Generation of Organo Copper Species in Organotin/Coppter (I) Systems and Application to Carbon-Carbon Bond Formation

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Generation of organocopper species in organotin/copper (I) chloride systems and applicatoins t to new carbon-carbon bond formaiton have been investigated. The generation and reaction of alkenylcopper (I) species in alkenyltins/copper (I) chloride/NMP systems could open new synthetic routes to 3-alkenyl-DELTA^3-cephems and 3-alkenyl-DELTA^2-cephems, respectively. The presence of bipyridine or terpyridine in the reaction media stabilized the copper species effectively to promote alkenylation of 3-chloromethylcephem. Similar copper (I) species could be generated by direct reaction of allylic or benzylic halides with copper powder in NMP in the presence of bipyridine or terpyridine. Homocoupling and heterocoupling of 3-chloromethyl-cephem were successfully achieved by use of the in situ generated copper species.A combination of tin hydride and copper (I) chloride in NMP was also investigated, in which, coordinatively unsaturated copper (I) hydride species were formed. Reaction of the in situ generated copper (I) hydride with allenecarboxylate, alkenyl triflate, and allylic halides proceeded smoothly to offer new synthetic schemes of 3-norcephem, its DELTA^2-isomer, and 3-exo-methylenecepham. The organocopper species innovated in this research project are far different from those preapred by the conventional methods. Further applications of the organocopper species are now in progress.