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Photochemical reactions. 132 nd communication . Photochemistry of 5,6‐epoxy‐5,6‐dihydro‐7‐methyl‐β‐ionine: Influence of a methyl group at the enone side chain on the oxirane cleavage
Author(s) -
Siewnski Antoni,
Henggeler Barbara,
Wolf Hans Richard,
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.19840670115
Subject(s) - chemistry , conformational isomerism , enone , isomerization , photochemistry , photodissociation , methyl group , carbene , bond cleavage , excitation , stereochemistry , cleavage (geology) , group (periodic table) , organic chemistry , molecule , geotechnical engineering , fracture (geology) , engineering , catalysis , electrical engineering
1 n, π*‐Excitation of the γ,δ‐epoxy‐enone ( E )‐ 3 leads exclusively to the conformers ( Z )‐ 3A + B . On 1 π, π*‐excitation of ( E )‐ 3 , in addition to ( Z )‐ 3A + B , products 6–9 arising from a carbene intermediate e are formed. However, products of an isomerization via C(γ), O‐bond cleavage of the oxirane were not formed on either mode of excitation. On thermolysis, at 80° the conformer ( Z )‐ 3A is transformed into ( Z )‐ 3B , which on photolysis returns to ( Z )‐ 3A and ( E ) ‐3 . At 160°, however, ( Z ) ‐3B rearranges to the isomers 6, 10 and 11 .