Chiral ,'-dioxide/Mg(OTf) complex-catalyzed asymmetric [2,3]-rearrangement of generated ammonium salts.

Catalytic enantioselective [2,3]-rearrangements of generated ammonium ylides from glycine pyrazoleamides and allyl bromides were achieved by employing a chiral ,'-dioxide/Mg complex as the catalyst. This protocol provided a facile and efficient synthesis route to a series of -α-amino acid derivatives in good yields with high stereoselectivities. Moreover, a possible catalytic cycle was proposed to illustrate the reaction process and the origin of stereoselectivity.