4-(1,1-dialkoxycarbonylalkyl) azetidin-2-one derivative and process for producing 4-(1-carboxyalkyl) azetidin-2-one derivative using the same

摘要

A process for preferentially producing a 4-(1-carboxyalkyl) azetidin-2- one derivative represented by formula (II&bgr;): ##STR1## wherein R.sup. 3 represents a lower alkyl group and R.sup.4 represents a hydrogen atom or a hydroxy-protective group, which involves deesterifying and decarboxylating a 4-(1,1-dialkoxycarbonylalkyl) azetidin-2-one derivative represented by formula (I): ##STR2## wherein R.sup.1 and R.sup. 2 are identical or different and each represents an alkyl group, an alkenyl group, or an aralkyl group, R.sup.3 and R.sup.4 each has the meaning as defined above, and R.sup.5 represents an amino-protective group, and after that, eliminating the amino-protective group from the derivative, where the 4-(1-carboxyalkyl)azetidin-2-one derivative of formula (II&bgr; ) is present in an amount of at least 61% by mol of all 4-(1-carboxyalkyl) azetidin-2-one derivatives produced.