Journal of the Chemical Society Perkin Transactions 1 · 1974 · 67 citations · 0 references
Natural SciencesChemistryMedicinal ChemistryBioorganic ChemistryElectrochemistryOrganic ChemistryCarboxylic AcidsElectrochemical SynthesisOrganic AcidsOrganic SynthesisCathodic Reaction MechanismsCathodic ReductionCathodic SynthesisChemical SubstituentsElectrochemical ReductionElectroorganic SynthesisReaction Mechanism Elucidation
Electrochemical reduction of cephalosporanic acid derivatives (I) bearing various substituents at the 3-position gave the corresponding 3-methylenecepham derivatives (II), a new class of cephalosporins. Reductive opening of the 3-hydroxymethyl-3-cephem-4-carboxylic acid lactone (IV) was effected to give (II) by cathodic reaction. The 3-methylenecepham derivatives (II) were readily isomerized to the 3-methyl-3-cephem derivatives (III) providing a new synthesis of cephalexin [7-(D-2-amino-2-phenylacetamido)-3-methyl-3-cephem-4-carboxylic acid](IIIc). The reaction mechanism is discussed on the basis of deuteriation and polarography of the cephalosporins involved.