Synergistic Cooperative Effect of L‐Arginine‐[bmim]Br in Cascade Decarboxylative Knoevenagel‐Thia‐Michael Addition Reactions: Green Approach Towards C−S Bond Formation with In Situ Generated Unactivated α,β‐Unsaturated Ester

• DOI: 10.1002/adsc.201801150
• Publication Date: 2018-09-14T17:57:27Z
• Authors: Richa Singh; Yogesh Thopate; Danish Equbal; Arun K. Sinha
• Keywords: 01 natural sciences; 0104 chemical sciences

AbstractIn this report, a synergistic combination of L‐arginine and [bmim]Br has been realized for the first time towards step‐economical synthesis of β‐aryl‐β‐sulfanyl esters from aromatic aldehyde, malonate and thiol via cascade thia‐Michael addition reaction on in situ formed unactivated β‐aryl‐α,β‐unsaturated esters (via decarboxylative Knoevenagel reaction) under metal‐and acid/base‐free conditions. Furthermore, the gram scalability and recyclability of the catalytic system (up to 5 cycles) makes our one‐pot two‐step protocol more economically efficient and synthetically attractive for cascade C−C and C−S bond formation than traditional two‐step methods. The synergistic interaction of the catalytic system i. e. L‐arginine with [bmim]Br has been probed by NMR (1H and 13C) studies.magnified image