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The synthetic versatility of 4-alkoxy-4-alkyl/aryl-1,1,1-trichloroalk- 3-en-2-ones (enones) for the synthesis of [1,2,4]triazolo[1,5- a]pyrimidines, in which the trichloromethyl group is either maintained or eliminated from the product by simply controlling the reaction medium, is reported. These enones react with 3-amino-1H-1,2,4-triazoles under acidic conditions to furnish exclusively 7-(trichloromethyl)- [1,2,4]triazolo[1,5-a]pyrimidines, whereas under basic conditions [1,2,4]triazolo[1,5-a]pyrimidin-5/7(1H)-ones are obtained with elimination of the trichloromethyl group. The regioselectivity of the reactions performed under basic conditions is highly influenced by the substituents present in the starting enones. Twenty-one examples are synthesized using these two methodologies, with yields of up to 86%. [ABSTRACT FROM AUTHOR]

5-Bromo-1,1,1-trifluoro-4-methoxypent-3-en-2-one was used as an efficient precursor for the synthesis of a new series of (1,2,3-triazol-1-yl)methyl-pyrimidine biheterocycles. For this stepwise synthesis, the 5-bromo-1,1,1-trifluoro-4-methoxypent-3-en-2-one was first converted into 5-azido-1,1,1-trifluoro-4-methoxypent-3-en-2-one through a nucleophilic substitution of the bromine by an azide group. This was then followed by an azide-alkyne cycloaddition reaction (click chemistry) to give the key intermediate 5-[4-alkyl(aryl)-1H-1,2,3-triazol-1-yl]-1,1,1-trifluoro-4-methoxypent-3-en-2-ones. These were cyclocondensed with 2-methylisothiourea sulfate to give a series of 2-(methylthio)-4-(1,2,3-triazol-1-yl)methyl-6-(trifluoromethyl)pyrimidines. Additionally, the 2-methylthiopyrimidine products were used to prepare a new series of 2-amino-4-(1,2,3-triazol-1-yl)methyl-6-(trifluoromethyl)pyrimidines. [ABSTRACT FROM AUTHOR]

This study reports a simple and highly regioselective synthesis of a new series of 3,6-disubstituted 2-(methylsulfanyl)pyrimidin- 4(3H)-ones, in which the 6-substituents are methyl or aryl groups and the 3-substituents are alkyl, allyl, phenyl, benzyl, or 2-phenylethyl groups. The products are obtained in good yields by cyclocondensation of the appropriate 4-substituted 4-methoxy-1,1,1-trichloroalk-3-en-2- ones with nonsymmetric 1-substituted 2-methylisothiourea sulfates under mild basic conditions. [ABSTRACT FROM AUTHOR]

This study reports a simple, fast, and efficient method for the synthesis of a new series of 1-arylethyl-2-arylethylamino-5-trifluoroacetyl-1,2,3,4-tetrahydropyridines and related compounds from the reaction of 2-alkoxy-5-trifluoroacetyl-3,4-dihydro-2 H-pyrans with 2-arylethanamines and related 2-ethanamines. The desired tetrahydropyridines were obtained in excellent yields (90-98%), through a reaction that can be described as an AAB′ three-component reaction protocol following an ANRORC-type mechanism. [ABSTRACT FROM AUTHOR]