phenyl or an 8- to 14-membered polycyclic aryl ring.

[0015] The terms "heteroaryl" and "heteroar-", used alone or as part of a larger moiety, e.g., "heteroaralkyl", or "heteroaralkoxy", refer to groups having 5 to 14 ring atoms, preferably 5, 6, or 9 ring atoms; having 6, 10, or 14 π electrons shared in a cyclic array; and having, in addition to carbon atoms, from one to five heteroatoms. The term "heteroatom" refers to nitrogen, oxygen, or sulfur, and includes any oxidized form of nitrogen or sulfur, and any quaternized form of a basic nitrogen. Heteroaryl groups include, without limitation, thienyl, furanyl, pyrrolyl, imidazolyl, pyrazolyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, isothiazolyl, thiadiazolyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolizinyl, purinyl, naphthyridinyl, benzofuranyl and pteridinyl. The terms "heteroaryl" and "heteroar-", as used herein, also include groups in which a heteroaromatic ring is fused to one or more aryl, cycloaliphatic, or heterocyclyl rings, where the radical or point of attachment is on the heteroaromatic ring. Nonlimiting examples include indolyl, isoindolyl, benzothienyl,

benzofuranyl, dibenzofuranyl, indazolyl, benzimidazolyl, benzthiazolyl, quinolyl, isoquinolyl, cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, 4H-quinolizinyl, carbazolyl, acridinyl, phenazinyl, phenothiazinyl, phenoxazinyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, and pyrido[2,3-b]-l,4-oxazin-3(4H)-one. A heteroaryl group may be mono- or bicyclic. The term "heteroaryl" may be used interchangeably with the terms "heteroaryl ring", "heteroaryl group", or "heteroaromatic", any of which terms include rings that are optionally substituted. The term "heteroaralkyl" refers to an alkyl group substituted by a heteroaryl, wherein the alkyl and heteroaryl portions independently are optionally substituted. The term "heteroaralkyl" refers to an alkyl group substituted by a heteroaryl, wherein the alkyl and heteroaryl portions

independently are optionally substituted. In certain embodiments, the term "5- to 10-membered heteroaryl" refers to a 5- to 6-membered heteroaryl ring having 1 to 3 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an 8- to 10-membered bicyclic heteroaryl ring having 1 to 4 heteroatoms independently selected from nitrogen, oxygen, or sulfur. In certain embodiments, the term "5- to 14-membered heteroaryl" refers to a 5- to 6-membered heteroaryl ring having 1 to 3 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an 8- to 14-membered poly eye lie heteroaryl ring having 1 to 4 heteroatoms independently selected from nitrogen, oxygen, or sulfur.

[0016] As used herein, the terms "heterocycle", "heterocyclyl", "heterocyclic radical", and "heterocyclic ring" are used interchangeably and refer to a stable 3- to 7-membered monocyclic or 7- 14-membered bicyclic heterocyclic moiety that is either saturated or partially unsaturated, and having, in addition to carbon atoms, one or more, preferably one to four, heteroatoms, as defined above. When used in reference to a ring atom of a heterocycle, the term "nitrogen" includes a substituted nitrogen. As an example, in a saturated or partially unsaturated ring having 0-3 heteroatoms selected from oxygen, sulfur or nitrogen, the nitrogen may be N (as in 3,4-dihydro-2H-pyrrolyl), NH (as in pyrrolidinyl), or (as in N-substituted pyrrolidinyl). In some embodiments, the term "3- to 7-membered heterocyclic" refers to a 3- to 7-membered saturated or partially unsaturated monocyclic heterocyclic ring having 1 to 2 heteroatoms independently selected from nitrogen, oxygen, or sulfur. In some embodiments, the term "3- to 8-membered heterocycle" refers to a 3- to 8-membered saturated or partially unsaturated monocyclic heterocyclic ring having 1 to 2 heteroatoms independently selected from nitrogen, oxygen, or sulfur. In some embodiments, the term "3- to 12-membered heterocyclic" refers to a 3- to 8-membered saturated or partially unsaturated monocyclic heterocyclic ring having 1 to 2 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or a 7- to 12-membered saturated or partially unsaturated polycyclic heterocyclic ring having 1-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur. In some embodiments, the term "3- to 14-membered heterocycle" refers to a 3- to 8-membered saturated or partially unsaturated monocyclic heterocyclic ring having 1 to 2 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or a 7- to 14-membered saturated or partially unsaturated polycyclic heterocyclic ring having 1-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur.

[0017] A heterocyclic ring can be attached to its pendant group at any heteroatom or carbon atom that results in a stable structure and any of the ring atoms can be optionally substituted. Examples of such saturated or partially unsaturated heterocyclic radicals include, without limitation, tetrahydrofuranyl, tetrahydrothienyl, pyrrolidinyl, pyrrolidonyl, piperidinyl, pyrrolinyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, decahydroquinolinyl, oxazolidinyl, piperazinyl, dioxanyl, dioxolanyl, diazepinyl, oxazepinyl, thiazepinyl, morpholinyl, and quinuclidinyl. The terms "heterocycle", "heterocyclyl", "heterocyclyl ring", "heterocyclic group", "heterocyclic moiety", and "heterocyclic radical", are used interchangeably herein, and also include groups in which a heterocyclyl ring is fused to one or more aryl, heteroaryl, or cycloaliphatic rings, such as indolinyl, 3H-indolyl, chromanyl, phenanthridinyl, or

tetrahydroquinolinyl, where the radical or point of attachment is on the heterocyclyl ring. A heterocyclyl group may be mono- or bicyclic. The term "heterocyclylalkyl" refers to an alkyl group substituted by a heterocyclyl, wherein the alkyl and heterocyclyl portions independently are optionally substituted.

