Das Joyee, Das Eshani, Jana Saibal, Addy Partha Sarathi, Anoop Anakuthil, Basak Amit
Department of Chemistry, Indian Institute of Technology Kharagpur , Kharagpur 721 302, India.
J Org Chem. 2016 Jan 15;81(2):450-7. doi: 10.1021/acs.joc.5b02246. Epub 2015 Dec 28.
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.
芳基或乙烯基取代的双炔丙基醚在碱处理下通常通过加勒特 - 布雷弗曼（GB）环化途径形成酞嗪。与这种常见途径大不相同的是，一些炔丙基臂之一末端带有2 - 四氢吡喃氧基甲基或乙氧基甲基的芳基/乙烯基双炔丙基醚在碱处理时显示遵循分子内1,5 - H迁移的替代途径。该反应以良好的产率导致形成了在合成及生物学上都很重要的3,4 - 二取代呋喃衍生物。溶液（CDCl₃）中最初形成的E异构体缓慢异构化为Z异构体，表明后者具有更高的稳定性。还评估了影响1,5 - H迁移和GB重排之间相互作用的因素，并且基于密度泛函理论（DFT）的计算研究支持了这些结果。
