| 摘要 |
PROBLEM TO BE SOLVED: To obtain in a simple operation in high yield the subject compound useful as an intermediate for various cephalosporin-based antibiotics by continuously carrying out deacylation and chlorination during the deacylation process without isolation and purification of the products in the respective reactions. SOLUTION: An azetidinone derivative of formula I [R<1> is a (substituted)aryl, arylmethyl or aryloxymethyl; R<2> is a carboxyl-protective group; R<3> is a (substituted)aryl] is reacted with phosphorus pentachloride in an organic solvent in the presence of a hydrogen chloride scavenger to form an iminochloride form, which is then reacted with a chlorinating agent to form a chloroimino chloride form of formula III, which is, in turn, reacted with an alcohol to form a chloroiminoether form of formula IV (R<4> is an alkyl, etc.), which is then hydrolyzed to obtain the objective compound of formula V [e.g. p- methoxybenzyl-2-(3-amino-4-benzenesulfonylthio-2-azetidinon-1-yl)-3-ch loromethyl-3- butenoate]. |
