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Photochemical Reactions. 128 th Communication . Isolation of a Thermally Labile 2,8‐Dioxabicyclo[3.2.1]oct‐3‐ene Intermediate on Photolysis of 3,4: 5,6‐Diepoxy‐5,6‐dihydro‐β‐ionone
Author(s) -
Bischofberger Norbert,
Frei Bruno,
Jeger Oskar
Publication year - 1983
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.19830660409
Subject(s) - chemistry , photodissociation , ene reaction , yield (engineering) , photochemistry , medicinal chemistry , materials science , metallurgy
Photolysis (λ = 254 mm, THF) of the diepoxyenone ( E )‐ 1 at −78° leads to the 2,8‐dioxabicyclo[3.2.1]oct‐3‐ene intermediate 3 (51%). At ambient temperature 3 undergoes an unexpectedly rapid electrocyclic opening to the triketone 2 in quantitative yield. Compound 3 seems likely to be the intermediate in the acid‐catalyzed rearrangement of ( E )‐ 1 → 18 also.