PALLADIUM(II)-ASSISTED DIFUNCTIONALIZATION OF MONOOLEFINS - TOTAL SYNTHESIS OF (+)-NEGAMYCIN AND (-)-5-EPI-NEGAMYCIN

(+)-Negamycin and (-)-5-epi-negamycin were synthesized by a process involving the palladium-(II)-assisted alkylation of an optically active ene carbamate followed by carbonylative coupling to a trialkylvinyltin. The synthesis of (+)-negamycin was completed in 15 steps with an overall yield of 13%. The synthesis of (-)-5-epi-negamycin was completed in 12 steps with an overall yield of 20%. In preparing these compounds, a highly diastereoselective reduction of an unsaturated ketone and an efficient intramolecular Mitsunobu reaction were also carried out.