Synthesis of unsymmetrical annulated 2,2′-bipyridine analogues with attached cycloalkene and piperidine rings via sequential diels-alder reaction of 5,5′-bi-1,2,4-triazines

Abstract

Synthesis of bisfunctionalized unsymmetrical 2,2′-bipyridines 8 or their sulfonyl derivatives 12a,b are described. They were prepared via the Diels-Alder reaction of 1-methyl-4-pyrrolidin-1-yl-1,2,3,6-tetrahydropyridine (6) with 3,3′-bis(methylsulfanyl)-5,5′-bi-1,2,4-triazine (1). The reaction leads to the single cycloaddition product 7 which undergoes Diels-Alder reaction with cyclic enamines 2a,b to give unsymmetrical 2,2′-bipyridine derivatives 8, consisting of the two different heterocyclic units: cycloalkeno[c]pyridine and 2,6-naphthyridine. © 2005 by MDPI.