Oxidative Control of Photoinduced Cascade Electrocyclizations in Aromatic Azido Imines to Access Complex Fused Imidazoles or Pyrazoles

Abstract

Photoinduced cascade of two 6π-electron six-and five-center electrocyclizations in aromatic azido imines is oxidatively controlled to yield complex fused benzimidazoles or indazoles. Formation of benzimidazoles occurs via an unprecedented carbon-to-nitrogen o-iminoaryl 1,2-shift.

Visible light-induced reductive aza-6π electrocyclization access to phenanthridines

“…For instance, high temperatures or pressures, or short-wavelength UV lights, are restricted by a narrow substrate scope or special reactor (Scheme 1c). Nowadays, many aza-6π electrocyclization reactions are designed as a single step in cascade reactions or derivatization 9 without avoiding harsh reaction conditions. Thus, the development of a visible light-driven, benign and efficient aza-6π electrocyclization for the synthesis of phenanthridines is still highly desirable.…”