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Photo-reorganization of 3-alkoxy-6-chloro-2-(thiophen-3-yl)-4H-chromen-4-ones: Regioselective cyclization via γ-hydrogen abstraction

Paper ID Volume ID Publish Year Pages File Format Full-Text
28763 44090 2011 10 PDF Available
Title
Photo-reorganization of 3-alkoxy-6-chloro-2-(thiophen-3-yl)-4H-chromen-4-ones: Regioselective cyclization via γ-hydrogen abstraction
Abstract

Regioselective photocyclization of 3-alkoxy-6-chloro-4H-chromen-4-ones bearing thiophen-3-yl moiety at 2-position has been described. These chromenones on irradiation by the pyrex filtered UV-light produced a diverse array of novel angular tetracyclic photoproducts. Of these, mostly the cyclic dihydro and dehydrogenated photoproducts had the gem-dihydro functionality and exocyclic double bonds onto the fused pyran ring respectively, which is unprecedent in these chromenones.

Graphical abstractThe 1,4-biradicals generated through the Norrish type-II process in 3-alkoxy/allyloxy-2-(thiophen-3-yl)chromenones produced a diverse array of the novel dihydro and dehydrogenated angular tetracyclic photoproducts. Most of these products originated from the Dewar thiophene type intermediate generated in situ.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Regioselective photocyclization of thienylchromenones. ► Novel photoproducts having gem-dihydro functionality. ► Intermediacy of Dewar thiophene type moiety. ► [1,7]-H shift.

Keywords
Photoirradiation; Thienylchromenones; Cyclization reaction; 1,7-H shift
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Photo-reorganization of 3-alkoxy-6-chloro-2-(thiophen-3-yl)-4H-chromen-4-ones: Regioselective cyclization via γ-hydrogen abstraction
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 220, Issues 2–3, 20 May 2011, Pages 124–133
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
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Price was $35.95
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Price after discount Only $4.95
100% Money Back Guarantee
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