One-Step Conversion of Aldehydes to Oxazolines and 5,6-Dihydro-4H-1,3-oxazines Using 1,2- and 1,3-Azido Alcohols

The reactions of 1,2- and 1,3-hydroxy azides with aldehydes under acidic conditions were examined. A variety of Lewis acids were examined, of which BF 3 ·OEt 2 was found the most convenient. Trimethylsilyl ether derivatives of the alcohols could also be reacted using trimethylsilyl triflate as the promoter. Twenty-five examples that proceed in moderate to quantitative yields are reported.