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Zur Photochemie des Iso‐methyl‐α, ( E )‐jonons
Author(s) -
Becker Josef,
Ehrenfreund Josef,
Jeger Oskar,
Ohloff Günther,
Wolf Hans Richard
Publication year - 1974
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.19740570847
Subject(s) - chemistry , photoisomerization , isomerization , epoxide , bicyclic molecule , ionone , irradiation , ether , stereochemistry , photochemistry , organic chemistry , catalysis , physics , nuclear physics
UV.‐irradiation of iso‐methyl‐α, ( E )‐ionone ( 4 ) in neutral solvents yields iso‐methyl‐α, ( Z )‐ionone ( 5 ), the bicyclic ether 6 and the epoxide 7 by a sequence of successive photoisomerizations. The steps leading to des‐methyl homologues of 6 and 7 do not occur on irradiation of α, ( E )‐ionone ( 1 ) [10]. The reversible isomerization 4 ⇄ 5 is followed by the irreversible photoprocess 5 → 6 and the final transformation 6 → 7 . Irradiation of iso‐methyl‐α, ( E )‐ionone ( 4 ) in acidic or basic solvents leads to a deep change in the type of products and gives the isomeric ketones 9 and 10 in high yields. A tentative mechanism for the photoisomerization steps 5 → 6, 6 → 7 and 5 → 9 + 10 is proposed.