Aerobic Construction of 2-Acyl Benzoxazole by Tandem C—H Oxygenation and Oxazole Ring Formation

Abstract

The synthesis of useful 2-acyl benzoxazoles has been realized via the tandem methylene C-H oxygenation and oxazole annulation of N-(o-hydroxyphenyl)phenylacetamides via copper catalysis in one-pot fashion. Besides featuring the incomparable step-economy resulting from the multi-step transformation, the tunable synthesis of diverse 2-methylene functionalized benzoxazoles using identical starting materials as well as the expanded synthesis of corresponding benzothiazoles is also attractive advantage of the work.

Rapid One‐Pot Aerobic Oxidative N‐α‐C(sp3)‐H Functionalization of Arylmethylamines to Access Tetrasubstituted Imidazoles

“…Hence, the development of catalytic system under molecular oxygen or air as oxidant has been an increasing attention in the aerobic oxidation reactions development. [42][43][44][45][46][47][48][49][50] Traditionally, the Debus-Radziszewski imidazole synthesis meth-od is used to synthesize imidazoles by the carbonyl compounds and ammonium salts condensation. The different synthetic methods have been reported for preparation of trisubstituted imidazoles from isocyanides, nitriles, amino acids, imines, amides, and amidines substrates.…”

“…In recent years, the C−N bond functionalization under aerobic reactions becoming most important for designing different organic transformation in academics and industrial research. Hence, the development of catalytic system under molecular oxygen or air as oxidant has been an increasing attention in the aerobic oxidation reactions development [42–50] . Traditionally, the Debus‐Radziszewski imidazole synthesis method is used to synthesize imidazoles by the carbonyl compounds and ammonium salts condensation.…”

Gold-catalyzed synthesis of oxazoles from alkynyl triazenes and dioxazoles

“…For example, the oxazole structures in drug molecules could mimic biological interactions, providing increased metabolic stability. 2 Considering the significance of this type of aromatic five-membered nitrogen-containing heterocycle, the construction of oxazole skeletons has attracted considerable attention. 3 Typically, amine and carbonyl analogs are classical synthons for the construction of oxazoles, 4 and these methods mostly rely on bimolecular cycloaddition processes.…”

Recent advances in free radical cyclizations of 2-alkenyl benzaldehydes to synthesize benzocycloketones

“…Radical reactions, as a powerful tool in modern synthesis, have been rapidly developed in recent years, especially in combination with transition metal catalysis 8 and photocatalysis, 9 which enable radical-type couplings efficiently under mild radical excitation conditions. 8–10 2-Alkenyl benzaldehydes have been shown to be an excellent class of radical acceptors due to their unique structures in which unsaturated carbon–carbon double bonds and aldehyde groups coexist. They can be used to synthesize the valuable chroman-4-ols 11 and chroman-4-ones 12,13 through free radical intramolecular cyclization.…”