4749-12-6

Upstream product

• 107987-07-5 ethyl 2-(bromomethyl)-2-methyl-3-oxobutanoate 
• 112818-16-3 methyl 2-(iodomethyl)-2-methyl-3-oxobutanoate 
• 108349-21-9 ethyl 2-acetyl-2-iodomethylpropionate 
• 6111-99-5 ethyl diazoalaninate 

Relevant academic research and scientific papers

Development of metal-organic framework (MOF)-B12 system as new bio-inspired heterogeneous catalyst

Abstract A novel bimetal complex {Zn4Ru2(bpdc)4·4C2NH8·9DMF}n (1) (H2bpdc = 4,4′-biphenyldicarboxylic acid) was synthesized by the solvothermal method. The results of the X-ray crystallographic analysis revealed that 1 crystallizes in the orthorhombic Pna21 space group, which has a 3D 2-fold interpenetrated hex framework, with open channel sizes along the [010] direction of ca. 1.4 nm × 1.4 nm. The photosensitizer [Ru(bpy)3]2+ was adsorbed into the 1 to form Ru@MOF by cation exchanging. A cobalamin derivative (B12), heptamethyl cobyrinate, was also effectively immobilized on Ru@MOF, and the resulting hybrid complex, B12-Ru@MOF, exhibited a high reactivity for the dechlorination reaction of 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) under an N2 atmosphere by visible light irradiation in the solid state. The catalysis of B12-Ru@MOF can still reach more than a ca. 80% conversion after third recyclings. Furthermore, the heterogeneous catalyst, B12-Ru@MOF, was useful for the cobalamin-dependent reaction, such as the 1,2-migration of the acetyl group.

The reactions of diazo compounds with lactones. Part 1. Cyclopropanespiro-β-lactones from diketene: Synthesis and reactions

The cyclopropanespiro-β-lactones 3, 4 and 12 can be prepared by the metal catalysed, or photochemically promoted decomposition reactions of diazocompounds in the presence of diketene. The thermal reactions of these compounds give a variety of products depending on the nature of the spirolactone; these include a furan 9a, 1,4-dicarbonyl compounds 18a-c and 19b, a pyranone 20b, furanones 21a, 21f and 22a and the enol 16. The boron trifluoride promoted reaction of a mixture of 3b and 4b gives a 13-ketoacid. Mechanisms are proposed for the formation of these products. The rearrangment of the cyclopropanespiro-β-lactones to furan-2(5H)-ones and furan-2-(3H)-ones 6-8, 21a, 21f, 22a and 24 is shown to be a general reaction that involves metal catalysis. A mechanism based on formation of a metallocycle by a novel insertion of the metal into the C-O bond of the β-lactone ring is proposed for this rearrangement. This accounts for the observed features of the reaction.

REACTIONS RELATED TO COENZYME B12 DEPENDENT REARRANGEMENTS: METAL MEDIATED FREE RADICAL ACYL MIGRATIONS IN METHYL AND CYCLOPROPYL SUBSTITUTED MODELS

Free radicals generated from the methylmalonylcoenzyme A mutase model substrates (3) and (4) by chromium(II) reduction, or by pyrolysis of the analogous cobaloximes, underwent -migration only in the acyl series (R=Ph, Me) and not the critical ester series (R=OEt, SBu).The mechanism of the migration was implied by incorporation into (4) of the cyclopropyl ring, the opening of which demonstrated the free radical nature of rearranged intermediate.

Electrochemical Carbon-skeleton Rearrangements catalysed by Hydrophobic Vitamin B12 immobilised in a Polymer-coated Electrode

A glassy carbon electrode was coated with a polymer species derived from a hydrophobic vitamin B12 and Araldite CT-200, and the immobilised cobalt complex catalysed the electrochemical carbon-skeleton rearrangements of alkyl halides having electron-withdrawing groups.

