A direct route to C-vinylaziridines: Reaction of n-sulfonylimines with allylic ylides under phase-transfer conditions or with preformed ylides at low temperature

Allylic sulfonium salts 3, 5, 7, 11, 12, 13, and arsonium salt 14 react with aromatic, heteroaromatic, and (alpha,beta-unsaturated N-sulfonylimines under solid-liquid phase-transfer conditions in the presence of KOH at room temperature to produce, respectively, vinyl-, (beta>-phenylvinyl)-, and [beta-(trimethylsilyl)vinyl]aziridines in excellent yields within several minutes. In some cases, pyrroline compound 9 is obtained as a minor product. This aziridination reaction has also been carried out with preformed ylides, generated from sulfonium salts 3, 7, arsonium salt 14, and telluronium salts 15, 16 with a base in THF at -78 degrees C. In most examples, quantitative yields were achieved. However, the trans/cis selectivity of the reaction was not high in either case. A semistable allylic sulfonium ylide, i.e., dimethylsulfonium 3-(trimethylsilyl)allylide, was found to not undergo an expected [2,3]-sigma-rearrangement and so can also be used in this reaction.