Regioselective Synthesis of Dihydrothiophene and Thiopyran Frameworks via Catalyst-Controlled Intramolecular C纬/C未鈥揝 Fusion of 伪-Allyl-尾鈥?oxodithioesters

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• 作者：Sushobhan Chowdhury ; Tanmoy Chanda ; Suvajit Koley ; Namrata Anand ; Maya Shankar Singh
• 刊名：Organic Letters
• 出版年：2014
• 出版时间：November 7, 2014
• 年：2014
• 卷：16
• 期：21
• 页码：5536-5539
• 全文大小：340K
• ISSN：1523-7052

文摘

A highly efficient and atom-economic dual reaction manifold has been developed to synthesize 4H-thiopyran and 4,5-dihydrothiophene frameworks via regioselective intramolecular C鈥揝 fusion of 伪-allyl-尾鈥?oxodithioesters. The ring size of the sulfur-heterocycles has been efficiently tuned by the use of two different catalytic systems. Palladium activates the C_未鈥揌 of the allyl termini and facilitates the intramolecular C_未鈥揝 coupling to furnish six-membered thiopyran skeletons exclusively. Conversely, the allylic double bond of the same substrate has been activated by BF₃路Et₂O to promote the C_纬鈥揝 cyclization leading to the formation of a five-membered dihydrothiophene nucleus.