[0018] As used herein, the term "partially unsaturated" refers to a ring moiety that includes at least one double or triple bond. The term "partially unsaturated" is intended to encompass rings having multiple sites of unsaturation, but is not intended to include aryl or heteroaryl moieties, as herein defined.

[0019] As described herein, compounds of the invention may contain "optionally substituted" moieties. In general, the term "substituted", whether preceded by the term

"optionally" or not, means that one or more hydrogens of the designated moiety are replaced with a suitable substituent. Unless otherwise indicated, an "optionally substituted" group may have a suitable substituent at each substitutable position of the group, and when more than one position in any given structure may be substituted with more than one substituent selected from a specified group, the substituent may be either the same or different at every position.

Combinations of substituents envisioned by this invention are preferably those that result in the formation of stable or chemically feasible compounds. The term "stable", as used herein, refers to compounds that are not substantially altered when subjected to conditions to allow for their production, detection, and, in certain embodiments, their recovery, purification, and use for one or more of the purposes disclosed herein.

[0020] In some chemical structures herein, substituents are shown attached to a bond which crosses a bond in a ring of the depicted molecule. It will be appreciated that this indicates that one or more of the substituents may be attached to the ring at any available position (usually in place of a hydrogen atom of the parent structure). In cases where an atom of a ring so substituted has two substitutable positions, two groups may be present on the same ring atom. Unless otherwise indicated, when more than one substituent is present, each is defined independently of the others, and each may have a different structure. In cases where the substituent shown crossing a bond of the ring is -R², this has the same meaning as if the ring were said to be "optionally substituted" as described in the preceding paragraph.

[0021] Suitable monovalent substituents on a substitutable carbon atom of an "optionally substituted" group are independently halogen; -(CH₂)o-4R°; -(CH₂)₀^OR°;

-0-(CH₂)o-₄C(0)OR⁰; -(CH₂)_{0 4}CH(OR°)₂; -(CH₂)_{0 4}SR°; -(CH₂)_{0 4}Ph, which may be substituted with R°;

which may be substituted with R°; -CH=CHPh, which may be substituted with R°; -N0₂; -CN; -N₃; -(CH₂y₄N(R°)₂; -(CH₂)₀^N⁺(R°)₃, - (CH₂)o ₄N(R°)C(0)R°; -N(R°)C(S)R°; -(CH₂)₀_₄N(R^o)C(O)NR°₂; -N(R°)C(S)NR°₂; -(CH₂)₀ ₄N(R°)C(0)OR°; -N(R°)N(R°)C(0)R°; -N(R°)N(R°)C(0)NR°₂; -N(R°)N(R°)C(0)OR°; - (CH₂)o ₄C(0)R°; -C(S)R°; -(CH₂)₀^C(O)OR°; -(CH₂)_{0 4}C(0)N(R°)₂; -(CH₂)₀^C(O)SR°; - (CH₂)o ₄C(0)OSiR°₃; -(CH₂)₀^OC(O)R°; -OC(O)(CH₂)_{0 4}SR- SC(S)SR°; -(CH₂)₀^SC(O)R°; -(CH₂)o ₄C(0)NR°₂; -C(S)NR°₂; -C(S)SR°; -SC(S)SR°, -(CH₂)_{0 4}OC(0)NR°₂; - C(0)N(OR°)R°; -C(0)C(0)R°; -C(0)CH₂C(0)R°; -C(NOR°)R°; -(CH₂)_{0 4}SSR°; -(CH₂)₀ ₄S(0)₂R°; -(CH₂)o^S(0)₂OR°; -(CH₂)₀^OS(O)₂R°; -S(0)₂NR°₂; -(CH₂)_{0 4}S(0)R°; - N(R°)S(0)₂NR°₂; -N(R°)S(0)₂R°; -N(OR°)R°; -C(NH)NR°₂; -P(0)₂R°; -P(0)R°₂; -OP(0)R°₂; -OP(0)(OR°)₂; SiR°₃; -(Ci_₄ straight or branched alkylene)0-N(R°)₂; or -(Ci_₄ straight or branched alkylene)C(0)0-N(R°)₂, wherein each R° may be substituted as defined below and is independently hydrogen, Ci_g aliphatic, -CH₂Ph, -O(CH₂)₀-iPh, or a 5-6-membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or, notwithstanding the definition above, two independent occurrences of R°, taken together with their intervening atom(s), form a 3-12-membered saturated, partially unsaturated, or aryl mono- or polycyclic ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, which may be substituted as defined below.

