A general approach to construct selenopheno[3,2-b]indole-cored molecules using Fischer indolization

Abstract

A wide series of various selenopheno[3,2-b]indole-based compounds, including 2-aryl-substituted selenopheno[3,2-b]indoles as well as derivatives of benzo[4,5]selenopheno[3,2-b]indole, pyrido[3′,2′:4,5]selenopheno[3,2-b]indole, pyrazino[2′,3′:4,5]selenopheno[3,2-b]indole and chromeno[3′,4′:4,5]selenopheno[3,2-b]indol-6-one, were prepared from the appropriate 3-aminoselenophen-2-carboxylates via a one-pot two-step procedure based on the Fischer indole synthesis. The present synthetic strategy includes the conversion of 3-aminoselenophen-2-carboxylates into 2-unsubstituted 3-aminoselenophenes, their C-2 protonation to form selenophen-3(2H)-iminium cations, and the reaction of these iminium intermediates with arylhydrazines to obtain arylhydrazones of selenophen-3(2H)-ones followed by their Fischer indolization affording selenopheno[3,2-b]indole molecules.