β-Lactams. 3. Asymmetric Total Syntheis of New Non-Natural 1β-Methylcarbapenems Exhibiting Strong Antimicrobial Activities and Stability against Human Renal Dehydropeptidase-I

Article abstract of DOI:10.1021/jo00041a033

Asymmetric synthesis of 11, the precursor to chiral (3R,4R)-3-<(1R)-1-<(tert-butyldimethylsilyl)oxy>ethyl>-4-acetoxyazetidin-2-one (3) was achieved by utilizing a highly diastereoselective aldol-type reaction of acetaldehyde and the chiral tin(II) enolate of 5.Similar diastereoselective alkylations of chiral and achiral tin(II) enolates 13a-d with chiral 3 were also performed to obtain the desired alkylated azetidin-2-ones (17a-d).Compounds 17a,b were successfully converted to new, non-natural 1β-methylcarbapenems 1a and 1b, which exhibited strong and wide-ranging antimicrobial activities and excellent stability against human renal dehydropeptidase-I.