Copper-Catalyzed Radical Cascade Cyclization To Access 3-Sulfonated Indenones with the AIE Phenomenon

Abstract

An efficient copper-catalyzed radical cascade cyclization strategy was developed, by which a wide variety of 3sulfonyl substituted indenones were prepared in one pot via reaction of 2-alkynylbenzonitriles with sulfonyl hydrazides in the presence of TBHP and CuI under mild reaction conditions. Much more importantly, the 3-sulfonyl indenones, synthesized through our newly developed copper-catalyzed radical cascade cyclization strategy, were found to own typical aggregationinduced emission (AIE) properties, showing orange to red emission with large Stokes shift (more than 135 nm). In addition, such newly found AIEgens could be successfully used in live cell imaging, exhibiting excellent biocompatibility and application potential.

Efficient Thiolation of Alcohols Catalyzed by Long Chained Acid‐Functionalized Ionic Liquids under Mild Conditions

“…The reaction of aryl halides and thiols is the typical method to construct C‐S bonds . Researchers also built other important methods for the formation of thioethers, such as the addition of thiols to carbonyl compounds followed by the in‐situ reduction of the generated intermediate thionium ion, deoxygenation of sulfoxides, cross‐coupling of aryl boronic acids and alkyl thiols or N ‐thio(alkyl, aryl, heteroaryl)imides,, , metal catalyzed hydrothiolation of alkynes and so on . During the development of the system for synthesis of thioethers, significant progress has been made.…”

Alkyne Versus Ynamide Reactivity: Regioselective Radical Cyclization of Yne‐Ynamides

“…Only radical additions via 5-exo-dig cyclizations,which turn out to be the best computational options,a re discussed here.T he values are DG 343 in kcal mol À1 obtained at the UB3LYP [14] /6-311 ++G-(d,p) [15] level including solvent correction for CH 2 Cl 2 (PCM method [16] ;F igure 2). [20] Radical C is then likely to abstract ahydrogen atom from thiophenol to give D.T he latter should then easily tautomerize to the aromatic 4-thioaryl-pyrrole E,w hich displays the experimentally observed regiochemistry.I ft he benzothiyl radical attacks the internal ynamide carbon, vinyl radical H would be formed. [17] Starting from system A,c omprising am odel yne-ynamide and the benzothiyl radical, two pathways can provide pyrroles.T he radical can attack the internal propargyl alkyne carbon to give B, [18] which then undergoes a5 -exo-dig cyclization to yield C. [19] Thefirst step is endergonic by 9.2 kcal mol À1 ,and the second one is exergonic by 17.0 kcal mol À1 .T he corresponding transition states have free energies of 16.9 and 17.5 kcal mol À1 .…”

“…[17] Starting from system A,c omprising am odel yne-ynamide and the benzothiyl radical, two pathways can provide pyrroles.T he radical can attack the internal propargyl alkyne carbon to give B, [18] which then undergoes a5 -exo-dig cyclization to yield C. [19] Thefirst step is endergonic by 9.2 kcal mol À1 ,and the second one is exergonic by 17.0 kcal mol À1 .T he corresponding transition states have free energies of 16.9 and 17.5 kcal mol À1 . [20] Radical C is then likely to abstract ahydrogen atom from thiophenol to give D.T he latter should then easily tautomerize to the aromatic 4-thioaryl-pyrrole E,w hich displays the experimentally observed regiochemistry.I ft he benzothiyl radical attacks the internal ynamide carbon, vinyl radical H would be formed. Its transformation into the 5membered ring radical I,which displays an unobserved 2-thio regioselectivity,w as then modeled through a5 -exo-dig cyclization.…”

Alkyne Versus Ynamide Reactivity: Regioselective Radical Cyclization of Yne‐Ynamides

“…The first step is endergonic by 9.2 kcal mol −1 , and the second one is exergonic by 17.0 kcal mol −1 . The corresponding transition states have free energies of 16.9 and 17.5 kcal mol −1 . Radical C is then likely to abstract a hydrogen atom from thiophenol to give D .…”