AN IMPROVED PREPARATION OF ENAMINES OF ACYLSILANES, A NEW SYNTHESIS OF ACYLSILANES

The use as solvent of hexamethylphosphortriamide instead of the previously used tetrahydrofuran has allowed the synthesis in high yield of enamines of acylsilanes (2) from cyanohydrins (1) by reductive silylation with Me3SiCl/Li. Protodesilylation of 2a (R = R′ = Me) by HCl gas in dry diethyl ether or by trimethylchlorosilane in methanol gave, after neutralization, a quantitative yield of the enamine Me2C=C(SiMe3)NH2, which was surprisingly stable. Its ready hydrolysis to the corresponding acylsilane provided a new route to this type of compound. Reaction of bromine with 2a gave α-bromoisobutyronitrile. © 1990.