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

Reactions of 5-substituted-2-dicyanomethyleneadamantanes (4-Z) with benzylmagnesium bromide (C6H5CH₂MgBr) or alkylmagnësium halides (RMgX) generated the 1,4-addition (5-Z (R)) and/or the hydrogénation (5-Z (H)) products. A variety of substituents X were used: hydro, fluoro, chloro, bromo and phenyl groups. The generation of the different isomeric products from the :u-face or c/;-face by the transfer of the benzyl or alkyl groups, or the hydride from the Grignard reagents is discussed in terms of the electrostatic field influence and the steric hindrance between the Grignard reagents and the substrate 4-Z. Reactions of 4-Br or 4-Ph with phenylmagnesium bromide generated 1,2-addition products 6-Br, 7-Br or 8-Ph when the intermediate A was added to dry methanol or to dilute ice-cold hydrochloric acid solution.