Deep eutectic solvent mediated synthesis of thiomethyltriazolo[1,5-a]pyrimidines

作者：Martins Marcos A P^*; Paveglio Guilherme C; Munchen Taiana S; Meyer Alexandre R; Moreira Dayse N; Rodrigues Leticia V; Frizzo Clarissa P; Zanatta Nilo; Bonacorso Helio G; Melo Paola A; Krzyzaniak Sindy R

来源：Journal of Molecular Liquids, 2016, 223: 934-938.

DOI：10.1016/j.molliq.2016.08.031

• Deep eutectic solvent
• Triazolopyrimidines
• Catalysis
• Enaminones

Molecular solvents, ionic liquids, and choline chloride-based DES were evaluated for the synthesis of a methylthiotriazolo[1,5-a]pyrimidines series via the cyclocondensation reaction between 4-dimethylamino-1-aryl-3-alken-2-ones (RC(O)CH = CHNMe2, in which R = C6H5, 4-Me-C6H4, 4-OMe-C6H4, 4-F-C6H4, 4-Br-C6H4, 4-I-C6H4, Fur-2-yl, and Thien-2-yl) and 3-amino-5-methylthio-1H-1,2,4-triazole. The best result was obtained using ChCl with TsOH at a ratio of 1:2, and it drastically reduced the reaction time from 1.5 h to 5 min, with high regioselectivity and good yields (82-98%). Quantum chemical calculations helped to show the mechanism for high regioselectivity of the reaction. Up until now, ChCI:TsOH (1:2) has not been completely characterized and used as a catalyst in organic synthesis. Thus, it was fully characterized by NMR, DSC, TGA, and ICP-AES. The results showed that ChCI:TsOH (1:2) presents two forms that can act as catalyst: acid form (17%) and its conjugate base (83%).

• 出版日期2016-11