[0022] Suitable monovalent substituents on R° (or the ring formed by taking two independent occurrences of R° together with their intervening atoms), are independently halogen, -(CH₂)_{0 2}R*, -(haloR*), -(CH₂)_{0 2}OH, -(CH₂)_{0 2}OR*, -(CH₂)_{0 2}CH(OR*)₂;

-O(haloR'), -CN, -N₃, -(CH₂)_{0 2}C(0)R*, -(CH₂)_{0 2}C(0)OH, -(CH₂)_{0 2}C(0)OR*,

-(CH₂)o_₄C(0)N(R°)₂; -(CH₂)₀ 2SR*, -(CH₂)_{0 2}SH, -(CH₂)_{0 2}NH₂, -(CH₂)_{0 2}NHR*, -(CH₂)o-₂NR*2, -NO2, -SiR's, -OSiR's, -C(0)SR* -(Ci_₄ straight or branched

alkylene)C(0)OR*, or -SSR* wherein each R* is unsubstituted or where preceded by "halo" is substituted only with one or more halogens, and is independently selected from Ci_₄ aliphatic, -CH₂Ph, -0(CH₂)o-iPh, or a 5-6-membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur. Suitable divalent substituents on a saturated carbon atom of R° include =0 and =S.

[0023] Suitable divalent substituents on a saturated carbon atom of an "optionally substituted" group include the following: =0, =S, = NR^* ₂, =NNHC(0)R^*, =NNHC(0)OR^*, =NNHS(0)₂R^*, =NR^*, =NOR^*, -0(C(R^* ₂))_{2 3}0- or -S(C(R^* ₂))₂_₃S-, wherein each independent occurrence of R is selected from hydrogen, Ci_6 aliphatic which may be substituted as defined below, or an unsubstituted 5-6-membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur. Suitable divalent substituents that are bound to vicinal substitutable carbons of an "optionally substituted" group include: -0(CR ₂)_{2 3}0-, wherein each independent occurrence of R is selected from hydrogen, Ci_6 aliphatic which may be substituted as defined below, or an unsubstituted 5-6-membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur.

[0024] Suitable substituents on the aliphatic group of R^* include halogen, -R*, -(haloR*),

-OH, -OR*, -O(haloR'), -CN, -C(0)OH, -C(0)OR*, -NH₂, -NHR*, -NR*₂, or -N0₂, wherein each R* is unsubstituted or where preceded by "halo" is substituted only with one or more halogens, and is independently Ci_₄ aliphatic, -CH₂Ph, -O(CH₂)₀ iPh, or a 5-6-membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur.

[0025] Suitable substituents on a substitutable nitrogen of an "optionally substituted" group include -R^†, -NR^† ₂, -C(0)R^†, -C(0)OR^†, -C(0)C(0)R^†, -C(0)CH₂C(0)R^†, -S(0)₂R^†, -S(0)₂NR^† ₂, -C(S)NR^† ₂, -C(NH)NR^† ₂, or -N(R^†)S(0)₂R^†; wherein each R^† is independently hydrogen, Ci_₆ aliphatic which may be substituted as defined below, unsubstituted -OPh, or an unsubstituted 5-6-membered saturated, partially unsaturated, or aryl ring having 0-4

heteroatoms independently selected from nitrogen, oxygen, or sulfur, or, notwithstanding the definition above, two independent occurrences of R^, taken together with their intervening atom(s) form an unsubstituted 3-12-membered saturated, partially unsaturated, or aryl mono- or bicyclic ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur. A substitutable nitrogen may be substituted with three R^† substituents to provide a charged ammonium moiety -N⁺(R^)₃, wherein the ammonium moiety is further complexed with a suitable counterion.

[0026] Suitable substituents on the aliphatic group of R^† are independently halogen, -R*,

-(haloR*), -OH, -OR*, -O(haloR'), -CN, -C(0)OH, -C(0)OR*, -NH₂, -NHR*, -NR*₂, or

-N0₂, wherein each R* is unsubstituted or where preceded by "halo" is substituted only with one or more halogens, and is independently

aliphatic, -CH₂Ph, -O(CH₂)₀-iPh, or a

5-6-membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms

independently selected from nitrogen, oxygen, or sulfur.

[0027] As used herein, the term "catalyst" refers to a substance the presence of which increases the rate and/or extent of a chemical reaction, while not being consumed or undergoing a permanent chemical change itself.

[0028] The term "ligand" refers to molecules, ions, or atoms attached to a central atom of a coordination compound or other complex. In some embodiments, a ligand is a neutral two electron donor molecule of solvent or reagent attached to an aluminum metal center.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 depicts a ReactIR spectrum of the reaction of Co₂(CO)g with H₂/CO at

80 °C. Over the course of the first three hours, the 2072 cm^"1 peak corresponding to Co₂(CO)g disappeared and a peak appeared at 2024 cm^"1 corresponding to HCo(CO)₄. Following the addition of (ClTPP)AlEt in THF, the 2024 cm^"1 peak immediately disappeared, while a peak at 1888 cm^"1 ([Co(CO)₄]^") appeared and increased over several hours.

[0030] Figure 2 depicts the presence of various IR wavenumbers in the same reaction shown in Figure 1. The increase in 1888 cm^"1 and the concomitant decrease in other

wavenumbers correlates with the addition of (ClTPP)AlEt to the reaction. DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

[0031] In certain embodiments, the present invention provides methods comprising reacting an alkyl aluminum porphyrin with a hydrido cobalt carbonyl to form a carbonyl cobaltate salt of the aluminum porphyrin.

