STEREOSPECIFIC SYNTHESIS OF CIS-2-ALKOXY-3-AMINOOXOLANES

cis-2-Alkoxy-3-aminooxolanes 4 were synthesized in a remarkably stereo specific manner by alcoholysis of alpha-chloro-gamma-((trimethylsilyl) oxy)ketimines 2, obtained by alkylation of alpha-chloroketimines 1 wit h 2-bromo-1-((trimethylsilyl)oxy)ethane. The stereospecificity of the cyclization was lost when the alcoholysis was performed in the presenc e of base. However, complete transformation of the mixtures of cis- an d trans-2-alkoxy-3-aminooxolanes into the more stable cis-compounds wa s achieved with hydrogen chloride in methanol. A mechanistic rationale for these stereochemical aspects is presented.