Aminals as substrates for sulfur ylides: a synthesis of functionalized aziridines and N-heterocycles

Sulfur ylides stabilized by Ar, vinyl, or amide groups react with five-membered-ring tert-butylsulfinyl aminals to give functionalized chiral, nonracemic aziridines in high yield and with good selectivities (up to 15:1 trans:cis, up to >95:5 trans dr, always >95:5 cis dr). The intermediate aziridines can be converted into pyrrolidines or piperidines depending on the reaction conditions.