Cyanation of nucleophilic alkynes:: easy approach to element-substituted α-cyanoenamines

The reactions of trimethylsilyl cyanide and tributyltin cyanide with ynamines proceeds as a regioselective syn-addition and provide previously unknown beta -elementosubstituted alpha -cyanoenamines as pure E-isomers. The reaction of cyanogen bromide with ynamines as well the hydrocyanation of phosphorus substituted N,N-diethylaminoacetylenes by acetone cyanohydrin also proceeds as regioselective syn-addition, though the initially formed Z-isomers undergo an easy transformation into E-isomers. Cross-coupling reaction of beta -bromo-otcyanocnamine with arylboronic acids were shown to be an easy and convenient approach to alpha -dialkylaminosubstituted cynnamonitriles. (C) 2001 Elsevier Science Ltd. All fights reserved.