[0032] In certain embodiments, the present invention provides methods for preparing a compound of formula I:

I

wherein:

each R¹ and R² is independently hydrogen, halogen, -N0₂, -N₃, -CN, -OR, -SR, -N(R)₂, -C(0)R, -C0₂R, -C(0)C(0)R, -C(0)CH₂C(0)R, -S(0)R, -S(0)₂R, -C(0)N(R)₂, -S0₂N(R)₂, -OC(0)R, -N(R)C(0)R, -N(R)N(R)₂, -N(R)C(0)N(R)₂, -N(R)S0₂N(R)₂, - N(R)S0₂R, -OC(0)N(R)₂, or an optionally substituted moiety selected from the group consisting of: Ci_i₂ aliphatic, Ci_i₂ heteroaliphatic, 3- to 14-membered carbocyclic, 5- to 14-membered heterocyclic, 6- to 14-membered aryl, and 5- to 14-membered heteroaryl, or:

two R² groups or one R¹ and one R² group are taken together with intervening atoms to form an optionally substituted ring selected from the group consisting of 3- to 14- membered carbocyclic, 5- to 14-membered heterocyclic, 6- to 14-membered aryl, and 5- to 14-membered heteroaryl;

L is any ligand capable of coordinating the aluminum metal center;

y is 0, 1, or 2;

each p is independently 0, 1, or 2; and each R is independently an optionally substituted moiety selected from the group consisting of: Ci_i2 aliphatic, C_1-12 heteroaliphatic, 3- to 14-membered carbocyclic, 5- to 14- membered heterocyclic, 6- to 14-membered aryl, and 5- to 14-membered heteroaryl; or: two R groups on the same nitrogen are taken together with intervening atoms to form an optionally substituted 3- to 7-membered saturated, partially unsaturated, or heteroaryl ring having 0-4 additional heteroatoms independently selected from nitrogen, oxygen, or sulfur.

[0033] In some embodiments, p is 0. In some embodiments, p is 1. In some

embodiments, p is 2.

[0034] In certain embodiments, R¹ is hydrogen, halogen, optionally substituted Ci_₆ aliphatic, or optionally substituted 6- to 14-membered aryl. In certain embodiments, each R¹ is hydrogen, optionally substituted Ci_₆ aliphatic, or optionally substituted 6- to 14-membered aryl. In some embodiments, each R¹ is hydrogen. In some embodiments, R¹ is optionally substituted 6- to 14-membered aryl. In some embodiments, R¹ is substituted phenyl. In some embodiments, R¹ is unsubstituted phenyl.

[0035] In some embodiments, R¹ is phenyl substituted with one or more substituents selected from the group consisting of halogen, -N0₂, -CN, Ci_₆ aliphatic optionally substituted with one or more halogens, and -OCi_₆ aliphatic. Exemplary R¹ groups are depicted in Table 1, below.

Table 1. Exemplary R¹ groups

[0036] In certain embodiments, R² is hydrogen, halogen, or optionally substituted Ci_₆ aliphatic. In some embodiments, each R² is hydrogen, halogen, or optionally substituted Ci_₆ aliphatic. In some embodiments, each R² is hydrogen. In some embodiments, R² is optionally substituted Ci_₆ aliphatic. In some embodiments, R² is ethyl. In some embodiments, R² is methyl.

[0037] In certain embodiments, L is a neutral two electron donor. In some embodiments,

L is a solvent molecule. In some embodiments, L is a solvent molecule which is an artifact from the synthesis of a compound of formula I. In some embodiments, L is diethyl ether, t-butyl methyl ether, THF, glyme, or diglyme. In some embodiments, L is acetonitrile, carbon disulfide, or pyridine. In some embodiments, a compound of formula I is synthesized in a solvent which is not a neutral two electron donor and L is absent.

[0038] It will be appreciated that a neutral two electron donor can be coordinatively or covalently bound to the aluminum metal center. In some embodiments, a neutral two electron donor has the function of filling the coordination valence of the aluminum metal center. In certain embodiments, the value of y corresponds to the number of free valence sites on the aluminum metal center. In certain embodiments, y is 2. In certain embodiments, y is 1. In certain embodiments, y is 0.

[0039] In some embodiments, p is 2 and R² is H. In some embodiments, p is 2 and each

R² is independently Ci_₆ alkyl. In some embodiments, /? is 2, one occurrence of R² is methyl and the other is ethyl.

[0040] In certain embodiments, two R² groups are taken together with intervening atoms to form an optionally substituted ring selected from the group consisting of 3- to 14-membered carbocyclic, 5- to 14-membered heterocyclic, 6- to 14-membered aryl, and 5- to 14-membered heteroaryl. In some embodiments, two R² groups are taken together to form an optionally substituted 5- to 6-membered heteroaryl or an optionally substituted phenyl ring.

[0041] Certain compounds of formula I and methods for their preparation are described by Rowley et al., J. Am. Chem. Soc, 2007, 129, 4948-4960 (including supporting information); US Pat. Application No. 12/204,411, and International Patent Application Publication Nos. WO 2004/089923 and WO 2003/050154, each of which is incorporated by reference herein in its entirety. Compounds of formula I are useful as catalysts for carbonylation of epoxides and other heterocycles. The present invention provides methods of making compounds of formula I with decreased or no formation of unwanted byproducts. In certain embodiments, provided methods are amenable to large scale syntheses of compounds of formula I. Without wishing to be bound by any particular theory, it is believed that the disclosed methods are advantageous in their provision of a cobalt tetracarbonyl intermediate (HCo(CO)₄) in situ, whereas known syntheses of compounds of formula I require a separate synthetic step of making NaCo(CO)₄. Not only do the provided methods obviate the need for making and isolating NaCo(CO)₄ as a separate intermediate, the skilled artisan will appreciate that the alkane byproduct generated by the provided methods is easier to separate from the final product than NaCl.

