Fluorinated acetylenes. Part 8. Preparation and some reactions of 5,5,5-trifluoropent-3-yn-2-ol, 5,5,5-trifluoro-1-phenylpent-3-yn-2-ol and the derived ester, 2-acetoxy-5,5,5-trifluoropent-3-yne

Article abstract of DOI:10.1016/S0022-1139(00)80079-2

Treatment of the salt CF3C<*>CLi (3) with the aldehydes RCH2CHO (R = H and Ph) affords the secondary alcohols CF3C<*>CCHROH (1a) R = Me and (1b) R = CH2Ph.Alcohol 1a does not give the corresponding ketone on attempted oxidation (pyridinium chlorochromate or Na2Cr2O7/H2SO4), but alcohol 1b is oxidized to the diketone (CF3C<*>CCOCHPh)2 (7) (41percent) by active MnO2.The acetate CF3C<*>CCHMeO2CMe (2) undergoes facile reaction with diazomethane to give 3-<(1'-acetoxy)ethyl>-1-methyl-4-trifluoromethylpyrazole (10a) and hence the 3- and 5-<(1'-acetoxy)ethyl>-1-methyl-4-trifluoromethylpyrazoles (11a) and (12a), respectively.Cycloaddition also takes place between ester 2 and furan, but the major products (considered to be isomeric 1:1 adducts) have not been fully characterised.Although, ester 2 undergoes reaction with trifluoronitrosomethane, a cycloadduct has not been isolated, while nucleophilic attack by imidazole on the triple bond leads to the (Z)-alkene (18).