(Trifluoromethyl)thiolation of 2-Alkynylbenzoates: An Efficient Route to 4-[(Trifluoromethyl)thio]-1H-isochromen-1-ones

• Published in: European journal of organic chemistry Vol. 2014; no. 23; pp. 5017 - 5022
• Main Authors: Li, Yuewen, Li, Guangming, Ding, Qiuping
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.08.2014; WILEY‐VCH Verlag; Wiley; Wiley Subscription Services, Inc
• Subjects: Alkynes; Chemistry; Chemistry, Organic; Cyclization; Fluorine; Lewis acid catalysis; Oxygen heterocycles; Physical Sciences; Science & Technology; Sulfur; OXIDATIVE TRIFLUOROMETHYLTHIOLATION; Oxygen heterocycles; Fluorine; 3-SUBSTITUTED ISOCOUMARINS; Lewis acid catalysis; ARYL BORONIC ACIDS; Cyclization; ALPHA-PYRONES; HYPERVALENT IODINE REAGENT; ELECTROPHILIC TRIFLUOROMETHANESULFANYLATION; Sulfur; FACILE; CATALYZED TRIFLUOROMETHYLTHIOLATION; DERIVATIVES; Alkynes
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201402629

The incorporation of the (trifluoromethyl)thio group into the isocoumarin scaffold through a Lewis‐acid‐mediated electrophilic cyclization reaction of 2‐(2‐alkynyl)benzoates with trifluoromethanesulfanylamide is reported. The transformation proceeds well in the presence of BiCl3 and BF3·Et2O under mild conditions to give 4‐[(trifluoromethyl)thio]‐1H‐isochromen‐1‐ones regioselectively and in good yields. We describe a trifluoromethylthiolation/cyclization protocol for the synthesis of 4‐[(trifluoromethyl)thio]‐1H‐isochromen‐1‐ones through the reaction of 2‐(2‐alkynyl)benzoates with trifluoromethanesulfanylamide in good yields under mild conditions. A combination of the Lewis acids BiCl3 and BF3·Et2O serves as the activator for the transformation.