[0042] In certain embodiments, the present invention provides methods of preparing compounds of formula I according to Schemes I and II set forth below. One of ordinary skill in the art will appreciate that a variety of reaction conditions may be employed to promote each of the synthetic transformations as depicted in Schemes I and II, steps S-1 to S-3; therefore, a wide variety of reaction conditions are envisioned (see generally, March 's Advanced Organic

Chemistry: Reactions, Mechanisms, and Structure, M. B. Smith and J. March, 5^th Edition, John Wiley & Sons, 2001 and Comprehensive Organic Transformations, R. C. Larock, 2^nd Edition, John Wiley & Sons, 1999).

[0043] In some embodiments, the synthesis of compounds of formula I includes the reaction set forth in Scheme 1 :

Scheme 1

A C

wherein each of R¹, R², L, y, and p is as defined above and described in classes and subclasses herein, and each R³ is independently a Ci_i₂ alkyl group.

[0044] At step S-1, a porphyrin of formula A is reacted with a trialkylaluminum of formula B to form an alkyl aluminum porphyrin of formula C, thereby generating two equivalents of alkane D. [0045] Certain compounds of formulae A and C and methods for their preparation are described by Adler, A.D. et al., J. Org. Chem., 1967, 32, 476; and Konishi et al., J. Org. Chem., 1990, 55, 816-820, the entire contents of each of which are hereby incorporated by reference.

[0046] In some embodiments, y is 0 or 1 for a compound of formula C.

[0047] One of ordinary skill will realize that while a compound of formula A

encompasses a wide range of combinations of various substituents, such substituents that would be capable of cross reacting with a trialkylaluminum of formula B are less preferred. In certain embodiments, a compound of formula A has no substituents that would react with a

trialkylaluminum of formula B in a way other than depicted in step S-l.

[0048] In certain embodiments, the methods described herein are carried out in a suitable medium. A suitable medium is a solvent or a solvent mixture that, in combination with the combined reacting partners and reagents, facilitates the progress of the reaction therebetween.

[0049] In certain embodiments, step S-l comprises one or more suitable solvents.

Solvents suitable for use in step S-l include aliphatic hydrocarbons (e.g., pentane, hexane, cyclohexane, petroleum ether), halogenated hydrocarbons (e.g., dichloromethane, chloroform, carbon tetrachloride, methyl chloroform, 1 ,2-dichloroethane, 1,1-dichloroethane), aromatic hydrocarbons (e.g., benzene, toluene, xylenes, ethylbenzene), aliphatic ethers (e.g., diethyl ether, t-butyl methyl ether, THF, glyme, diglyme), halogenated aromatic hydrocarbons (e.g., chlorobenzene, dichlorobenzenes), or combinations thereof. In some embodiments, a solvent is an aliphatic halide. In some embodiments, the solvent is dichloromethane, chloroform, or carbon tetrachloride. In some embodiments, the solvent is dichloromethane.

[0050] Suitable temperatures at which the reaction described in step S-l may occur include about -20 °C to about 60 °C. In some embodiments, the temperature is about 0 °C to about 40 °C. In some embodiments, the temperature is about 23 °C. In certain embodiments, the temperature is room temperature.

[0051] In certain embodiments, R³ is methyl. In certain embodiments, R³ is ethyl. In certain embodiments, R³ is n-propyl. In certain embodiments, R³ is isopropyl. In certain embodiments, R³ is n-butyl. In certain embodiments, R³ is isobutyl. [0052] A compound of formula B can be any trialkylaluminum reagent. Several trialkylaluminum reagents are commercially available, and processes for the preparation trialkylaluminum reagents are known in the art, for example as described in US Pat. Nos.

3,006,942 and 3,960,912, the contents of each of which are hereby incorporated by reference. In some embodiments, a trialkylaluminum reagent is trimethylaluminum. In some embodiments, a trialkylaluminum reagent is triethylaluminum. In some embodiments, a trialkylaluminum reagent is tripropylaluminum. In some embodiments, a trialkylaluminum reagent is

triisobutylaluminum. In some embodiments, a trialkylaluminum reagent is trioctylaluminum.

[0053] In certain embodiments, a trialkylaluminum reagent used in step S-l is neat. In certain embodiments, a trialkylaluminum reagent is a highly concentrated solution (e.g., 93% or 97%). In certain embodiments, a trialkylaluminum reagent is a solution in a solvent (e.g., 9%).

[0054] As depicted in Scheme I, compounds of formula A are free base porphyrins. In certain embodiments, a compound of formula A is a tetraphenylporphyrin, wherein each phenyl group is optionally substituted. In some embodiments, a compound of formula A is C1TPP (meso-tetra(4-chlorophenyl)porphyrin). In some embodiments, a compound of formula A is TPP (tetraphenylporphyrin) .

