Cp*Co^III-Catalyzed Synthesis of Pyrido[2′,1′:2,3]pyrimido[1,6-<i>a</i>]indol-5-iums via Tandem C–H Activation and Subsequent Annulation from 1-(Pyridin-2-yl)-1<i>H</i>-indoles and Internal Alkynes

Abstract

A Cp*Co III -catalyzed C2-selective C–H alkenylation/annulation cascade transformation of 1-(pyridin-2-yl)-1 H -indoles with internal alkynes to afford pyrido[2′,1′:2,3]pyrimido[1,6- a ]indol-5-iums is presented. Moreover, 6,7-dihydro-4 H -pyrido[2′,1′:2,3]pyrimido[1,6- a ]indole, a new functionalized N -fused indole core heterocycle, could be constructed effectively via reduction of pyrido[2′,1′:2,3]pyrimido[1,6- a ]indol-5-ium by NaBH 4 .