We describe a three-component reaction of o-iodoanilines with K2S and DMSO that provides 2-unsubstituted benzothiazoles in moderate to good isolated yields with good functional group tolerance. Electron-rich aromatic amines and o-phenylenediamines instead of o-iodoanilines provided 2-unsubstituted benzothiazoles and 2-unsubstituted benzimidazoles with and without K2S under similar conditions. Notably, DMSO plays three vital roles: carbon source, solvent, and oxidant.

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A NiCl 2 -promoted [2 + 2 + 1] carboannulation of 1,7-enynes with internally oxidative cyclobutanone oximes to produce canyo-functionalized 4H-cyclopenta[c]quinolin-4-ones is disclosed. Through C−C/N−O bond cleavage and C−H functionalization, the process enables one-carbon incorporation using cyclobutanone oximes to achieve [2 + 2 + 1] carboannulation of 1,7-enynes, which is highlighted by allowing the formation of four new bonds with high selectivity and broad substrate scope.

An alternative entry to transformations of N-sulfonyl-4-(2-(ethynyl)aryl)-1,2,3-triazoles with various generated in situ or external nucleophiles by means of silver catalysis for producing diverse functionalized isoquinolines is described. Mechanistically, the reaction is proposed to involve a key silver carbenoid intermediate, thus enabling the formation of multiple chemical bonds via ring opening, N extrusion, silver carbenoid formation, nucleophilic addition, and complex annulations cascades.