A Co­(III)-catalyzed novel [4 + 2] annulation of N-chlorobenzamides with maleimides has been reported. Mostly, maleimides are known to furnish the Michael-type or 1,1-type cyclized products while treating with amides. In this reaction, maleimides furnished [4 + 2] annulated products in good yields at room temperature while being treated with the internal oxidizing N-chlorobenzamide as a directing group. The developed methodology is compatible with a variety of functional groups. The [4 + 2] annulated products obtained are featured in some biologically active molecules.

Selenocyanation and thiocyanation of electron rich arenes have been achieved using N‐iodosuccinimide (NIS) as a catalyst and aq. tert‐butyl hydroperoxide (TBHP) as an oxidant at room temperature. This method works efficiently for indoles, anilines, phenols, and other electron‐rich arene systems to furnish the products in good to excellent yields and exhibits a good regioselectivity. The products synthesized are further used to prepare their corresponding trifluoromethyl derivatives using reported reactions.

Highly selective azo directed 1,4-addition of an ortho C-H bond to maleimides has been developed using Co(III) catalyst. This reaction furnishes 3-arylated succinimide derivatives in good yields with excellent selectivity. This protocol exhibits a broad substrate scope and is compatible with symmetrical and unsymmetrical azobenzene derivatives, with maleimides and maleate esters. Preliminary deuterium incorporation studies have been performed to understand the mechanism of the reaction.

The cobalt(III)-catalyzed site-selective C-2 functionalization of indole has been developed using the pyrimidinyl group as a directing group. This reaction furnishes 3-arylated succinimide derivatives in excellent yields in a shorter duration using an inexpensive Co catalyst. Highly selective C-2 functionalization of indoles was achieved in the presence of the highly reactive C-3 position. This protocol is compatible with a variety of N -pyrimidinyl indole and maleimide derivatives, and it can be easily scaled-up. This method is also applicable for maleic ester and heteroarenes.

A manganese-catalyzed CÀ H bond alkenylation of indoles at C2-position with 4-hydroxy-2alkynoates leading to concomitant lactonization under removable directing group strategy has been disclosed. This lactonization strategy exhibits regioselectivity, a broad substrate scope, and a good functional group tolerance furnishing the products in low to high yields. The regioselectivity is guided by the electronic effect of the ester group as well as the steric bulk at the C4-position of the 4-hydroxy-2-alkynoates. After the reaction, the directing group has been readily removed to obtain NÀ H free indole. Scheme 1. Comparision of prevoius works with this work. Scheme 2. Substrate scope of indole and pyrrole derivatives.Scheme 4. Substrate scope of indole and other (hetero)aromatics compounds. Scheme 5. Scaling-up reaction and synthetic utility.