[0055] In certain embodiments, the present invention provides methods comprising the steps of:

a) providing a porphyrin of formula A:

A

wherein each of R¹, R², and p is as defined above and described in classes and subclasses herein; b) reacting the porphyrin of formula A with a trialkylaluminum of formula B:

AI(R³)₃

B

wherein each R³ is independently a C_1-12 alkyl group;

to form an alkyl aluminum porphyrin of formula C:

C

wherein each of L and y is as defined above and described in classes and subclasses herein.

[0056] Scheme 2 depicts a synthesis of compounds of formula I using a compound of formula C.

Scheme 2

I

[0057] At step S-2, dicobaltoctacarbonyl is reacted with hydrogen in the presence of carbon monoxide to form hydrido cobalt tetracarbonyl (HCo(CO)₄). At step S-3, cobalt tetracarbonyl is reacted with an alkyl aluminum porphyrin of formula C to form a compound of formula I and an alkane of formula D.

[0058] In certain embodiments, the source of hydrogen used in step S-2 is syngas or other process gasses containing hydrogen and CO. One of ordinary skill will appreciate that syngas is available and/or can be used with a variety of hydrogen to carbon monoxide ratios (e.g., mole ratio or partial pressure). In embodiments, the ratio of hydrogen to carbon monoxide is about 50:50. In certain embodiments, the ratio of hydrogen to carbon monoxide is about 60:40. In certain embodiments, the ratio of hydrogen to carbon monoxide is about 70:30. In certain embodiments, the ratio of hydrogen to carbon monoxide is about 80:20. In certain embodiments, the ratio of hydrogen to carbon monoxide is about 90: 10. In certain embodiments, the ratio of hydrogen to carbon monoxide is about 40:60. In certain embodiments, the ratio of hydrogen to carbon monoxide is about 30:70. In certain embodiments, the ratio of hydrogen to carbon monoxide is about 20:80. In certain embodiments, the ratio of hydrogen to carbon monoxide is about 10:90.

[0059] Step S-2 is carried out at a pressure suitable for formation of hydrido cobalt tetracarbonyl. In certain embodiments, the pressure is about 100 psi to about 2000 psi. In some embodiments, the pressure is about 200 psi to about 800 psi. In some embodiments, the pressure is about 300 psi to about 700 psi. In some embodiments, the pressure is about 400 psi to about 600 psi. In some embodiments, step S-2 is carried out over a range of pressures. For example, in some embodiments, Co(CO)g and H₂/CO are combined at one pressure prior to heating of the reaction vessel, and then the pressure is increased once temperature has equilibrated.

[0060] Suitable reaction temperature for step S-2 are those that afford formation of hydrido cobalt tetracarbonyl. In certain embodiments, the temperature of step S-2 is about 0 °C to about 150 °C. In certain embodiments, the temperature of step S-2 is about 20 °C to about 100 °C. In certain embodiments, the temperature of step S-2 is about 50 °C to about 90 °C. In certain embodiments, the temperature of step S-2 is about 75 °C to about 85 °C.

[0061] In certain embodiments, step S-2 is carried out in presence of a suitable solvent.

In some embodiments, a solvent for step S-2 is any solvent suitable for hydroformylation. In some embodiments, solvents for use in step S-2 include aliphatic hydrocarbons (e.g., pentane, hexane, cyclohexane, petroleum ether), halogenated hydrocarbons (e.g., dichloromethane, chloroform, carbon tetrachloride, methyl chloroform, 1 ,2-dichloroethane, 1 ,1-dichloroethane), aromatic hydrocarbons (e.g., benzene, toluene, xylenes, ethylbenzene), aliphatic ethers (e.g., diethyl ether, t-butyl methyl ether, THF, glyme, diglyme), halogenated aromatic hydrocarbons (e.g., chlorobenzene, dichlorobenzenes), or combinations thereof. In certain embodiments, the solvent is THF.

[0062] In some embodiments, the present invention provides methods comprising the step of reacting the dicobaltoctacarbonyl with hydrogen in the presence of carbon monoxide to form hydrido cobalt tetracarbonyl.

[0063] At step S-3, hydrido cobalt tetracarbonyl is reacted with an alkyl aluminum porphyrin of formula C to provide a compound of formula I.

[0064] Step S-3 is carried out at a pressure suitable for formation of compound of formula I. In certain embodiments, the pressure is about 50 psi to about 2000 psi. In some embodiments, the pressure is about 200 psi to about 800 psi. In some embodiments, the pressure is about 400 psi to about 700 psi. In some embodiments, the pressure is about 500 psi to about 700 psi. In some embodiments, step S-3 is carried out over a range of pressures. For example, in some embodiments, hydrido cobalt tetracarbonyl and a compound of formula C are combined at one pressure and then the pressure is increased following combination of the reactants.

[0065] Suitable reaction temperature for step S-3 are those that afford formation of compounds of formula I. In certain embodiments, the temperature of step S-3 is about 0 °C to about 150 °C. In certain embodiments, the temperature of step S-3 is about 20 °C to about 100 °C. In certain embodiments, the temperature of step S-3 is about 50 °C to about 90 °C. In certain embodiments, the temperature of step S-3 is about 75 °C to about 85 °C. In some embodiments, hydrido cobalt tetracarbonyl and a compound of formula C are combined at one temperature and then the temperature is increased following combination of the reactants.

