PROCESS FOR THE SYNTHESIS OF AZETIDINONES

摘要

This invention provides a process for preparing the hypocholesterolemic compound (I) comprising: (a) reacting p-fluorobenzoylbutyric acid with pivaloyl chloride and acylating the product with a chiral auxiliary to obtain a ketone of formula (IV); (b) reducing the ketone of formula (IV) in the presence of a chiral catalyst to an alcohol; (c) reacting the chiral alcohol of step (b), an imine and a silyl protecting agent, then condensing the protected compounds to obtain a beta -(substituted-amino)amide of formula (VII); (d) cyclizing the beta -(substituted-amino)amide of formula (VII) with a silylating agent and a fluoride ion catalyst to obtain a protected lactam of formula (VIII); and removing the protecting groups. The intermediates of formulas (VII and VIII) are also claimed.