Photocatalytic Three‐Component Tandem Annulation Access to Multiply Substituted 1,2,4‐Triazole‐3,5‐diamines

Ionic-liquid-supported copper-promoted synthesis of 3,5-disubstituted-1,2,4-triazoles

The synthesis of triazoles plays an important role in drug discovery research. 1,2,4-triazoles are considered significant scaffolds among several bioactive heterocycles due to their extensive use in the pharmaceutical and agrochemical sectors. Consequently, the importance of the synthesis of 1,2,4-triazoles via a sustainable method has increased. Herein, we have utilized an ionic-liquid-supported copper(II) catalyst for the synthesis of 1,2,4-triazoles from benzonitrile derivatives and primary amines under neat conditions both in thermal and microwave heating approaches. Our approach furnished excellent yields of the target moieties (7a-r) in a comparatively short reaction time. This synthetic protocol provides the advantage of synthesizing a couple of C-N bonds and an N-N bond simultaneously from easily accessible amines and nitriles in a simple pathway via a sustainable approach.

Visible Light Mediated Chemoselective Hydroxylation of Benzylic Methylenes

We have developed a metal-free photocatalytic selective hydroxylation of benzylic methylenes to secondary alcohols. This approach utilizes low-cost eosin Y as photocatalyst, O2 as green oxidant, and inexpensive triethylamine as inhibitor for overoxidation. The mild reaction conditions enable the production of secondary alcohols with 56-95% yields, making it a promising and environmental-friendly method for the synthesis of secondary alcohols from benzylic methylenes.

Copper-Promoted Aerobic Oxidative [3+2] Cycloaddition Reactions of N,N-Disubstituted Hydrazines with Alkynoates: Access to Substituted Pyrazoles

A copper-promoted aerobic oxidative [3+2] cycloaddition reaction for the synthesis of various substituted pyrazoles from N,N-disubstituted hydrazines with alkynoates in the presence of bases is developed. This work involves a direct C(sp³)-H functionalization and the formation of new C-C/C-N bonds. In this strategy, inexpensive and easily available Cu₂O serves as the promoter and air acts as the green oxidant. The reaction exhibits the advantages of high atom and step economy, high regioselectivity, and easy operation.

Photocatalytic cross-dehydrogenative coupling reaction toward the synthesis of N,N-disubstituted hydrazides and their bromides

An efficient strategy for the divergent synthesis of N,N-disubstituted hydrazides and their bromides is reported through photoredox-catalytic cross-dehydrogenative coupling of N,N-disubstituted hydrazines and aldehydes.