Fe-S Catalyst Generated In Situ from Fe(III)- and S3•--Promoted Aerobic Oxidation of Terminal Alkenes

Selective Synthesis of Vinyl Sulfides or 2-Methyl Benzothiazoles from Disulfides and CaC2 Mediated by a Trisulfur Radical Anion

In this report, we have established a novel and efficient method for selectively synthesizing either vinyl sulfides or 2-methylbenzothiazoles from the reaction of CaC2 and disulfides. The selective synthesis of these two distinct products can be controlled by simply adjusting the amount of K2S. The underlying reaction mechanism has been thoroughly investigated through control experiments, HRMS, and FTIR, which collectively support the pivotal role of a trisulfur radical anion. This radical species, generated in situ from K2S, is essential for the homolytic cleavage of the S-S bonds in a catalytic manner. Additionally, the trisulfur radical anion also acts as an effective mediator for activating the vinyl group of 2-aminophenyl vinyl sulfides, facilitating the crucial intramolecular cyclization required to produce 2-methylbenzothiazoles. Moreover, CaC2 not only serves as an acetylene source but also creates the basic conditions essential for the selective formation of vinyl sulfides. This methodology demonstrates broad substrate compatibility and excellent functional group tolerance, significantly enhancing its practical utility in diverse synthetic applications.

Synthesis of unsymmetrical ketones via dual catalysed cross-coupling of α,β-unsaturated carboxylic acids with aryldiazonium salts

A visible light-enabled synthesis of unsymmetrical ketones has been accomplished by the cross-coupling of α,β-unsaturated carboxylic acids and aryldiazonium salts embracing a synergistic eosin Y and Co(OAc)2·4H2O catalysis. The reaction involves decarboxylative aerobic CC bond cleavage, and is endowed with the creation of new C-C and C-O bonds with good substrate scope.

Elemental sulfur generated in situ from Fe(III) and sulfide promotes sulfidation of microscale zero-valent iron for superior Cr(VI) removal

Herein, we compared the effect of different extra iron and sulfur precursors on the sulfidation efficiency, physicochemical properties, and reactivity of post-sulfidated microscale zero-valent iron (S-ZVI). S⁰@ZVI was synthesized from in situ S⁰ generated via reaction of Fe(III) with S^2-, which resulted in 23-fold higher Cr(VI) removal compared with S⁰_com/ZVI synthesized using commercial S⁰. The direct formation of FeS_x film via reaction between S⁰ and ZVI played a crucial role in enhancing the removal of Cr(VI) by S⁰@ZVI, with 16- and 12-fold faster rates compared with FeS@ZVI and FeS₂@ZVI prepared via precipitated reaction of Fe(II) with S^2- and sulfur mixtures, respectively. The incorporated sulfur, sulfidation sequence, and sulfidation time determined the performance of S⁰@ZVI. A combination of batch experiments and kinetic models was used to determine the chemical composition of reduced Cr(VI) products. S⁰@ZVI immobilized Cr(VI) as Fe_0.5Cr_0.5(OH)₃ via surface heterogeneous reactions, and partial Cr(VI) was homogeneously reduced to soluble Cr(acetate)₃ or Fe_0.75Cr_0.25(OH)₃(aq) by dissolved Fe(II). The insights gained from this study will facilitate the fabrication of highly reactive S-ZVI and elucidate the mechanism of Cr(VI) removal.

Palladium-Catalyzed Cross-Coupling of Cyanohydrins with Aryl Bromides: Construction of Biaryl Ketones

The palladium-catalyzed cross-coupling of the lithium anion of aryl tert-butyldimethylsilyl protected cyanohydrins with aryl bromides followed by in situ deprotection with fluoride ion provides a convenient and versatile approach to biaryl ketones. This protocol represents the first example of a palladium-catalyzed arylation of a cyanohydrin, which functions as an acyl anion equivalent. Hence, in contrast to classical cross-coupling reactions, the pronucleophile component is incorporated in the product to permit further functionalization. We then highlight the synthetic utility of the new method with applications to bioactive biaryl ketones and the construction of a triaryl diketone that was used to prepare an extended tetrathiafulvalene.