Ir-catalyzed allylic amination/ring-closing metathesis: A new route to enantioselective synthesis of cyclic β-amino alcohol derivatives

(Chemical Equation Presented) Ir-catalyzed allylic aminations of (E)-4-benzyloxy-2-butenyl methyl carbonate with benzylamine using Feringa's (S_a,S_c,S_c)- phosphoramidite as a chiral ligand afforded linear-aminated achiral product N,O-dibenzyl-4-amino-2-buten-1-ol regioselectively (linear/branched = >99/1), whereas the (E)-5-benzyloxy-2- pentenyl methyl carbonate showed completely opposite regioselectivity (linear/branched = >1/99) and afforded the optically active (3R)-N,O-dibenzylated 3-amino-1-penten-5-ol with very high enantioselectivity (96% ee), which was used as a key intermediate for the effective synthesis of various cyclic β-amino alcohol derivatives through ring-closing metathesis in high yields.