Lossen rearrangements under heck reaction conditions

Abstract

The classical Lossen rearrangement converts activated hydroxamic acids to isocyanates that form numerous products upon their reaction with nucleophiles. We report a simple and highly efficient method of using Heck reaction conditions to initiate Lossen rearrangements of hydroxamic acids. In addition, Lossen rearrangements occur in the presence of palladium(II) acetate or triethylamine, components of the Heck reaction, alone. A potential mechanism is provided to explain this reactivity and these results show that Heck reactions and Lossen rearrangements occur under the same conditions and may provide new methods for facile initiation of Lossen rearrangements.