Addition reactions to chiral aziridine-2-carboxaldimine toward various enantiopure nitrogen-containing heterocycles

Chiral (2R,1′R)-(1′-phenylethyl)aziridine-2-carboxaldimine was utilized as a nitrogen-containing starting substrate for the preparation of various enantiopure nitrogen-containing heterocycles. The additions of nucleophiles including organomagnesium reagents, cyanotrimethylsilane and ketene acetal to the chiral (2R,1′R)-(1′-phenylethyl)aziridine-2-carboxaldimine proceeded in highly stereoselective manner via chelation controlled transition states. Subsequent treatment of adducts with triphosgene and NaH yielded 5-substituted-4-chloromethylimidazolidin-2-ones. This imine was also served as either aza-diene or aza-dienophile with olefin or diene to provide hetero-Diels–Alder adducts 2-aziridinylpiperidines or 1,2,3,4-tetrahydroquinolines.