Asymmetric Hydrocyanation of Hydrazones Catalyzed by in Situ Formed O-Silylated BINOL-Phosphate: A Convenient Access to Versatile α-Hydrazino Acids
摘要:
A first organocatalytic enantioselective route was developed for the conversion of readily prepared and air stable aliphatic hydrazones to synthetically valuable alpha-hydrazinonitriles. This BINOL-phosphate catalyzed Strecker-type reaction (see scheme, Ar = p-NO2-Ph) provides a new practical and direct route to alpha-hydrazino acids of synthetic and biological importance. The actually active catalyst is proposed to be an In situ formed O-silylated BINOL-phosphate, thus shifting the nature of catalysis from Bronsted acid to Lewis acid organocatalysis.