2-perfluoroalkanoylcyclopentane-1,3-diones. Synthesis and some transformations

2-Perfluoroalkanoylcyclopentane-1,3-diones were synthesized for the first time by acylation of cyclopentane-1,3-dione with perfluorocarboxylic acids in the presence of 1,1??-carbonyldiimidazole or with perfluorocarboxylic anhydrides in the presence of imidazole. 2-Perfluoroalkanoylcyclopentane-1,3-diones were selectively reduced to 2-(1-hydroxyperfluoroalkyl)cyclopentane-1,3-diones by the action of triethylsilane in trifluoroacetic acid in the presence of a catalytic amount of lithium perchlorate. Treatment of the title compounds with oxalyl chloride and subsequent reaction with 2 equiv of primary amine (4-fluoroaniline, 4-fluorobenzylamine, 3,4-difluoroaniline, 3-trifluoromethylbenzylamine) gave the corresponding 3-arylamino-2-perfluoroalkanoylcyclopent-2-en-1-ones.