New routes for the synthesis of fused pyrrole scaffolds through transition metal-free tandem reactions

A series of transition metal-free tandem reactions for the synthesis of indolizines and 6,7-dihydroindolizin-8(5H)-ones by 4-bromobut-2-enoate ramifications reacted with 2-acetyl pyrrole derivatives are described. As the α-carbon changed from CH3, CH2Cl, CHCl2, to CCl3, different kinds of tandem reactions were observed. These tandem reactions could be used to synthesize fused indolizine and indolizidine scaffolds under mild and green conditions.