Tetrasubstituted Pyrrolidines via a Tandem Aza-Payne/Hydroamination Reaction

A facile tandem aza-Payne/hydroamination reaction of aziridinol is reported, which yields highly functionalized pyrrolidines. Addition of alkynyl Grignards to 2,3-aziridinals yields, in most cases, high syn to anti ratios of the aziridinol. Treatment of the syn-aziridinol with base leads initially to an aza-Payne rearrangement, which juxtaposes the amine and the alkyne in favorable orientation to complete the hydroamination. The anti-aziridinol undergoes the aza-Payne rearrangement, but cannot proceed further with the hydroamination.