title: Superelectrophilic Activation of Crotonic/Methacrylic Acids: Direct Access to Thiochroman-4-ones from Benzenethiols by Microwave-Assisted One-Pot Alkylation/Cyclic Acylation.
abstract: An efficient microwave-assisted protocol for the synthesis of 2-/3-methylthiochroman-4-ones by superacid-catalyzed alkylation followed by cyclic acylation (cyclization via intramolecular acylation) is described. Using easily accessible benzenethiols and crotonic acid/methacrylic acid with triflic acid (as catalyst of choice for needed optimal acidity), the reaction was tuned toward the formation of the cyclized products in good selectivity and yield. A mechanism involving the formation of carbenium-carboxonium superelectrophilic species is suggested.
authors.affiliation: Department of Chemistry and Biochemistry, Colorado College , Colorado Springs, Colorado 80903-3243, United States.
authors.forename: Habiba
authors.initials: H
authors.lastname: Vaghoo
authors.affiliation: Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California , Los Angeles, California 90089-1661, United States.
authors.forename: G K Surya
authors.initials: GK
authors.lastname: Prakash
authors.affiliation: Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California , Los Angeles, California 90089-1661, United States.
authors.forename: Arjun
authors.initials: A
authors.lastname: Narayanan
authors.affiliation: Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California , Los Angeles, California 90089-1661, United States.
authors.forename: Rohit
authors.initials: R
authors.lastname: Choudhary
authors.affiliation: Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California , Los Angeles, California 90089-1661, United States.
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Paknia
authors.affiliation: Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California , Los Angeles, California 90089-1661, United States.
authors.forename: Thomas
authors.initials: T
authors.lastname: Mathew
authors.affiliation: Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California , Los Angeles, California 90089-1661, United States.
authors.forename: George A
authors.initials: GA
authors.lastname: Olah
mesh_terms: D002384:Catalysis; D002867:Chromones / Q000138:chemical synthesis* / Q000737:chemistry; D003437:Crotonates / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D008689:Methacrylates / Q000138:chemical synthesis* / Q000737:chemistry; D008872:Microwaves; D015394:Molecular Structure; D010636:Phenols / Q000138:chemical synthesis* / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D002867:Chromones; D003437:Crotonates; D008689:Methacrylates; D010636:Phenols; D013438:Sulfhydryl Compounds; C008384:methacrylic acid; C042983:thiophenol