Metal-free synthesis of indolo[2,3-b]indoles through aerobic cascade dehydrogenative aromatization/oxidative annulation

Abstract

A convenient method for the rapid construction of indolo[2,3-b]indoles has been developed. This cascade reaction involving condensation, dehydroaromatization, and oxidative annulation was achieved in a one-pot TMSI/DMSO system, providing a diversity of functionalized indolo[2,3-b]indoles in satisfactory yields under facile metal-free conditions. The present protocol provides a straightforward approach to access structurally valuable indolo[2,3-b], indoles.