Regioselective Addition of Trimethylsilyl Cyanide to β-Alkoxyvinyl Alkyl Ketones

The 1,2- and 1.4-addition reactions of trimethylsilyl cyanide to alkyl vinyl ketones were studied. Regioselectivity of this reaction depends on the structure of alkyl vinyl ketones, the reaction temperature and the nature of catalyst. The presence of alkoxy group in β-position of α,β-enone is the important condition for realization of 1,4-addition. Ambient temperature (25°C) or base catalyst (NEt3) directed the reaction predominantly into 1,2-addition; higher temperature, electrophilic catalyst (I2) and bulky alkyl substituents near the carbonyl group directed the reaction in 1,4-addition route. Hydrolysis of 1,4-adducts yields saturated fluorine-containing ketones containing CN- and ethoxy groups at the β-position.