Unexpected alkoxyl migration in the reaction of silyl ketene acetals with p-toluenesulfonyl azide

The reaction of p-toluenesulfonyl azides with several silyl ketene acetals has been investigated, 1-Trimethyl silyloxy-ethylene reacted with TsN3 to g ive a good yield of N-p-toluenesulfonyl substituted glycinates exclusively. However, during the reaction of 1-trimethylsilyroxy-propene with TsN3, an unexpected alkoxyl migration occurred to give N-acylsulfonyl amides; other products, N-p-toluenesulfonyl substituted aziridines were also obtained. In the case of dialkyl substituted silyl ketene acetals, three products were formed, i.e. aziridines, alpha -amino esters, and N-acylsulfonyl amides. Th e mechanism for the alkoxyl migration was discussed. (C) 2001 Elsevier Scie nce Ltd. All rights reserved.