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Photochemische Reaktionen 113. Mitteilung [1]. Zur Photospaltung konjugierter γ, δ‐Epoxyenone: UV.‐Bestrahlung von 5, 6‐Epoxy‐3,4‐didehydro‐5,6‐dihydro‐β‐jonon
Author(s) -
Murato Kazuo,
Wolf Hans Richard,
Jeger Oskar
Publication year - 1980
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19800630811
Subject(s) - chemistry , methanol , acetonitrile , cyclopropane , pentane , derivative (finance) , irradiation , acetal , photochemistry , conjugated system , medicinal chemistry , stereochemistry , organic chemistry , ring (chemistry) , physics , nuclear physics , financial economics , economics , polymer
The Photoinduced Cleavage of Conjugated γ, δ‐Epoxyenones: UV.‐Irradiation of 5,6‐Epoxy‐3, 4‐didehydro‐5,6‐dihydro‐β‐ionone On 1 n, π*‐excitation (λ ≥ 347 nm) in pentane or CClF 2 CFCl 2 ( E )‐ 1 is isomerized to the dihydrofurane ( E/Z )‐ 2 as well to the ethers 3 and 5. Besides these products the isomeric cyclopropane derivative ( E )‐ 4 and the acetal 6 are obtained in methanol. The detection of 6 indicates the formation of an intermediate ketoniumylide a which may give 6 by addition of methanol. − On 1 π, π*‐excitation (λ=254 nm) in acetonitrile‐ d 3 , CClF 2 CFCl 2 or pentane ( E )‐ 1 yields almost exclusively ( E )‐ 2. In methanol 6 is obtained in addition to ( E/Z )‐ 2 , but no ( E )‐ 4 and 5 is formed.