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Photochemical Reactions 151st Communication . Photo‐oxygenation of ( E )‐ and ( Z )‐7‐Methyl‐β‐ionone
Author(s) -
Nishio Takehiko,
Mathies Peter,
Job Kurt,
Frei Bruno,
Jeger Oskar
Publication year - 1989
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.19890720510
Subject(s) - chemistry , hemiacetal , chromophore , intramolecular force , singlet oxygen , ionone , photochemistry , stereochemistry , epoxide , peroxide , medicinal chemistry , oxygen , organic chemistry , catalysis
Photo‐oxygenation of ( E )‐7‐methyl‐β‐ionone (( E )− 1 ) and ( E )‐8‐methyl‐β‐ionone (( E )− 2 ) gave rise to the formation of the hydroperoxy‐enones ( E )− 10 and ( E )− 15 , respectively, which, in part, underwent intramolecular epoxidation to the hydroxy‐epoxy‐ketones 11 and 16 , respectively, The product distribution of the photo‐oxidation of (Z)− 1 shows a marked influence of the skewed ground‐state conformation of the dienone chromophore. Thus, singlet oxygen ( 1 O 2 ) was added to C(γ) of the dienone chromophore leading to the spirocyclic peroxy‐hemiacetal 12 and to the endoperoxide 13 . In addition, the tricyclic peroxide 14 was formed as a new type of product via primary addition of 1 O 2 to C(γ) of the dienone chromophore. The structure of 14 was established by X‐ray crystal‐structure analysis of the hemiacetal 22 .