CuI-catalyzed highly regioselective C H functionalization of indoles using indole-3-tosylhydrazones as carbene precursor: An efficient synthesis of 3,3-bis(indolyl)methane derivatives

Base‐Mediated Reductive Coupling of Indole‐3‐tosylhydrazone with Thiols/Boronic Acids: Facile Synthesis of 3‐(phenylthio)methyl/benzyl Indole Derivatives

“…Very recently, we have reported the synthesis of 3,3‐bis(indolyl)methane derivatives via CuI‐catalyzed regeioselective coupling of indole based N ‐tosylhydrzones with substituted indoles as the source of diazo in the reaction medium . Drawing encouragement from our recent work and advantages of transition‐metal free organic reactions, herein, we report the C‐3 functionalization of indole via transition metal free reductive coupling of indole‐3‐tosylhydrazone with thiols or boronic acids as the coupling partners. This protocol has a number of advantages over the previously reported carbene C−H functionalization of indoles such as no use of transition metal catalyst, no possiblity of competing reactions at C‐2 and N‐1 positions and no requirement of the library of diazo compounds.…”

Progress and prospects in copper-catalyzed C–H functionalization

“…A straight forward approach for the synthesis of 3,3-bis(indolyl) methane derivatives 96 was proposed by Tyagi and coworkers. 60 The copper catalyzed reaction between indole-3tosylhydrazones 95 and indole 35 took place optimally in the presence of CuI (10 mol%) as catalyst, Cs 2 CO 3 (2 equiv.) as base in 1,4-dioxane at 110 C for overnight (Scheme 33).…”

Methylene Surrogates for the Synthesis of 3,3’‐Diindolylmethanes

“…successfully described a way to form the 3,3' methylene bridge between two indole moieties using indole-3tosylhydrazones as the methylene donor (Scheme 48). [54] The process involves reaction between indole and indole-3-tosylhydrazone in the presence of CuI catalyst and Cs 2 CO 3 base in 1,4dioxane as solvent at an elevated temperature. Both symmetrical and unsymmetrical 3,3'-DIMs can be obtained in good yields.…”