title: Thiol-ene "click" reaction triggered by neutral ionic liquid: the "ambiphilic" character of [hmim]Br in the regioselective nucleophilic hydrothiolation.
abstract: Thiol-ene "click" chemistry has emerged as a powerful strategy to construct carbon-heteroatom (C-S) bonds, which generally results in the formation of two regioisomers. To this end, the neutral ionic liquid [hmim]Br has been explored as a solvent cum catalyst for the synthesis of linear thioethers from activated and inactivated styrene derivatives or secondary benzyl alcohols and thiols without the requirement of using a metal complex, base, or free radical initiator. Furthermore, detailed mechanistic investigations using (1)H NMR spectroscopy and quadrupole time-of-flight electrospray ionization mass spectrometry (Q-TOF ESI-MS) revealed that the "ambiphilic" character of the ionic liquid promotes the nucleophilic addition of thiol to styrene through an anti-Markovnikov pathway. The catalyst recyclability and the extension of the methodology for thiol-yne click chemistry are additional benefits. A competitive study among thiophenol, styrene, and phenyl acetylene revealed that the rate of reaction is in the order of thiol-yne>thiol-ene>dimerization of thiol in [hmim]Br.
authors.affiliation: Natural Plant Products Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur-176061 (H.P.) (India); Academy of Scientific and Innovative Research (AcSIR), New Delhi (India).
authors.forename: Rajesh
authors.initials: R
authors.lastname: Kumar
authors.lastname: Saima
authors.forename: Amit
authors.initials: A
authors.lastname: Shard
authors.forename: Nitin H
authors.initials: NH
authors.lastname: Andhare
authors.lastname: Richa
authors.forename: Arun K
authors.initials: AK
authors.lastname: Sinha
mesh_terms: D001592:Benzyl Alcohols / Q000737:chemistry; D002384:Catalysis; D057930:Click Chemistry; D052578:Ionic Liquids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010636:Phenols / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013237:Stereoisomerism; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D001592:Benzyl Alcohols; D052578:Ionic Liquids; D010636:Phenols; D013438:Sulfhydryl Compounds; C042983:thiophenol
keywords: NMR spectroscopy; ambiphiles; click chemistry; ionic liquids; mass spectrometry