Synthetic Versatility of β-Alkoxyvinyl Trichloromethyl Ketones for Obtaining [1,2,4]Triazolo[1,5-a]pyrimidines

• DOI: 10.1055/s-0037-1610191
• Publication Date: 2018-07-24T10:49:01Z
• Authors: Nilo Zanatta; Laura Souza; Josiane Santos; Mateus Mittersteiner; Valquiria Andrade; Marcio Lobo; Felipe Santos; Adailton Bortoluzzi; Helio Bonacorso; Marcos Martins
• Keywords: 01 natural sciences; 0104 chemical sciences

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%.