[1,3] Sigmatropic rearrangement of ketene silyl acetals derived from benzyl α-substituted propanoates

A novel [1,3] sigmatropic rearrangement of ketene silyl acetals derived from benzyl α-substituted propanoates is developed. The reaction of ketene silyl acetal derived from optically active 1-phenylethyl 2-methylpropanoate mainly proceeds with the retention of chirality at the benzyl position to give the corresponding optically active silyl ester under thermodynamic conditions.