Phosphine-Catalyzed [4 + 1] Annulation between α,β-Unsaturated Imines and Allylic Carbonates: Synthesis of 2-Pyrrolines
作者:Junjun Tian、Rong Zhou、Haiyun Sun、Haibin Song、Zhengjie He
DOI:10.1021/jo200164v
日期:2011.4.1
In this report, a phosphine-catalyzed [4 + 1] annulationbetween α,β-unsaturated imines and allylic carbonates is described. This reaction represents the first realization of catalytic [4 + 1] cyclization of 1,3-azadienes with in situ formed phosphorusylides, which provides highly efficient and diastereoselective synthesis of 2-pyrrolines.
A pyridine-catalyzed ylide cyclization affording dihydrofurans and dihydropyrroles has been developed. In the presence of a catalytic amount of pyridine and Fe(Tcpp)Cl, α-ylidene-β-diketones and α,β-unsaturated imines react with diazoacetates providing dihydrofurans and dihydropyrroles respectively, in up to 96% yield with high diastereoselectivities.