FLUORINATED ACETYLENES .11. REACTION OF [1,1-BIS(3,3,3-TRIFLUOROPROPYNYL)]ETHYL ETHANOATE WITH CYCLOHEXA-1,3-DIENE AND OF [ALPHA,ALPHA-BIS(3,3,3-TRIFLUOROPROPYNYL)]BENZYL BENZOATE WITH NORBORNADIENE AND DIAZOMETHANE

The reaction of cyclohexa-1,3-diene with the dialkynyl ester (CF3C=C)2CMeO2CMe (1a) at 70-degrees-C gives a mixture of two diastereomers (ratio 9:2) of the Diels-Alder adduct [2-(2-acetoxy-5,5,5-trifluoropent-3-yn-2-yl)-3-trifluoromethyl]bicyclo[2.2.2]octa-2,5-diene (3), which on thermolysis at 100-degrees-C affords mainly 2-(2-acetoxy-5,5,5-trifluoropent-3-yn-2-yl)benzotrifluoride (4) together with a small amount of its hydration product 2-(2-acetoxy-5,5,5-trifluoropent-3-one-2-yl)benzotrifluoride (5). Attempted cycloaddition between norbornadiene and the corresponding benzoate ester (CF3C=C)2CPhO2CPh (1b) at 150-degrees-C gave a complex mixture of unidentified products; reaction did not occur at 100-degrees-C. Facile reaction occurred between diazomethane and the ester 1b at 0-degrees-C to give [alpha,alpha-bis(4-trifluoromethylpyrazol-3-yl)]benzyl benzoate (16) and [alpha-(1-methyl-4-trifluoro-methylpyrazol-5-yl)-alpha-(4-trifluoromethylpyrazol-3-yl)]benzyl benzoate (15) and hence [alpha,alpha-bis(1-methyl-4-trifluoromethyl pyrazol-3-yl)benzyl benzoate (17), [alpha-(1-methyl-4-trifluoropyrazol-3-yl)-alpha-(1-methyl-4-trifluoromethylpyrazol-5-yl)]benzyl benzoate (14) (major product) and [alpha,alpha-bis(1-methyl-4-trifluoromethylpyrazol-5-yl)]benzyl benzoate (13).