Highly Regioselective Transformation of Alkenyl Bromides into α-Bromoaziridines and α-Bromohydrazones

[reaction: see text] The synthetic utility of alpha-halohydrazones is an underexplored area due to the lack of chemo- and regioselective routes towards these molecules. Herein, we describe a general method for alpha-bromohydrazone synthesis via the rearrangement of alpha-bromoaziridines, which can be readily prepared for the first time from the corresponding alkenyl bromides. The rearrangement of alpha-bromoaziridines into alpha-bromohydrazones proceeds with high yields and with high selectivities.