Titanium(III)-Mediated Synthesis of a 1,2,3-Tricarbonyl Moiety from an α-Oximido-β-keto Ester: Application to the Synthesis of the Carbacephem Nucleus

Article abstract of DOI:10.1021/jo00039a009

A general procedure for the conversion of α-oximido-β-keto esters into vivinal tricarbonyl moieties by TiCl3 in aqueous, buffered (pH 5) conditions with acetone cosolvent was demonstrated.As applied to N-hydroxy β-lactam 17, which contained an α-oximido-β-keto ester side chain, these combined reductive and hydrolytic conditions effected simultaneous tricarbonyl formation and β-lactam N-O bond reduction.Vicinal tricarbonyl-containing N-unsubstituted β-lactam 18 was a direct precursor to semifunctionalized carbacephem 1.