[0066] In certain embodiments, the present invention provides methods comprising the steps of: a) providing an alkyl aluminum porphyrin of formula C:

wherein each of R¹, R², R³, L, y, and p is as defined above and described in classes and subclasses herein;

b) providing hydrido cobalt tetracarbonyl; and

c) reacting the alkyl aluminum porphyrin of formula C with hydrido cobalt tetracarbonyl to form a metal complex of formula I:

[0067] In certain embodiments, the present invention provides methods comprising the steps of:

a) providing a porphyrin of formula A:

A

wherein each of R¹, R², and p is as defined above and described in classes and subclasses herein;

b) reacting the porphyrin of formula A with a trialkylaluminum of formula B:

AI(R³)₃

B

wherein each R³ is independently a C_1-12 alkyl group;

to form an alkyl aluminum porphyrin of formula C:

wherein each of L and y is as defined above and described in classes and

subclasses herein;

c) providing hydrido cobalt tetracarbonyl; and

d) reacting the alkyl aluminum porphyrin of formula C with hydrido cobalt tetracarbonyl a metal complex of formula I:

I

[0068] It will be appreciated that certain reagents employed by and/or intermediates or products provided by the present invention are air and/or moisture sensitive. In certain embodiments, one or more of the aforementioned synthetic steps is performed using standard inert handling techniques (e.g., drybox, Schlenk line, etc.).

[0069] In certain embodiments, each of the aforementioned synthetic steps S-l, S-2, and

S-3 is performed sequentially with isolation of each intermediate C and HCo(CO)4 performed after each step. In some embodiments, each of steps S-2 and S-3, as depicted in Scheme 2 above, may be performed in a manner whereby no isolation of intermediate HCo(CO)4 is performed. In certain embodiments, HCo(CO)4 is generated in situ and steps S-2 and S-3 are performed in sequence without any isolation of HCo(CO)4.

[0070] In certain embodiments, all the steps of the aforementioned synthesis may be performed to prepare the desired final product. In some embodiments, two sequential steps may be performed to prepare an intermediate or the desired final product.

EXAMPLES

Experimental Procedures - General Example 1

Preparation of (Cl-TPP)AlEt

[0071] In a 250 mL round bottom flask adapted with a N₂ inlet valve, (C1TPP)H₂ (5.00 g,

6.63 mmol) was dissolved in CH₂C1₂ (100 mL). AlEt₃ solution (1.0 M in hexanes, 6.6 mL, 6.63 mmol) was added dropwise by syringe. The mixture was stirred at room temperature for 3 h. The solvent was removed in vacuo to give a deep green solid.

Example 2

Preparation of [(Cl-TPP)Al][Co(CO)₄]

[0072] In a 300 mL Parr reactor fitted with a React-IR ATR sentinel, Co₂(CO)₈ was added in the glove box. THF (50 mL) was added by syringe under N₂. A mixture of H₂ and CO (50:50, 400 psi) was added to the solution, and the reactor was heated to 80 °C. When the temperature equilibrated, the pressure was increased to 600 psi. The reaction was tracked by IR spectroscopy, following the disappearance of a peak at 2072 cm^"1 (Co₂(CO)g) and the appearance of a peak at 2024 cm^"1 (HCo(CO)₄) as shown in Figure 1. After 3 hours it seemed to reach a steady state. The reactor was cooled to 26 °C and vented to 200 psi. A solution of (Cl-TPP)AlEt (0.0607 g, 0.75 mmol) in THF (50 mL) was added via shot tank to the reactor, and the pressure was increased to 600 psi. The IR peak at 2024 cm^"1 disappeared immediately, while a peak at 1888 cm^"1 ([Co(CO)₄]^") appeared (see Figures 1 and 2). The reaction was heated to 80 C for 16 hours, during which time the peak at 1888 cm^"1 continued to increase. The reactor was cooled, and the solution was transferred to a flask via cannula. The solvent was removed in vacuo to give a purple solid. Example 3

Activity test of new catalyst

[0073] When the catalyst was subjected to standard activity test conditions (0.065 mmol catalyst, 50 niL THF, 6 niL PO (86 mmol) 40 °C, 600 psi CO, 1 hour), PO was carbonylated to BBL at a rate of 549 mol BBL/mol catalyst-hr, as compared with -690 mol BBL/mol catalyst-hr for our standard catalyst.

OTHER EMBODIMENTS

[0074] While we have described a number of embodiments of this invention, it is apparent that our basic examples may be altered to provide other embodiments that utilize the compounds and methods of this invention. Therefore, it will be appreciated that the scope of this invention is to be defined by the appended claims rather than by the specific embodiments that have been represented by way of example.

Claims

What is claimed is:

1. A method comprising reacting an alkyl aluminum porphyrin with a hydrido cobalt carbonyl to form a carbonyl cobaltate salt of the aluminum porphyrin.

