Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work describes the application of the method of trifluoroacetic anhydride acetal acylation to four new functionalized ketones: 6-methyl-5-hepten-2-one, 4-phenyl-4- oxobutanoic acid (3-benzoylpropionic acid), 5-bromo-2-acetylthiophene and 2- propionylthiophene. The acylated products were obtained as β-trifluoromethyl ketones alkoxyvinyl and β-diketones. The product derived from 2-propionylthiophene was obtained as dihydrate, 3,3-dihydroxy-4,4,4-trifluoro-1-(2-thienyl)-2-butanone, its structure was confirmed by X-ray diffraction crystallography. The acylated dielectrophilic precursors were cyclized with dinucleophiles hydroxylamine, hydrazine, semicarbazide and thiosemicarbazide to form the corresponding 5-trifluoromethyl-4,5-dihydroisoxazoles, 5-trifluoromethyl-4,5-dihydro-1H-pyrazoles and trifluoromethyl-1H-pyrazole in good yields (>80%). The molecular structure of the synthesized products were assigned based on the data of 1H NMR, 13C and X-ray diffraction. / Este trabalho descreve a aplicação do método de acilação de cetais com anidrido trifluoracético, (CF3CO)2O, a quatro novas cetonas funcionalizadas: 6-metil-5-hepten-2- ona, ácido 4-fenil-4-oxobutanóico (ácido 3-benzoilpropiônico), 5-bromo-2-acetiltiofeno e 2-propioniltiofeno. Foram obtidos os produtos acilados na forma de β-alcoxivinil trifluormetil cetonas e β-dicetonas. O produto derivado do 2-propioniltiofeno foi obtido na forma de hidrato, o 3,3-dihidroxi-4,4,4-trifluor-1-(2-tienil)-2-butanona, sua estrutura foi confirmada por difração de raio-X em monocristal. Os precursores acilados dieletrofílicos foram ciclizados com dinucleofilos hidroxilamina, hidrazina, semicarbazida e tiosemicarbazida formando os respectivos 5-trifluorometil-4,5-diidroisoxazóis, 5- trifluorometil-4,5-diidro-1H-pirazóis e trifluorometil-1H-pirazóis em bons rendimentos (>80%). As estruturas moleculares dos produtos sintetizados foram atribuídas a partir dos dados de RMN 1H, 13C e difração de raios-X.