Paternó-Büchi reactions of silyl enol ethers and enamides

3-(Silyloxy)oxetanes are obtained by irradiating mixtures of aromatic aldehydes and silyl enol ethers in benzene as the solvent. The reactions occur with high simple diastereoselectivity and, when R1 is chiral, with high facial diastereoselectivity. Under similar conditions, but in acetonitrile rather than benzene as the preferred solvent, the Paternò-Büchi reaction of N-acyl enamines (enamides) gives the corresponding protected 3-aminooxetanes. The cis-products are obtained with significant simple diastereoselectivity.