Cob(I)alamin Differentiating Alkenes During Saturation

Article abstract of DOI:10.1002/hlca.19840670306

The olefins 2, 7, 11, and 19 have been reduced using catalytic amounts of cob(I)alamin(1(I)).During a slow saturation, the catalyst is able to differentiate the two diastereotopic faces of the endocyclic double bonds in 11 (t_1/2 40 d) and 19 (t_1/2 80 d, cf.Scheme 4).The substrates 2 (t_1/2 1 h, cf.Scheme 2) and 7 (t_1/2 4 h, cf.Scheme 3) are reduced much faster.A rationalization of the data can be obtained formulating tertiary alkylcobalamins as intermediates.Of the oxime 6 ( cf.Scheme 2) and the p-bromobenzoate 23 (cf.Scheme 5) the structures have been determined by X-ray analysis.