Premium
Photochemical reactions. 134 th Communication . Photochemistry of 5,6‐epoxy‐5,6‐dihydro‐3,4‐methano‐β‐ionone: Influence of a cyclopropane ring on the reactivity of an ylide intermediate
Author(s) -
Bischofberger Norbert,
Frei Bruno,
Jeger Oskar
Publication year - 1984
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.19840670117
Subject(s) - chemistry , ylide , photochemistry , isomerization , diastereomer , reactivity (psychology) , cyclopropane , flash photolysis , quenching (fluorescence) , photodissociation , ring (chemistry) , epoxide , medicinal chemistry , stereochemistry , fluorescence , organic chemistry , kinetics , reaction rate constant , alternative medicine , pathology , quantum mechanics , catalysis , medicine , physics
On 1 n,π*‐excitation(λ > 347 nm), the diastereomeric methanoepoxyenones ( E )‐ 6 undergo isomerization via C,O‐cleavage of the oxirane leading to diastereomeric photoproducts (( E )‐ 5 →( E / Z )‐ 13 and 14 ; ( E )‐ 6 →( E / Z )‐ 16 and 17 ). On 1 π,π*‐excitation (λ = 254 nm) of either ( E )‐ 5 ) or ( E ‐ 6 the photoproducts 9, 10 and 11 are formed. By laser flash photolysis (λ = 265 nm) the ylide intermediate 3 was detected, with a lifetime of 10 μs in MeCN at ambient temperature. Stern‐Volmer analysis of the ylide quenching by MeOH disclosed that compounds 9 and 10 , but not 11 , arise from the ylide intermediate e .