COB(I)ALAMIN AS CATALYST .4. REDUCTION OF ALPHA,BETA-UNSATURATED NITRILES

Cob(I)alamin as Catalyst. 4. Communication. Reduction of α,β‐Unsaturated Nitriles Using catalytic amounts of cob (I)alamin and an excess of metallic zinc as source of electrons 1‐naphthonitril (5) has been reduced to (1‐naphthyl)methylamin (6) and in small amounts to (1‐naphthyl)methanol (7) and (1,2,3,4‐tetrahydro‐1‐naphthyl)methanol (8) (5 ½ h, CH3COOH/H2O; s. Scheme 3). Starting from cyclododecylideneacetonitrile (15) similar conditions (68 h, CH3COOH/H2O) produced the amines 16–19 as well as the nitrogen free saturated aldehyde 20, the corresponding allylic alcohol 21 and the saturated derivative 22 (s. Scheme 6). It is deduced that the first attack of cob (I)alamin on an α,β‐unsaturated nitrile might occur on both the nitrile dipole as well as on the carbon atom in β‐position. Cob (I)alamin in aqueous acetic acid saturates the isolated double bonds in allylic alcohols and amines. In a slow reaction the two different aromatic rings of (1‐naphthyl)methanol (7) have been reduced giving the corresponding tetrahydronaphthalene derivatives 8 and 12, and in one case the production of the octahydroderivative 14 has been observed in a low yield (s. Scheme 5). Copyright © 1979 Verlag GmbH & Co. KGaA, Weinheim