2-Azetidinone → HCID 70606043, compound

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Reaction Steps

The azetidin-2-ones provided by this invention are useful as intermediates in the preparation of 3-hyroxy cephalosporin antibiotics. In particular, a 1-(1-protectedcarboxy-2-hydroxy-3-bromo-1-propenyl)-3-amido(or imido)-4-formylthio-azetidin-2-one of this invention can readily be cyclized to provide the corresponding 7-amido (or imido)-4-protected-carboxy-3-hydroxy-3-cephem. Such cyclization of the azetidinone is effected by reaction with a cyclizing agent, such as for example 1,5-diazobicyclo[5.4.0]undec-5-ene (DBU) or mercuric acetate. As an example, 1-(1-tert.-butyloxycarbonyl-2-hydroxy-3-bromo-1-propenyl)-3-phenoxyacetamido-4-formylthio-azetidin-2-one can be treated with DBU in a suitable solvent, for instance dichloromethane, thereby effecting a cyclization of the azetidinone to provide tert.-butyl 7-phenoxyacetamido- 3-hydroxy-3-cephem-4-carboxylate.

Provenance & Evidence