Redox Behavior of Simple Vitamin B12 Model Complexes and Electrochemical Catalysis of Carbon-Skeleton Rearrangements

Various cobalt complexes of 4,10-dipropyl-5,9-diazatrideca-4,9-diene-3,10-dione dioxime, (C2C3)(DOH)2pn, were prepared, and redox behavior of them was investigated by means of cyclic voltammetry; Co(II)/Co(I) redox potentials in the range of -0.69 through -0.7 V vs.Ag/AgCl.The monomethylated complex, which has a cobalt-carbon bond at one axial site of the nuclear cobalt, was disproportionated to the dimethylated complex, involving two cobalt-carbon bonds at both axial sites, and the CoI species by one-electron reduction.The dimethylated complex was inactive for electrochemical reduction, but transformed into the monomethylated complex via cleavage of a cobalt-carbon bond upon electrochemical oxidation.The electrolyses of 1-bromo-2,2-bis(ethoxycarbonyl)propane, 1-bromo-2-cyano-2-ethoxycarbonylpropane, and 2-acetyl-1-bromo-2-ethoxycarbonylpropane in the presence of IIIBr2> in N,N-dimethylformamide did not proceed in a divided cell at -2.0 vs.Ag/AgCl, since the corresponding dialkylated complexes, inactive for electrochemical reduction, were formed in the course of reaction.When imidazole was added to solutions for the electrolysis, the reaction proceeded efficiently by the trans effect arising from the coordinated axial base and the corresponding carbon-skeleton rearrangement products were obtained.On the other hand, the carbon-skeleton rearrangement proceeded in an undivided cell even in the absence of imidazole; the dialkylated complex was decomposed to give the monoalkylated complex and the reduction and rearrangement products by electrochemical ocxidation on the anode.

Redox Behavior of Simple Vitamin B12 Model Complexes with Cobalt-Carbon Bonds and Catalytic Carbon-Skeleton Rearrangements

The cobalt complex of 2,10-diethyl-3,9-dipropyl-1,4,8,11-tetraaazaundeca-1,3,8,10-tetraene-1,11-diol catalyzed electrolyses of alkyl halides with electron-withdrawing groups at the β-position to afford rearrangement products via oxidation of the corresponding dialkylated complexes as intermediates.

Hydrophobic Vitamin B12. Part 6. Carbon-skeleton Rearrangement via Formation of Host-Guest Complexes derived from an 'Octopus Azaparacyclophane and hydrophobic Vitamin B12 Derivatives: a Novel Holoenzyme Model System

The alkylation reactions of a hydrophobic vitamin B12 derivative with alkyl bromides in an 'octopus' azaparacyclophane having eight hydrocarbon chains have been investigated.Molecular discrimination has been shown to originate from electrostatic interaction between the octopus cyclophane and the alkyl bromides.Alkylation was enhanced by desolvation and proximity effects operating on the reacting species via formation of a ternary complex composed of the octopus cyclophane, the hydrophobic vitamin B12 derivative, and an alkyl halide.Carbon-skeleton rearrangement reactions of alkyl ligands bound to the hydrophobic vitamin B12 were found to be markedly favoured in the hydrophobic cavity provided by the octopus cyclophane, relative to the reactions in methanol and benzene, under anaerobic photolysis conditions at ordinary temperatures.The same reactions took place readily in solid benzene below 4 deg C under similar conditions.The central cobalt atom of the hydrophobic vitamin B12 participates in the rearrangement reaction via formation of a tight pair with an alkyl radical species.Non-enzymic rearrangement reactions have been shown here to proceed quite efficiently by employing a relevant apoenzyme model.

