Organophosphorus-Catalyzed "Dual-Substrate Deoxygenation" Strategy for C-S Bond Formation from Sulfonyl Chlorides and Alcohols/Acids

PIII/PV═O Redox Catalysis Mediated Thioesterification of Carboxylic Acids with Disulfides under Air Conditions

An efficient organophosphorus-catalyzed thiocarbonylation reaction of disulfides with carboxylic acids under air conditions was described. Various functional groups on carboxylic acids and disulfides can be tolerated under the present reaction conditions, affording thioesters in good to excellent yields. This method exhibited excellent chemoselectivity and can be applied for the late-stage functionalization of drug molecules containing a carboxylic acid group.

PIII/PV-Catalyzed Beckmann Reaction and Sequential [2,3]-Sigmatropic Rearrangement to Construct 2-Amidopyridines

An organophosphorus catalytic method for the synthesis of substituted 2-amidopyridines is reported. The method employs a small-ring organophosphorus-based catalyst and a hydrosilane reductant to drive the conversion of ketoximes and pyridine-N-oxides into 2-amidopyridines through sequential Beckmann rearrangement followed by [2,3]-sigmatropic rearrangement. The readily available ketoximes could be activated to nitrilium ions in PIII/PV redox catalysis and could efficiently participate in the domino reaction of pyridine-N-oxides, thus providing various substituted 2-amidopyridines in moderate to excellent yields. This presented strategy features excellent functional group tolerance and a broad substrate scope.

Organophosphorus-Catalyzed Direct Dehydroxylative Thioetherification of Alcohols with Hypervalent Organosulfur Compounds

A metal-free and thiol-free organophosphorus-catalyzed method for forming thioethers was disclosed, driven by PIII/PV═O redox cycling. In this work, one-step dehydroxylative thioetherification of alcohols was fulfilled with various hypervalent organosulfur compounds. This established strategy features an excellent functional group tolerance and broad substrate scope, especially inactivated alcohols. The scale-up reaction and further transformation of the product were also successful. Additionally, this method offers a protecting-group-free and step-efficient approach for synthesizing peroxisome proliferator-activated receptor agonists which exhibited promising potential for treating osteoporosis in mammals.

Synthesis of Phosphet-2-one Derivatives via Phosphinidene Transfer to Cyclopropenones

We report the first synthesis and structural characterization of free, uncomplexed phosphet-2-ones. These unsaturated four-membered phosphacycles were prepared by phosphinidene transfer from dibenzo-7-phosphanorbornadiene compounds, RPA (A = C14H10, anthracene), to cyclopropenones in yields of up to 89%. Theoretical studies suggest that the reaction proceeds through ketene-ylide and ketene-phosphaalkene intermediates. Further transformations of the phosphet-2-ones led to the isolation of more phosphet-2-ones and 1,2-dihydrophosphetes, including two furanone derivatives which are postulated to be produced by intramolecular phosphine-catalyzed [3 + 2] annulations.