“…4 While the lipase-catalyzed hydrolysis of cis-3-acetyloxy-4-t-butyl-2-azetidinone gives enantiopure 3R-cis-3-acetyloxy-4-t-butyl-2-azetidinone in a good yield, 5 biocatalytic reductions of a-keto-b-lactams with yeast reductases produce ahydroxy-b-lactams with re-and si-face selectivity. 6 Recently, the N-heterocyclic carbene catalyzed asymmetric Staudinger reaction has provided another attractive approach to the preparation of chiral b-lactam derivatives. 7 Because of the paramount importance of b-lactams in chemistry, biology and medicine, it is highly desirable to establish general and efficient methods for the synthesis of diverse b-lactam compounds of excellent enantiopurity.…”