Palladium-catalysed cyclisation of ynamides and propargyl tethered iodosulfonamides with boronic acids leading to benzosultams

Base-promoted cascade 5-exo-dig annulation/carboxylation of o-(1-alkynyl)benzenesulfonamides with CO2: divergent synthesis of mono- or gem-dicarboxylic esters

A base-promoted cascade 5-exo-dig cyclization/carboxylation of o-alkynylsulfamides with CO2 has been accomplished, furnishing a variety of benzosultam-containing acrylates in good yields by using CO2 as the carboxylic source. Notably, in the case of substrates bearing a TMS-alkyne motif, the gem-dicarboxylation products were generated unprecedentedly.

Iron-Catalyzed Synthesis of Benzosultams from N-Phenyl-N-(prop-2-yn-1-yl)benzenesulfonamide and Benzenesulfonyl Hydrazine

A novel route for an iron-catalyzed tandem sulfonylation, C(sp²)-H activation, cyclization reaction which uses N-phenyl-N-(prop-2-yn-1-yl)benzenesulfonamide and benzenesulfonohydrazide to synthesize derivatives of (Z)-2-phenyl-4-((phenylsulfonyl)methylene)-3,4-dihydro-2H-benzo[e][1,2]thiazine 1,1-dioxide has been developed. The method features convenient operation and good functional group tolerance. In addition, it employs insensitive and inexpensive FeSO₄ as the catalyst and provides a direct approach for the preparation of benzothiazides.

PhI(OAc)2-mediated trifluoromethylthiolation/oxidative cyclization of ynamides

A PhI(OAc)₂-mediated trifluoromethylthiolation/oxidative cyclization of ynamides with the Shen reagent has been established herein, providing a facile access to CF₃S-substituted oxazolidine-2,4-diones bearing a quaternary carbon center in 38-85% yields with chemoselectivities of up to 99/1.