4-(1,1-Dialkoxycarbonyl-alkyl)azetidin-2-one-derivatives and synthesis of 4-(1-carboxy-alkyl)azetidin-2-one derivatives therefrom

摘要

A 4-(1,1-dialkoxycarbonylalkyl)azetidin-2-one derivative is of the formula:where R¹ and R² each represents alkyl, alkenyl or aralkyl (preferably both are 2-alkenyl), R³ represents CI-4 alkyl, R⁴ represents hydrogen or a hydroxyl-protective group, e.g., tri-substituted silyl, acyl or aralkyl, and R⁵ represents a hydrogen atom or an amino-protective group e.g., tri-substituted silyl, aralkyl or alkoxyalkyl. Synthesis when R⁵ is H is from a malonic acid derivative R^3-COOR^I.COOR² and a 4-acetoxyazetidin-2-one derivative; and when R⁵ is a protective group the thus produced compound is reacted,e.g. with a tri-substituted silyl chloride so as to incorporate such groups.;For synthesis of a 4-(1-carboxyalkyl)azetidin-2-one derivative (II)where R³ represents a CI-4 alkyl and R⁴ represents hydrogen or a hydroxyl-protective group, the compound (I) is de-esterified and decarboxylated (I), and when an amino-protective group is present in (I), this group is then eliminated.;The products (II), especially those having a β-configuration alkyl group, are useful as an intermediate for 1β-alkylcarbapenem-type antibacterials and can thus be produced efficiently on an industrial scale.