Research news, Nov. 4th, 2015
Cyclopentadiene-Phosphine/Palladium Catalyzed Synthesis of Indolizines from Pyrrole and 1,4-Dibromo-1,3-butadienes
Wei Hao, Han Wang, Qingyu Ye, Wen-Xiong Zhang, and Zhenfeng Xi*
Org. Lett. 2015, DOI: 10.1021/acs.orglett.5b02959
Indolizine is an important type of nitrogen-containing aromatic compounds. Introduction of multiple substituents is a difficult task to construct diversified indolizine derivatives. In this work, multi-substituted 1,4-dibromo-1,3-butadienes and pyrrole or indole are applied for the synthesis of multi-substituted indolizine derivatives. The Pd-catalyzed annulation process involves alkenyl or aryl C(sp2)-N bond formation followed by forming C(sp2)-C(sp2) bond via alkenylation of the α-C(sp2)-H bond of pyrrole and indole. The cyclopentadiene-phosphine ligand was found to be the best of the ligands examined.