Synthesis of an Aminopyrazolidines Substituted Quinolone Acid

Abstract

Asynthesisof a new heterocycle.2~methyl-4~(>)~Cbz-am1nopyrazolidine ( 2 ) .and the preparation o f aminopyrazolidinesubst~tuted quinolone ac~d 1 are reported.In our continuing search for new qulnolone acid antibacterial agents, w e became interested in novel C-7 h e t e r o c y c l i c s u b s t i t u e n t s l H e r e i n w e r e p o r t t h e s y n t h e s i s o f ( S ) -2 -m e t h y l -4 -( S )benzyloxycarbonylaminopyrazolidine (2) and its reaction with 1cyclopropyl-6,7,8-trifluoro-1.4-dihydro-4-oxoquinoline-3-carboxylic acid (3) t o provide, after deprotection, t h e targeted compound 1-Forthe synthesis of quinolone acid U~83140A.we have developed a synthests o f aminopyrazolidine 2 ara trifluoroacetate salt (Scheme I and II) which uses Vederas' p-lactone 5, prepared according t o his procedure.2as a starting material.This lartone war reacted with rnethylhydrazine t o o b t a n hydraride6.No regioisomer o f 6 was observed in thir reaction.