A process for preparing 3-beta-amino-4-beta-substituted 2-azetidinones and 3-(2,2-dihalogenovinyl)-imino-4-beta-substituted 2-azetidinone and 3-beta-(2,2-dihalogenovinyl)-amino-4-beta-substituted 2-azetidinone intermediates.

摘要

A process for preparing 3β-amino-4β-substituted-2--azetidinones of the formula
wherein R¹ is a group of the formula
wherein R³ and R⁴ are same or different lower alkyls, COB is carboxy or protected carboxy, R² is alkenyloxy, alkynyloxy, alkanoyloxy, or alkylthio; or R¹ and R² taken together represent a group of the formula
wherein Y¹ e.g. is hydrogen, halogen or lower alkoxy, and Y² is alkylidene, which comprises condensing a 3α-amino--4β-substituted-2-azetidinone with a trihalogenoacetaldehyde or the reactive derivative thereof to give a 3α-(2,2,2,-tri- halogenoethylidene)amino-4β-substituted-2-azetidinone, treating the latter with a base to give a novel 3-(2,2-dihalo- genovinyl)amino-4β-substituted-2-azetidinone, reducing the latter with a metal hydride to give a novel 3p-(dihalogenovi- nyl)amino-4β-substituted-2-azetidinone, and hydrolyzing the latter to give the objective compound, which is an inter- . mediate in the preparation of penicillins and cephalosporins.