Synthesis of Pyrazolo[5,1-a]isoindoles and Pyrazolo[5,1-a]isoindole-3-carboxamides through One-Pot Cascade Reactions of 1-(2-Bromophenyl)buta-2,3-dien-1-ones with Isocyanide and Hydrazin

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• 作者：Miaomiao Tian ; Yan He ; Xinying Zhang ; Xuesen Fan
• 刊名：Journal of Organic Chemistry
• 出版年：2015
• 出版时间：August 7, 2015
• 年：2015
• 卷：80
• 期：15
• 页码：7447-7455
• 全文大小：558K
• ISSN：1520-6904

文摘

A novel and efficient method for the construction of the pyrazolo[5,1-a]isoindole scaffold via a one-pot three-component cascade reaction of 1-(2-bromophenyl)buta-2,3-dien-1-one with hydrazine and isocyanide promoted by a Pd catalyst is described. This cascade process proceeds through initial condensation of the allenic ketone with hydrazine followed by Pd-catalyzed isocyanide insertion into the C鈥揃r bond and intramolecular C鈥揘 bond formation. Interestingly, when acetohydrazide was used in place of hydrazine, a more sophisticated procedure involving condensation, isocyanide insertion into C鈥揌 and C鈥揃r bonds, deacetylation, and formation of C鈥揅, C鈥揙, and C鈥揘 bonds occurred to afford pyrazolo[5,1-a]isoindole-3-carboxamides with good efficiency.