Diastereoselective Intermolecular Addition of the 1,3-Dioxolanyl Radical to <i>N</i>-Acyl Aldohydrazones. Asymmetric Synthesis of α-Amino Acid Derivatives

Abstract

[reaction: see text] N-Acyl aldohydrazones I (R = CO(2)Et, alkyl, aryl, and furyl) efficiently trap the 1,3-dioxolanyl radical intermolecularly without external activation at temperatures as low as -78 degrees C. For alkyl aldohydrazones, good diastereoselectivities are obtained in the presence of InCl(3) at low temperature. Elaboration of the adducts (II) allows for the asymmetric synthesis of alpha-amino acid derivatives.