Mechanistic study of the reaction of vitamin B_12s with 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane

Abstract

FARUK NOME and DINO ZANETTE. Can. J. Chem. 58, 2402 (1980). The reaction of vitamin B,,, with 1,l-dichloro-2,2-bis(p-chlorophenyl)ethane results in the formation of trans-4,4'-dichlorostilbene in a two-step process. In the first step, there is a nucleophilic attack by the cobalt(1) at C-1 resulting in the displacement of chloride ion and formation of an alkyl cobalamin with a chlorine atom on the a-carbon. The second step is a cobalt chloride a-elimination which proceeds through a carbenoid type intermediate that readily rearranges to the product.FARUK NOME et DINO ZANETTE. Can. J. Chem. 58, 2402 (1980). La vitamine B,,, rkagit avec le dichloro-1,l bis(p-chlorophCnyl)-2,2 ethane et conduit en deux &tapes a la formation du dichloro-4,4' stilbene trans. La premiere etape est une attaque nucleophile du cobalt(1) au niveau du carbone en position 1 qui provoque le deplacement de I'ion chlorure et conduit a la formation d'une cobalamine alkylke avec un atome de chlore sur la carbone en position a . La seconde &tape consiste en une elimination a de cobalt et de chlore qui se fait via un intermediaire du type carbenoi'de qui se transpose facilement pour donner le produit final.[Traduit par le journal]

Kinetics of the thermolysis of para-substituted benzylcobalamins and derivatives

“…AS a consequence, the formation and cleavage of the Co-C bond of alkylcobalamins and cobinamides in various chemical processes have been topics of continuous interest in the vitamin BIZ chemistry (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Examples are found of homolytic and heterolytic cleavages and it is not always an easy task to decide which is the preferred pathway in many thermal decompositions.…”