An efficient asymmetric synthesis of the mercaptopyrrolidine side chain of an important β-methyl carbapenem antibiotic

Abstract An efficient asymmetric synthesis of the mercaptopyrrolidine side chain 2 1s described. The β-ketoester 4 is hydrogenated diastereoselectively to give the (R)-β-hydroxyester 5 . The remaining functional groups are installed via a thiol Mitsunobu reaction and a reduction of a secondary amide to produce 2 in 34% overall yield from BOC-L-trans-4-hydroxyproline methylester 3 (Scheme 1).