Face selectivity in the reactions of Grignard reagents with 5-substituted-2-dicyanomethyleneadamantanes

Reactions of 5-substituted-2-dicyanomethyleneadamantanes (4-Z) with benzylm agnesium bromide (C6H5CH2MgBr) or alkylmagnesium halides (RMgX) generated t he 1,4-addition (5-Z (R)) and/or the hydrogenation (5-Z (H)) products. A va riety of substituents X were used: hydro, fluoro, chloro, bromo and phenyl groups. The generation of the different isomeric products from the zu-face or en-face by the transfer of the benzyl or alkyl groups, or the hydride fr om the Grignard reagents is discussed in terms of the electrostatic field i nfluence and the steric hindrance between the Grignard reagents and the sub strate 4-Z. Reactions of 4-Br or 4-Ph with phenylmagnesium bromide generate d 1,2-addition products 6-Br, 7-Br or 8-Ph when the intermediate A was adde d to dry methanol or to dilute ice-cold hydrochloric acid solution.