α‐Amino Acid Sulfonamides as Versatile Sulfonylation Reagents: Silver‐Catalyzed Synthesis of Coumarins and Oxindoles by Radical Cyclization

Abstract

We developed a silver‐catalyzed strategy for the generation of sulfonyl radicals from sulfonamides derived from α‐amino acids. The reaction proceeded via a decarboxylation, N–S bond cleavage and radical cyclization sequence and allows the difunctionalization of alkynes and the synthesis of 3‐sulfonylated coumarins. The reaction tolerated a broad scope of substrates and functional groups and could be extended to the synthesis of oxindoles and an isoquinolinedione by the capturing of the sulfonyl radical with an alkene moiety. Moreover, the proposed mechanism was supported experimentally and by DFT calculations.

Iodine-Catalyzed Synthesis of Chiral 4-Imidazolidinones Using α-Amino Acid Derivatives via Dehydrogenative N–H/C(sp3)–H Coupling

“…Recently, the Muñiz group demonstrated that this transformation can be carried out using catalytic iodine under light irradiation to synthesize pyrrolidine derivatives . On the basis of this precedent and our ongoing interest in using amino acids as precursors and templates for efficient organic synthesis, we herein demonstrate the iodine-catalyzed synthesis of 4-imidazolidinone derivatives using substrates prepared from readily available α-amino acids and alkylamines.…”

I+/TBHP Catalysis For Tandem Oxidative Cyclization To Indolo[2,3‐b]quinolines

“…From the control experiment using DPE, we obtained two major side products, which were unambiguously determined to be nosyl hydroperoxide 9 and its reduced form 10 by X-ray analysis (Scheme 7b). These results clearly indicated the generation of nosyl radical species [16] that would be trapped by DPE to give a Markovnikov adduct, which was further captured by O 2 to give nosyl hydroperoxide 9 under air.…”

Recent Advances in the Synthesis of Coumarin and Its Derivatives by Using Aryl Propiolates

“…as an oxidant in MeCN/H 2 O (2 : 1) solvent at 50 °C temperature (Scheme 29). [41] Sulfonamides made from alanine, phenylalanine, and glycine formed low yields, whereas good yield was obtained from valine and 2‐methylalanine derived sulfonamides. Importantly, as the catalyst concentration was lowered to 5 mol%, the yields were lowered, and the starting material was restored.…”