title: 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.
abstract: 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.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Kharagpur , Kharagpur 721 302, India.
authors.forename: Joyee
authors.initials: J
authors.lastname: Das
authors.affiliation: Department of Chemistry, Indian Institute of Technology Kharagpur , Kharagpur 721 302, India.
authors.forename: Eshani
authors.initials: E
authors.lastname: Das
authors.affiliation: Department of Chemistry, Indian Institute of Technology Kharagpur , Kharagpur 721 302, India.
authors.forename: Saibal
authors.initials: S
authors.lastname: Jana
authors.affiliation: Department of Chemistry, Indian Institute of Technology Kharagpur , Kharagpur 721 302, India.
authors.forename: Partha Sarathi
authors.initials: PS
authors.lastname: Addy
authors.affiliation: Department of Chemistry, Indian Institute of Technology Kharagpur , Kharagpur 721 302, India.
authors.forename: Anakuthil
authors.initials: A
authors.lastname: Anoop
authors.affiliation: Department of Chemistry, Indian Institute of Technology Kharagpur , Kharagpur 721 302, India.
authors.forename: Amit
authors.initials: A
authors.lastname: Basak