Rhenium-Catalyzed [4 + 1] Annulation of Azobenzenes and Aldehydes via Isolable Cyclic Rhenium(I) Complexes

• DOI: 10.1021/acs.orglett.5b00938
• Publication Date: 2015-05-06T14:50:41Z
• Authors: Xiaoyu Geng; Congyang Wang
• Keywords: Annulation

The first Re-catalyzed [4 + 1] annulation of azobenzenes with aldehydes was developed to furnish 2H-indazoles via isolable and characterized cyclic ReI-complexes. For the time, acetate-acceleration effect is showcased in C–H activation reactions. Remarkably, mechanistic studies revealed an irreversible aldehyde-insertion step, which sharp contrast those previous Rh- Co-systems.