SYNTHESIS OF 1,2,3-TRISUBSTITUTED AND 1,2,2,3-TETRASUBSTITUTED AZIRIDINES FROM ALPHA-CHLOROKETIMINES

Secondary α-chloroketimines react with lithium aluminium hydride in ether to afford mixtures of cis- and trans-1,2,3-trisubstituted aziridines. The reaction products are formed by nucleophilic addition of hydride across the imino bond and subsequent intramolecular nucleophilic substitution. Tertiary α-chloroketimines react similarly with lithium aluminium hydride to yield 1,2,2,3-tetrasubstituted aziridines. α,α-Dichloroketimines react with lithium aluminium hydride in a stereospecific way to afford cis-aziridines, exclusively. These results are interpreted in terms of formation of an intermediate α-chloroaziridine, from which a chloride anion is expelled to afford an intermediate azirinium chloride. The latter strained intermediate undergoes stereospecific addition of hydride to give cis-aziridines. © 1990.