cis-2-Alkoxy-3-aminooxolanes 4 weresynthesized in a remarkably stereospecific manner byalcoholysis of α-chloro-γ-((trimethylsilyl)oxy)ketimines2, obtained by alkylation of α-chloroketimines 1 with 2-bromo-1-((trimethylsilyl)oxy)ethane.The stereospecificity of the cyclization waslost when the alcoholysis was performed in the presence of base.However, complete transformationof the mixtures of cis- andtrans-2-alkoxy-3-aminooxolanes into the more stablecis-compounds wasachieved with hydrogen chloride in methanol. A mechanisticrationale for these stereochemicalaspects is presented.