ChemInform Abstract: Regioselective Acceptorless Dehydrogenative Coupling of N‐Heterocycles Toward Functionalized Quinolines, Phenanthrolines, and Indoles.

Abstract

A new strategy has been developed for the oxidant- and base-free dehydrogenative coupling of N-heterocycles at mild conditions. Under the action of an iridium catalyst, N- heterocycles undergo multiple sp 3 CH activation steps, generating a nucleophilic enamine that reacts in situ with various electrophiles to give highly functionalized products. The dehydrogenative coupling can be cascaded with Friedel- Crafts addition, resulting in a double functionalization of the N-heterocycles. Circumventing the use of stoichiometric oxidants, accept- orless dehydrogenation reactions have recently become a rapidly growing area of research. (1) These reactions produce H2 as the only byproduct, which is a valuable feedstock itself and energy carrier. (2) Not only can such reactions be applied to the synthesis of unsaturated compounds, they also allow for easy bond formation. Indeed, the last few years have witnessed the application of this novel acceptorless dehydro- genative coupling (ADC) strategy to the synthesis of many value-added compounds in a manner that is more straightfor- ward and economic and greener than the conventional