Efficient and Practical Synthesis of a Potent Anti-MRSA β-Methylcarbapenem Containing a Releasable Side Chain

We describe a convergent synthesis of the MRSA β-methyl carbapenem 1, wherein the molecule is assembled from the naphthosultam side chain 2 and the allylic carbonate of the β-Me carbapenem piece 6 . The β-Me stereochemistry of 6 is set up in a novel titanium enolate addition into the TBDMS acetoxy azetidinone 5 . The benzenesulfonate salt of 1 is endowed with exceptional stability.