Sikdar P, Choudhuri T, Paul S, Das S, Bagdi AK. K
2S
2O
8-Promoted Consecutive Tandem Cyclization/Oxidative Halogenation: Access to 3-Halo-Pyrazolo[1,5-
a]pyrimidines.
ACS OMEGA 2023;
8:23851-23859. [PMID:
37426282 PMCID:
PMC10323951 DOI:
10.1021/acsomega.3c02270]
[Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 06/09/2023] [Indexed: 07/11/2023]
Abstract
A one-pot methodology has been developed to synthesize 3-halo-pyrazolo[1,5-a]pyrimidine derivatives through the three-component reaction of amino pyrazoles, enaminones (or chalcone), and sodium halides. The use of easily accessible 1,3-biselectrophilic reagents like enaminones and chalcone offers a straightforward approach for the synthesis of 3-halo-pyrazolo[1,5-a]pyrimidines. The reaction proceeded through a cyclocondensation reaction between amino pyrazoles with enaminones/chalcone in the presence of K2S2O8 followed by oxidative halogenations by NaX-K2S2O8. Mild and environmentally benign reaction conditions, wide functional group tolerance, and scalability of the reaction are the attractive facet of this protocol. The combination of NaX-K2S2O8 is also beneficial for the direct oxidative halogenations of pyrazolo[1,5-a]pyrimidines in water.
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