Acid-Promoted Multicomponent Tandem Cyclization to Synthesize Fully Substituted Oxazoles via Robinson-Gabriel-Type Reaction.

An acid-promoted multicomponent reaction for the synthesis of diverse fully substituted oxazole derivatives from simple and readily available arylglyoxal monohydrates, nitriles, and various C-nucleophiles has been developed. This protocol features wide functional group diversity which is capable of installing 4-hydroxycoumarin, 2-naphthol, and 1,3-cyclohexanedione motifs to oxazoles. Mechanistic analysis indicates that a classical Robinson-Gabriel reaction served as the key step for this tandem transformation.

Acid-Catalyzed Multicomponent Tandem Double Cyclization: A One-pot, Metal-free Route to Synthesize Polyfunctional 4,9-Dihydropyrrolo[2,1-b]quinazolines.

An acid-catalyzed multicomponent tandem double cyclization protocol has been developed for the synthesis of polyfunctional 4,9-dihydropyrrolo[2,1-b]quinazolines from simple and readily available arylglyoxal monohydrates, 2-aminobenzylamine, and trans-β-nitrostyrenes. This practical and metal-free reaction proceeds through an imine formation/cyclization/Michael addition/Henry cyclization protocol, resulting in the construction of four new bonds and two ring moieties directly in one pot.

Acid-Catalyzed Multicomponent Tandem Cyclizations: Access to Polyfunctional Dihydroindolizino[8,7-b]indoles.

An acid-catalyzed multicomponent tandem cyclization protocol has been developed for the synthesis of polyfunctional dihydroindolizino[8,7-b]indoles from simple and readily available arylglyoxal monohydrates, tryptamines, and trans-β-nitrostyrenes or malononitrile. This reaction represents a highly efficient and convenient methodology for the synthesis of diversely substituted heteropolycyclic scaffolds under mild, metal-free conditions.

Expeditious Synthesis of 2-Phenylquinazolin-4-amines via a Fe/Cu Relay-Catalyzed Domino Strategy.

A highly efficient Fe/Cu relay-catalyzed domino protocol has been developed for the synthesis of 2-phenylquinazolin-4-amines from commercially available ortho-halogenated benzonitriles, aldehydes, and sodium azide. This elegant domino process involved consecutive iron-mediated [3 + 2] cycloaddition, copper-catalyzed SNAr, reduction, cyclization, oxidation, and copper-catalyzed denitrogenation sequences. The formed structure is the privileged core in drugs and bioactive molecules.

Consecutive Cycloaddition/S(N)Ar/Reduction/Cyclization/Oxidation Sequences: A Copper-Catalyzed Multicomponent Synthesis of Fused N-Heterocycles.

A highly efficient multicomponent domino protocol has been developed for the synthesis of 5-phenyl-[1,2,3]triazolo[1,5-c]quinazolines from simple and readily available (E)-1-bromo-2-(2-nitrovinyl)benzenes, aldehydes, and sodium azide. This elegant domino process involved consecutive [3 + 2] cycloaddition, copper-catalyzed S(N)Ar, reduction, cyclization, and oxidation sequences. Notably, sodium azide acted as a dual nitrogen source in the construction of this novel fused N-heterocycle.

Intramolecular decarboxylative coupling as the key step in copper-catalyzed domino reaction: facile access to 2-(1,3,4-oxadiazol-2-yl)aniline derivatives.

A copper-catalyzed domino protocol for the synthesis of 2-(1,3,4-oxadiazol-2-yl)aniline derivatives has been developed from simple and available isatins and hydrazides. This domino process integrated consecutive condensation, base-promoted ring-opening and the key copper-catalyzed decarboxylative coupling for intramolecular C-O bond formation.