A scalable approach to diaminopyrazoles using flow chemistry
摘要:
This Letter reports on how the combination of microwave and continuous flow chemistry facilitated the convenient preparation of aminopyrazoles from commercial aryl halides. The method was applied to a variety of substrates with good to excellent yields and further extended toward the complete flow synthesis of 5,7-dimethyl-3-phenylpyrazolo[1,5-a]pyrimidin-2-amine. (c) 2012 Elsevier Ltd. All rights reserved.
A general and efficient synthesis of 4-substituted-1H-pyrazole-3,5-diamines was developed to access derivatives with an aryl, heteroaryl, or styryl group, which are otherwise relatively difficult to prepare. The first step is based on the Suzuki–Miyaura cross-coupling reaction utilizing the XPhos Pd G2 precatalyst. The coupling reactions of 4-bromo-3,5-dinitro-1H-pyrazole with the electron-rich/deficient