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This paper describes easy access to twelve examples of five- and six-membered heterocycles (monocyclic and fused) containing a dimethyl acetal aldehyde function and/or a trifluoromethyl substituent, in good to excellent yields (72-98%). The dimethyl acetal-protected heterocycles were obtained in one-step via regioselective cyclocondensation reactions of 4,6,6-trimethoxy- 1,1,1-trifluorohex-3-en-2-one with 1,2-, 1,3- and 1,5-dinucleophiles (hydrazines, hydrazides, hydroxylamine, 1-acetylguanidine and 1,8-diaminonaphthalene). Subsequently, to demonstrate a potential synthetic application, some pyrazole rings containing dimethyl acetal moiety were converted to the respective secondary homoallylic alcohols by efficient allylation reactions employing allylaluminum reagent in 84 to 90% yields.

A simple and convenient procedure for the synthesis of a new series of 3-ethoxypyrrolidine-2,5- diones and cis-2,3,3a,6a-tetrahydrofuro(2,3-c)pyrrole-4,6(5H)-diones derivatives is described. All compounds were obtained from the direct cyclization of two β-cyanocarboxylic acids with primary amines and amino alcohols in short reaction time and good yields.

The one-pot and regioselective synthesis of a novel series of 3-aryl(heteroaryl)-5trifluoromethyl-5-hydroxy-4,5-dihydro-1H-pyrazolyl-1-carbohydrazides and bis-(3-aryl-5trifluoromethyl-5-hydroxy-4,5-dihydro-1H-pyrazol-1-yl)methanones from the cyclocondensation reactions of 4-alkoxy-4-aryl(heteroaryl)-1,1,1-trifluoroalk-3-en-2-ones, where aryl substituents are H, Me, Ph, 4-OMePh, 4-ClPh, 4-BrPh, 4,4’-biphenyl and heteroaryl are 2-thienyl and 2furyl, with carbohydrazide is reported.

The synthesis of a series of trifluoromethyl-cycloalka[b]quinolines (5a, 6a, 6c-e) in 15-30% yields, by intramolecular cyclization reactions of the readily available intermediates 2trifluoroacetyl-1-(arylamino)-cycloalkenes (3a-f and 4a-f) using poly-phosphoric acid (PPA) is reported. Compounds 3 and 4 are obtained from the reaction of 2-trifluoroacetyl-1methoxycycloalkenes 1 (n = 1 and 3) with six 4substituted anilines 2, where the 4substituents are Me, OMe, NO2, Cl, Br, I, in acetonitrile under reflux.

An improved procedure to prepare a series of five 5-alkoxy-1,1,1,2,2-pentafluoro-4-alken-3-ones (CF3CF2C(O)C(R 2 )=C(R 1 )OR, where R 2 /R = H/Et, H/Me, Me/Et, -(CH2)2- , -(CH2)3-, and R 1 = H, Me) in good yields (71 - 82%) and in an up to molar scale from the acylation reaction of enol ethers with pentafluoropropionic anhydride is described. These compounds were cyclocondensed with different dinucleophiles, such as hydroxylamine, 1,2-dimethylhydrazine and phenylhydrazine, to obtain a series of pentafluoroethyl substituted 4,5-dihydroisoxazoles, pyrazolium chlorides and pyrazoles, respectively, in one-pot procedures with moderate to very good yields (60 - 95%).