Rearrangement of cis- and trans-1-methyl-2-(2-thienyl)pyrrolidinium 1-methylides in a non-basic medium

Abstract

cis-1-Methyl-2-(2-thienyl)pyrrolidinium 1-methylide cis-2 generated in a non-basic medium isomerize to a mixture of (E)- and (Z)-5-methyl-3a,4,5,6,7,8-hexahydrothieno[3,2-c]azocine, (E)-6 and (Z)-6. The latter (Z)-6 has been cyclized to the cis-cisoid-cis-5-methyl-3a,6,7,8,8a,8b-hexahydro-4H-thieno[2′,3′-c]pyrrolo[1,2-a]pyrrolium salt 8 in water; trans-2 gives a mixture of 1-methyl-3-(2-thienyl)piperidine 7 and (E)-6 via a radical–cleavage and –recombination pathway.