Lewis Acid-Catalyzed Chemodivergent and Regiospecific Reaction of Phenols with Quaternary Peroxyoxindoles

Building an All Carbon Quaternary Center via Redox-Neutral Geminal Dual C-H Functionalization of Oxindoles

Reported here is a catalytic redox-neutral geminal dual C-H functionalization of oxindoles with two distinct aromatics using anilines. The reaction proceeded through a pluripotent tetra-substituted alkene intermediate via an extended resonance stabilized carbocation. It furnished wide chemical space around oxindoles with the generation of all carbon quaternary centers (>35 examples) in good to excellent yields. The developed process is highly regioselective and scalable, and the conditions are environmentally benign in nature.

Catalyst-free coupling of peroxypyrroloindolenines with amines to afford stable peroxyindolenines

Here we report a highly efficient method for coupling of peroxypyrroloindolenines with amines under catalyst-free conditions to obtain stable C2-N peroxyindolenines in high yields with remarkable functional group tolerance. Initial studies have shown that compound 13 exhibits potent inhibition of the B16/F10 cell line with an IC50 value of 2.18 μM.

Green Late-Stage Functionalization of Tryptamines

An efficient and rapid protocol for the oxidative halogenation of tryptamines with 10 % aqueous NaClO has been developed. This reaction is featured by its operational simplicity, metal-free conditions, no purification, and high yield. Notably, the resulting key intermediates are suitable for further functionalization with various nucleophiles, including amines, N-aromatic heterocycles, indoles and phenols. The overall transformation exhibits broad functional-group tolerance and is applicable to the late-stage functionalization of complex biorelevant molecules.

DFT Study on Mechanism of Ni-Al Bimetallic-Catalyzed C-H Cyclization to Construct Tricyclic Imidazoles: Roles of NHC Ligand and AlMe3

The mechanism of the Ni-Al bimetallic-catalyzed C-H cyclization to construct tricyclic imidazoles is investigated using density functional theory calculations. The calculation result shows that the reaction mechanism involves sequential steps of substrate coordination, ligand-to-ligand hydrogen transfer (LLHT), and C-C reductive elimination to produce the final product tricyclic imidazole. The LLHT step is calculated to be the rate-determining step. The oxidative addition of the benzimidazole C-H bond to the Ni center and the insertion of the alkene into the Ni-H bond occur concertedly in the LLHT step. The effects of N-heterocyclic carbene (NHC) ligands and AlMe3 on the reactivity and regioselectivity were also analyzed. These calculation results shed light on some ambiguous suggestions from experiments.