| 摘要 |
PURPOSE:The reaction between a Schiff base and a ketene in the presence of stannous alcoholate or stannous thiolate gives the objective compound which is used as a synthetic intermediate of beta-lactam antibiotics in high yield under mild conditions. CONSTITUTION:The objective compound is obtained by reaction of a Schiff base with a ketene in the presence of a stannous alcoholate or stannous thiolate, when needed, a Lewis acid such as stannous chloride in a solvent such as THF at -100-23 deg.C. EFFECT:A Schiff base derived from an aliphtatic aldehyde also gives a corresponding beta-hydroxy(thio)ester. The process according to the present invention, enables the dominant formation of one diastereomer regarding to the alpha,beta-relative configuration.
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