The stereoselective synthesis of e-1,2-bis(3-indolizinyl)ethylenes by the reactions of 3-thioformylindolizines with n-tributylphosphine

3-Thioformylindolizines undergo novel reductive coupling reaction in the presence of tributylphosphine to give E-1,2-bis(3-indolizinyl)ethylenes in high yield. These reactions proceed via (3-indolizinyl)methylene carbene intermediate and provide a new, stereoselective synthesis of the bis(3-indolizinyl)ethylene derivatives highly.