A Novel and Simple Synthesis of 2-(Trifluoromethyl)-4H-thiochromen-4-ones

Abstract

Alkyl 2-mercaptophenyl ketones react with trifluoroacetic anhydride in the presence of triethylamine to give 2-(trifluoromethyl)-4H-thiochromen-4-ones, which are transformed into the corresponding pyrazoles by treatment with hydrazine hydrate and into 1,1-dioxides by oxidation with H₂O₂ in AcOH.

Keywords:

• 2-(Trifluoromethyl)-4H-thiochromen-4-one and their 1, 1-dioxides
• alkyl 2-mercaptophenyl ketones
• pyrazoles

Acknowledgments

This work was financially supported by the Deutsche Forschungsgemeinschaft (Grant No. 436 RUS 113/758/1-1) and by the U.S. Civilian Research and Development Foundation and Russian Federation Ministry of Education (Grants EK-005-X1 and Y1-005-04). We are very grateful to T. Dülcks, Institute of Organic Chemistry, University of Bremen, Germany, for recording the mass spectra.