Superelectrophilic Activation of Crotonic/Methacrylic Acids: Direct Access to Thiochroman-4-ones from Benzenethiols by Microwave-Assisted One-Pot Alkylation/Cyclic Acylation

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• 作者：Habiba Vaghoo ; G. K. Surya Prakash ; Arjun Narayanan ; Rohit Choudhary ; Farzaneh Paknia ; Thomas Mathew ; George A. Olah
• 刊名：Organic Letters
• 出版年：2015
• 出版时间：December 18, 2015
• 年：2015
• 卷：17
• 期：24
• 页码：6170-6173
• 全文大小：302K
• ISSN：1523-7052

文摘

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鈥揷arboxonium superelectrophilic species is suggested.