鈥淩eported, but Still Unknown.鈥?A Closer Look into 3,4-Bis- and 3,4,5-Tris(trifluoromethyl)pyrazoles
文摘
Straightforward practical synthetic approaches to 3,4-bis- and 3,4,5-tris(trifluoromethyl)pyrazoles have been developed. The key step of the both syntheses is a transformation of the carboxylic group in a pyrazole core into the trifluoromethyl group by sulfur tetrafluoride. The elaborated synthetic protocols allow gram-scale preparation of the target products. The obtained compounds are comprehensively characterized by means of crystallographic analysis, determination of pKa values and fluorescence measurements.