2. The method of claim 1, wherein the method comprises steps of:

a) providing hydrido cobalt tetracarbonyl (HCo(CO)₄);

b) providing an alkyl aluminum porphyrin of formula C:

C

wherein:

each R¹ and R² is independently hydrogen, halogen, -N0₂, -N₃, -CN, -OR, -SR, -N(R)₂, -C(0)R, -C0₂R, -C(0)C(0)R, -C(0)CH₂C(0)R, -S(0)R, -S(0)₂R, -C(0)N(R)₂, -S0₂N(R)₂, -OC(0)R, -N(R)C(0)R, -N(R)N(R)₂,

-N(R)C(0)N(R)₂, -N(R)S0₂N(R)₂, -N(R)S0₂R, -OC(0)N(R)₂, or an optionally substituted moiety selected from the group consisting of: Ci_i₂ aliphatic, Ci_i₂ heteroaliphatic, 3- to 14-membered carbocyclic, 5- to 14- membered heterocyclic, 6- to 14-membered aryl, and 5- to 14-membered heteroaryl, or:

two R² groups or one R¹ and one R² group are taken together with intervening atoms to form an optionally substituted ring selected from the group consisting of 3- to 14-membered carbocyclic, 5- to 14-membered heterocyclic, 6- to 14-membered aryl, and 5- to 14-membered heteroaryl; R³ is a Ci_i2 alkyl group;

L is any ligand capable of coordinating the aluminum metal center; y is 0 or 1 ;

each p is independently 0, 1, or 2; and

each R is independently an optionally substituted moiety selected from the group consisting of: C_1-12 aliphatic, C_1-12 heteroaliphatic, 3- to 14-membered carbocyclic, 5- to 14-membered heterocyclic, 6- to 14-membered aryl, and 5- to 14-membered heteroaryl; or:

two R groups on the same nitrogen are taken together with intervening atoms to form an optionally substituted 3- to 7-membered saturated, partially unsaturated, or heteroaryl ring having 0-4 additional heteroatoms independently selected from nitrogen, oxygen, or sulfur;

and

c) reacting the alkyl aluminum porphyrin of formula C with hydrido cobalt tetracarbonyl to form a carbonyl cobaltate salt of the aluminum porphyrin of formula I:

I

wherein y is 0, 1, or 2.

3. The method of claim 1, wherein the step of providing the alkyl aluminum porphyrin of formula C comprises steps of:

a) providing a porphyrin of formula A:

A b) reacting the porphyrin of formula A with a trialkylaluminum of formula B:

AI(R³)₃

B

wherein each R³ is independently a C_1-12 alkyl group;

to form an alkyl aluminum orphyrin of formula C:

C

4. The method of claim 2 or 3, wherein R¹ is hydrogen, halogen, optionally substituted Ci_₆ aliphatic, or optionally substituted 6- to 14-membered aryl.

5. The method of claim 4, wherein each R¹ is hydrogen.

6. The method of claim 4, wherein R¹ is optionally substituted 6- to 14-membered aryl.

7. The method of claim 6, wherein R¹ is phenyl

8. The method of claim 6, wherein R¹ is /?-chlorophenyl.

9. The method of claim 6, wherein R¹ is selected from:

1 1. The method of claim 2 or 3, wherein p is 1.

12. The method of claim 2 or 3, wherein p is 2.

13. The method of claim 2 or 3, wherein R² is hydrogen, halogen, or optionally substituted Ci_6 aliphatic.

14. The method of claim 13, wherein each R² is optionally substituted Ci_₆ alkyl.

15. The method of claim 14, wherein each R² is selected from ethyl or methyl.

16. The method of claim 2 or 3, wherein two R² groups are taken together to form an optionally substituted 5- to 6-membered heteroaryl or an optionally substituted phenyl ring.

17. The method of claim 2 or 3, wherein R³ is methyl.

18. The method of claim 2 or 3, wherein R³ is ethyl.

19. The method of claim 3, wherein the compound of formula A is CITPP (meso-tetra(4- chloropheny l)porphyrin) .

20. The method of claim 3, wherein the compound of formula A is TPP

(tetrapheny lporphyrin) .

The method of claim 2, wherein the compound of formula I is:

25. The method of claim 3, wherein the trialkylaluminum of formula B is triethylaluminum.

26. The method of claim 2, wherein the step of providing hydrido cobalt tetracarbonyl comprises the step of reacting the dicobaltoctacarbonyl with hydrogen in the presence of carbon monoxide to form hydrido cobalt tetracarbonyl.

27. The method of claim 26, wherein the dicobaltoctacarbonyl is reacted with syngas.

28. A method comprising steps of:

a) providing a porphyrin of formula A:

A

wherein:

each R¹ and R² is independently hydrogen, halogen, -N0₂, -N₃, -CN, -OR,

-N(R)₂, -C(0)R, -C0₂R, -C(0)C(0)R, -C(0)CH₂C(0)R, -S(0)R, -S(0)₂R,

-C(0)N(R)₂, -S0₂N(R)₂, -OC(0)R, -N(R)C(0)R, -N(R)N(R)₂,

two R² groups or one R¹ and one R² group are taken together with intervening atoms to form an optionally substituted ring selected from the group consisting of 3- to 14-membered carbocyclic, 5- to 14-membered heterocyclic, 6- to 14-membered aryl, and 5- to 14-membered heteroaryl; each p is independently 0, 1, or 2; and

two R groups on the same nitrogen are taken together with intervening atoms to form an optionally substituted 3- to 7-membered saturated, partially unsaturated, or heteroaryl ring having 0-4 additional heteroatoms independently selected from nitrogen, oxygen, or sulfur; b) reacting the porphyrin of formula A with a trialkylaluminum of formula B:

AI(R³)₃

B

wherein each R³ is independently a C_1-12 alkyl

form an alkyl aluminum orphyrin of formula C:

C

wherein L is any ligand capable of coordinating the aluminum metal center and y is 0 or 1 ;

c) providing hydrido cobalt tetracarbonyl; and

wherein y is 0, 1, or 2.