{"title":"Construction of pyrazolo[1,5-<i>a</i>]pyrimidines and pyrimido[1,2-<i>b</i>]indazoles with calcium carbide as an alkyne source.","authors":"Xinjie You, Botao Wang, Fei Wen, Zheng Li","doi":"10.1039/d4ob00881b","DOIUrl":null,"url":null,"abstract":"<p><p>An efficient method for the construction of 5-arylpyrazolo[1,5-<i>a</i>]pyrimidines using calcium carbide as a solid alkyne source instead of flammable and explosive gaseous acetylene, pyrazole-3-amine and (hetero)aromatic aldehydes as starting materials in the presence of a copper mediator is described. Meanwhile, 2-arylpyrimido[1,2-<i>b</i>]indazoles are also synthesized under similar conditions using indazole-3-amine as a substitute for pyrazole-3-amine as a starting material. The method has salient features such as the use of an inexpensive and easy-to-handle alkyne source, commercially available substrates, wide functional group tolerance, a low-cost mediator, and simple workup procedures. This protocol can also be extended to gram-scale synthesis.</p>","PeriodicalId":96,"journal":{"name":"Organic & Biomolecular Chemistry","volume":null,"pages":null},"PeriodicalIF":2.9000,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Organic & Biomolecular Chemistry","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1039/d4ob00881b","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, ORGANIC","Score":null,"Total":0}
引用次数: 0
Abstract
An efficient method for the construction of 5-arylpyrazolo[1,5-a]pyrimidines using calcium carbide as a solid alkyne source instead of flammable and explosive gaseous acetylene, pyrazole-3-amine and (hetero)aromatic aldehydes as starting materials in the presence of a copper mediator is described. Meanwhile, 2-arylpyrimido[1,2-b]indazoles are also synthesized under similar conditions using indazole-3-amine as a substitute for pyrazole-3-amine as a starting material. The method has salient features such as the use of an inexpensive and easy-to-handle alkyne source, commercially available substrates, wide functional group tolerance, a low-cost mediator, and simple workup procedures. This protocol can also be extended to gram-scale synthesis.