4-Dimethylamino Pyridine-Promoted One-Pot Three-Component Regioselective Synthesis of Highly Functionalized 4H-Thiopyrans via Heteroannulation of 尾-Oxodithioesters
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- 作者：Rajiv Kumar Verma ; Girijesh Kumar Verma ; Gaurav Shukla ; Anugula Nagaraju ; Maya Shankar Singh
- 刊名：ACS Combinatorial Science
- 出版年：2012
- 出版时间：March 12, 2012
- 年：2012
- 卷：14
- 期：3
- 页码：224-230
- 全文大小：304K
- 年卷期：v.14,no.3(March 12, 2012)
- ISSN：2156-8944
文摘
A highly convergent and regioselective heteroannulation protocol for the synthesis of hitherto unreported highly substituted 2-amino-4-(aryl/alkyl)-5-(aroyl/heteroaroyl)-3-(cyano/carboalkoxy)-6-methylthio-4H-thiopyran derivatives has been developed. This one-pot three-component domino coupling of 尾-oxodithioesters, aldehydes, and malononitrile/ethyl or methyl cyanoacetate is promoted by 4-dimethylamino pyridine (DMAP) in solvent (dichloromethane (DCM)) as well as under solvent-free conditions. Systematic optimization of reaction parameters identified that the three-component coupling (3CC) protocol is tolerant to a wide array of functionality providing densely functionalized 4H-thiopyrans in excellent yields. The merit of this cascade Knoevenagel condensation/Michael addition/cyclization sequence is highlighted by its high atom-economy, excellent yields, and efficiency of producing three new bonds (two C鈥揅 and one C鈥揝) and one stereocenter in a single operation.