Shifting the Reactivity of Bis-propargyl Ethers from Garratt–Braverman Cyclization Mode to 1,5-H Shift Pathway To Yield 3,4-Disubstituted Furans: A Combined Experimental and Computational Study

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• 作者：Joyee Das ; Eshani Das ; Saibal Jana ; Partha Sarathi Addy ; Anakuthil Anoop ; Amit Basak
• 刊名：Journal of Organic Chemistry
• 出版年：2016
• 出版时间：January 15, 2016
• 年：2016
• 卷：81
• 期：2
• 页码：450-457
• 全文大小：524K
• ISSN：1520-6904

文摘

Aryl or vinyl substituted bis-propargyl ethers upon base treatment generally form phthalans via the Garratt–Braverman (GB) cyclization pathway. In a major departure from this usual route, several aryl/vinyl bis-propargyl ethers with one of the acetylenic arms ending up with 2-tetrahydropyranyloxy methyl or ethoxy methyl have been shown to follow the alternative intramolecular 1,5-H shift pathway upon base treatment. The reaction has led to the formation of synthetically as well as biologically important 3,4-disubstituted furan derivatives in good yields. The initially formed E isomer in solution (CDCl₃) slowly isomerizes to the Z isomer, indicating greater stability of the latter. The factors affecting the interplay between the 1,5-H shift and GB rearrangement have also been evaluated, and the results are supported by DFT-based computational study.