Homocouplings of Sodium Arenesulfinates: Selective Access to Symmetric Diaryl Sulfides and Diaryl Disulfides.

Symmetrical diaryl sulfides and diaryl disulfides have been efficiently and selectively constructed via the homocoupling of sodium arenesulfinates. The selectivity of products relied on the different reaction systems: symmetrical diaryl sulfides were predominately obtained under the Pd(OAc) catalysis, whereas symmetrical diaryl sulfides were exclusively yielded in the presence of the reductive Fe/HCl system.

Synthesis of 4-chalcogenyl pyrazoles via electrophilic chalcogenation/cyclization of α,β-alkynic hydrazones.

A facile method for the synthesis of 4-chalcogenylated pyrazoles has been developed via electrophilic chalcogenation/cyclization of α,β-alkynic hydrazones. The cyclization of α,β-alkynic aldehyde hydrazones could be induced by using either sulfenyl chloride or the S-electrophiles generated in situ from the reaction of NCS and arythiol. The developed method was successfully applied to the synthesis of the sulfenyl analogue of celecoxib.

-Alkynylthio Phthalimide: A Shelf-Stable Alkynylthio Transfer Reagent for the Synthesis of Alkynyl Thioethers.

A new kind of electrophilic alkynylthiolating reagent, called -alkynylthio phthalimide, is designed and synthesized herein. This electrophilic sulfenylating reagent can be easily prepared in three steps from commercially available phthalimide and corresponding silver acetylide. Furthermore, the -alkynylthio phthalimides are demonstrated to be efficient alkynylthio transfer reagents that can react with various C-nucleophiles, including β-ketoesters, aryl boronic acids, and Grignard reagents to afford a diverse range of alkynyl thioethers under mild conditions.

Rhodium-Catalyzed C-S and C-N Functionalization of Arenes: Combination of C-H Activation and Hypervalent Iodine Chemistry.

Rhodium-catalyzed sulfonylation, thioetherification, thiocyanation, and other heterofunctionalizations of arenes bearing a heterocyclic directing group have been realized. The reaction proceeds by initial Rh(III) -catalyzed C-H hyperiodination of arene at room temperature followed by uncatalyzed nucleophilic functionalization. A diaryliodonium salt is isolated as an intermediate, which represents umpolung of the arene substrate, in contrast to previous studies that suggested umpolung of the coupling partner.

O-Transfer-facilitated cyclizations of propargylamides with TMSN3: selective synthesis of tetrazoles and dihydroimidazoles.

An unprecedented formal [3+2] annulation of propargylamides with TMSN3 to deliver functionalized tetrazoles is developed. Oxygen-atom transfer (OAT) from the amide group to the C≡C bond was realized via a NIS-triggered-cyclization/ring-opening cascade pathway. The OAT process enables the amide to serve as a two-atom unit in the reactions.

Diaryliodoniums by Rhodium(III)-Catalyzed C-H Activation: Mild Synthesis and Diversified Functionalizations.

Diaryliodonium salts play an increasingly important role as an aryl source. Reported is the first synthesis of diaryliodoniums by rhodium(III)-catalyzed C-H hyperiodination of electron-poor arenes under chelation assistance. This C-I coupling reaction occurred at room temperature with high regio-selectivity and functional-group compatibility.

Rhodium(III)-catalyzed azacycle-directed intermolecular insertion of arene C-H bonds into α-diazocarbonyl compounds.

Cp*Rh(III)-catalyzed intermolecular C-C couplings between activated α-diazocarbonyl compounds and arenes bearing a range of azacyclic directing groups have been achieved. This catalytic alkylation reaction operates under mild conditions with good functional group tolerance.

Base-catalyzed cyclization of N-sulfonyl propargylamides to sulfonylmethyl-substituted oxazoles via sulfonyl migration.

The reaction of N-sulfonyl propargylamides in the presence of a base catalyst selectively affords 5-sulfonylmethyl oxazoles via 1,4-sulfonyl migration. Allenes have been established as the key intermediates. Experimental evidence has been provided to support a two-step mechanism in the cyclization.

Rhodium(III)-catalyzed C-C coupling between arenes and aziridines by C-H activation.

Making C-C from C-H: [{RhCp*Cl(2)}(2)]/AgSbF(6) (Cp*=pentamethylcyclopentadienyl) can regioselectively catalyze the C-C coupling of arenes with aziridines by a C-H activation pathway. An eight-membered rhodacyclic intermediate resulting from the insertion of the Rh-C bond into the aziridine was isolated.

Palladium-catalyzed desulfitative arylation of azoles with arylsulfonyl hydrazides.

Palladium-catalyzed desulfitative and denitrogenative arylation of azoles with arylsulfonyl hydrazides has been achieved. A broad scope of azoles and arylsulfonyl hydrazides has been used to produce arylated azoles in high yields.