Transition Metal-Catalyzed C–H Bond Alkynylation And Amidation Of Aryl Sulfonamides

The sulfonamide structural motif is prevalent in many pharmaceuticals,agrochemicals,and biologically active compounds and plays a significant role in their bioactivity.Significantly,the ortho-substituted benzenesulfonamides act as a key precursor for the synthesis of various benzosultams.In this thesis,we mainly investigated the transition metal（Rh,Ir）-catalyzed C-H bond activation/functionalization of aryl sulfonamides.A series of ortho-substituted sulfonamide derivatives have been synthesized;and this paper mainly includes two parts:（1）Rhodium-catalyzed direct C-H bond alkynylation of aryl sulfonamidesWe used N-acetylbenzenesulfonamide and triisopropylsilyl（TIPS）-substituted bromoalkyne as starting materials,[Cp*RhCl₂]₂ as catalyst,in the presence of Ag₂CO₃,LiOAc as the base,1,2-dichloroethane（DCE）as the solvent,and heated at 100°C under air atmosphere for 12h,a series of ortho-alkynylated benzene-sulfonamides compounds were obtained.Furthermore,triethylsilyl or trimethylsilyl（TES or TMS）-substituted bromo-alkyne was also amenable to the alkynylation,affording six-membered benzosultams via one-pot alkynylation/intramolecular cyclization cascade reaction.Mechanistic studies indicate that the reaction proceeds by a turnover limiting C–H activation step and a plausible mechanism was proposed.（2）Iridium catalyzed ortho-C-H Amination of aryl sulfonamidesWe also used N-acetylbenzenesulfonamide as starting materials and TsN₃ as an amination reagent,using[IrCp*Cl₂]₂ as the catalyst,in presence of AgNTf₂ and HOAc,in 1,2-dichloroethane（DCE）at 80°C for 12h to furnish ortho-amidated aryl sulfonamide in good to excellent yields.This strategy features a wide substrate scope,and tolerates a broad range of functional groups under external oxidant-free conditions.Furthermore,the sole by-product is N₂.In addition,the preliminary mechanism was investigated and the proposed reaction pathway was provided.