Stereoselective synthesis of 1-methylcarbapenem precursors: Studies on the diastereoselective hydroformylation of 4-vinyl β-lactam with aminophosphonite-phosphinite and aminophosphine-phosphite rhodium(I) complexes

The asymmetric hydroformylation of variously N-substituted 4-vinyl beta-lactams catalyzed by rhodium aminophosphonite- phosphinite and rhodium aminophosphine-phosphite complexes was studied. These products are valuable intermediates in the preparation of 1-methylcarbapenem antibiotics; the stereo selectivity to the desired beta-isomer is related to the presence of a substituent at the N atom of the beta-lactain ring. The regioselectivity (branched/linear) but not the stereoselectivity ( beta/alpha) was found to be dependent on the substrate to catalyst ratio.