Pt(IV)-catalyzed hydroamination triggered cyclization: a strategy to fused pyrrolo[1,2-a]quinoxalines, indolo[1,2-a]quinoxalines, and indolo[3,2-c]quinolines

Abstract

A PtCl(4)-catalyzed hydroamination-triggered cyclization strategy to access biologically interesting N-containing heterocycles such as pyrrolo[1,2-a]quinoxalines, indolo[1,2-a]quinoxalines, and indolo[3,2-c]quinolines is described. The reaction makes use of aminoaromatics such as 1-(2-aminophenyl)pyrroles, N-(2-aminophenyl)indoles, 2-(2-aminophenyl)indoles, and alkynes having a tethered hydroxyl group. Mechanistically, the reaction is very appealing since it involves multiple catalytic cycles catalyzed by a single metal catalyst PtCl(4). We observed a remarkable enhancement of the rate when reactions were run under microwave-assisted conditions.