1,2-Migrations in Free Radicals Related to Coenzyme B12 Dependent Rearrangements

The free radicals XC(CH3)(COOR)CH2., where X=C(=O)Me (1), C(=O)SEt (2), C(=O)OEt (3), C(=CH2)Me (4), and C6H5 (5), were generated by reaction of the corresponding bromides with (n-Bu)3SnH.The rates of rearrangement involving 1,2-migration of X (to form .C(CH3)(COOR)(CH2X)) were measured in competition with trapping by (n-Bu)3SnH.The measurements yielded the following rearrangement rate constants, kr, and activation parameters, ΔH+ and ΔS+: (1) 1.2E4 s-1 at 45 deg C, 11.0 kcal/mol, -4 cal/mol.K; (2) 23.5 s-1 at 60.5 deg C, 13.8 kcal/mol, -11 cal/mol.K; (3) -1 at 113 deg C; (4) 3.0E5 s-1 at 45 deg C, 10.0 kcal/mol, -2 cal/mol.K; (5) 5.0E3 s-1 at 61 deg C.From the results of crossover experiments it is concluded that the rearrangements of 1 and 2 are intramolecular processes, probably proceeding through cyclopropyloxy radical intermediates or transition states.The carbanions corresponding to 1-5 (i.e., XC(CH3)(COOR)CH2-, generated by reduction of the corresponding bromides with sodium naphthalene) also rearrange rapidly but, in each case, with some contribution from migration of the ester group.This represents the first demonstration of spontaneous 1,2-migration of a thioester group in a free radical and models the coenzyme B12 dependent methylmalonyl-CoA mutase rearrangement.The results support a free-radical rearrangement mechanism for the latter reaction.

Hydrophobic Vitamin B12. V. Electrochemical Carbon-Skeleton Rearrangement as Catalyzed by Hydrophobic Vitamin B12: Reaction Mechanisms and Migratory Aptitude of Functional Groups

The carbon-skeleton rearrangements as catalyzed by heptamethyl cobyrinate perchlorate, 1ester>ClO4, were investigated under electrochemical conditions.The controlled-potential electrolysis of 2,2-bis(ethoxycarbonyl)-1-bromopropane, which is considered to be a model substrate for methylmalonyl-CoA mutase, was catalyzed by 1ester>ClO4 in N,N-dimethylformamide to give the rearrangement product, 1,2-bis(ethoxycarbonyl)propane, as a major one at -1.5 V vs.SCE in the presence of acetic acid and at potentials more cathodic than -1.8 V vs.SCE without acetic acid in the dark.The electrochemical carbon-skeleton rearrangement was postulated to proceed via formation of anionic intermediates.The electrolyses of 1-bromo-2-cyano-2-ethoxycarbonylpropane, 2-acetyl-1-bromo-2-ethoxycarbonylpropane, and 1-bromo-2-propane with 1ester>ClO4 also afforded the corresponding carbon-skeleton rearrangement products.The results indicated that substrates with two electron-withdrawing groups placed on the β-carbon atom with combination of one carboxylic ester and one of carboxylic ester, acetyl, and cyano moieties readily gave the corresponding rearrangement products which were derived from individual migration of the substituent groups.Substrates with only one of the electron-withdrawing groups, carboxylic ester, acetyl, and cyano, did not give any rearrangement product, but a substrate with one thioester group afforded the corresponding rearrangement product.The migratory aptitude of electron-withdrawing groups was found to decrease in the order: COSR>COR>COOR>CN.Both electronic character and steric bulkiness of the migrating groups are apparently reflected on this tendency, even though relative contributions of these effects are much dependent on the nature of β-substituents.

Reactions Potentially Related to Coenzyme B12 Dependent Rearrangements: Observations on the Radical -Acyl and -Thiol Ester Migrations

Reaction of 2-iodomethyl-2-methyl-3-oxo esters with tributyltin radicals, generated photochemically from hexabutylditin or tributyltin hydride in cyclohexane, or benzene-acetonitrile, resulted in a -acyl migration in 10-63percent yields dependent on the source of tin radical and substrate used.Radical migration was confirmed by the use of tributyltin deuteride.Thiol ester group migration was not observed.A new, highly efficient method for thiol ester synthesis is described.