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1 = n-decyl] were synthesized from respective alkyl methyl ketones or aldehyde via acetal acylation using trifluoroacetic anhydride and trichloroacetyl chloride. 1,1,1-Trihalo-4-methoxy-3-alken-2-ones with acid-compatible substituents were easily hydrolyzed to respective trihalomethyl-1,3-diketones. The 1,1,1-trihalo-4-methoxy-3-alken-2-ones and/or respective trihalomethyl-1,3-diketones were reacted regiospecifically with hydroxylamine hydrochloride, leading to isoxazole derivatives, and with hydrazines, leading to respective 1H-pyrazole derivatives. The structures of all compounds were assigned based on nuclear magnetic resonance (NMR) and mass spectrometric data. This method represents an efficient pathway for the regioselective trihaloacetylation of asymmetrically substituted alkyl methyl ketones and highly self-condensing aldehydes. Moreover, this approach allows the introduction of biologically recognizable moieties, such as those from levulinic acid, sulcatone (prenyl), benzylacetone, anisylacetone, and raspberry ketone, as synthetic molecular targets.

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Microwave-Assisted Synthesis of 5-Hydroxy-5-trichloromethyl-4,5dihydroisoxazoles.-The cyclocondensation of 4-alkoxy-1,1,1-trihalo-3-alken-2-ones (I) with hydroxylamine yielding dihydroisoxazoles (II) is remarkably accelerated by microwave irradiation. -(MARTINS, MARCOS A. P.; BECK, PAULO; CUNICO, WILSON; PEREIRA, CLAUDIO M. P.; SINHORIN, ADILSON P.; BLANCO, ROGERIO F.; PERES, RODRIGO; BONACORSO, HELIO G.; ZANATTA, NILO; Tetrahedron Lett. 43 (2002) 39, 7005-7008; Dep. Quim., Univ. Fed.

Pyrazole derivativesPyrazole derivatives R 0180 5-Trifluoromethyl-1,2-dimethyl-1H-pyrazolium Chlorides: Synthesis and 1 H, 13 C, 19 F and 35 Cl NMR Chemical Shifts. -(MARTINS*, M. A. P.; BLANCO, R. F.; PEREIRA, C. M. P.; BECK, P.; BRONDANI, S.; CUNICO, W.; ZIMMERMANN, N. E. K.; BONACORSO, H. G.; ZANATTA, N.; J. Fluorine Chem. 118 (2002) 1-2, 69-72; Dep. Quim., Univ. Fed. Santa Maria, 97105 Santa Maria, Brazil; Eng.) -R. Langenstrassen 11-124