[3 + 2]-Annulations of N-Hydroxy Allenylamines with Nitrosoarenes: One-Pot Synthesis of Substituted Indole Products.

In the presence of O2 and an IPrCuCl additive (5 mol %), [3 + 2]-annulation reactions of N-hydroxyaniline with nitrosobenzenes in cold toluene form isoxazolidin-5-ol derivatives. Heating the same reaction mixture with DBU in toluene affords highly functionalized indole products efficiently. This method provides short synthesis of several bioactive molecules including WIN 48098, WIN 53365, and JWH 015.