Chemo- and regioselective reductive opening of azetidinium ions

Enantiomerically pure azetidinium trifluoromethanesulfonates were opened by various hydride reagents. LiAlH4 and NaBH3CN reacted with a complete regioselectivity and the latter reagent also reacted in a chemoselective way, leaving unaffected an ester or a cyano moiety present in the substrate. This reaction provides 1,2-diamines, 1,2- and 1,4-amino alcohols or α-amino esters by combining proper choice of substrate and hydride reagent.