I2-Catalyzed Multicomponent Reactions for Accessing Densely Functionalized Pyrazolo[1,5-a]pyrimidines and Their Disulphenylated Derivatives

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• 作者：Jun Sun ; Jiang-Kai Qiu ; Bo Jiang ; Wen-Juan Hao ; Cheng Guo ; Shu-Jiang Tu
• 刊名：Journal of Organic Chemistry
• 出版年：2016
• 出版时间：April 15, 2016
• 年：2016
• 卷：81
• 期：8
• 页码：3321-3328
• 全文大小：460K
• 年卷期：0
• ISSN：1520-6904

文摘

New I₂-catalyzed multicomponent bicyclization reactions of β-ketonitriles with sulfonyl hydrazides have been established, providing a direct and metal-free access toward unreported pyrazolo[1,5-a]pyrimidin-4-ium sulfonates. The latter could be quantitatively converted into densely functionalized pyrazolo[1,5-a]pyrimidines in the presence of bases. Using sulfonyl hydrazides as a sulfenylating agent, the resulting pyrazolo[1,5-a]pyrimidines enabled I₂-catalyzed unprecedented disulphenylations to access fully substituted pyrazolo[1,5-a]pyrimidines through direct C(sp²)–H bond bifunctionalization.