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Photochemische Reaktionen. 83. Mitteilung. Verbindungen der 3,4‐Dihydrojonon‐Reihe als Modelle zur Photochemie γ, δ‐ bzw. δ, ϵ‐ungesättigter Ketone und Aldehyde
Author(s) -
Zink Markus Peter,
Wolf Hans Richard,
Müller Ernst Peter,
Schweizer Wolfhard Bernd,
Jeger Oskar
Publication year - 1976
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.19760590105
Subject(s) - oxetane , chemistry , ketone , bicyclic molecule , intramolecular force , aldehyde , hydrogen atom abstraction , ether , photodissociation , intramolecular reaction , ionone , enone , stereochemistry , medicinal chemistry , photochemistry , organic chemistry , radical , catalysis
Compounds of the 3,4‐dihydro‐ionone series as models for the photochemistry of γ, δ‐ and δ,ϵ‐ unsaturated ketones and aldehydes . The photochemistry of γ, δ‐ and δ,ϵ‐unsaturated carbonyl compounds of the dihydro‐ionone series has been studied, with special attention to the investigation of oxetane formation versus hydrogen abstraction. UV.‐irradiation of the dihydro‐β‐ionone compounds with structure A ( 1 , 7 , 14 , 18 , 24 , 29 ) led to isomeric ethers with structures B ( 2 , 8 , 15 , 19 , 25 , 30 ), C ( 3 , 9 , 16 , 20 , 26 , 31 ) and D ( 4 , 21 , 27 ), isomeric bicyclic alcohols with structure E ( 5 , 10 , 17 , 22 , 28 ), and photoreduction products with structure F ( 6 , 11 , 12 , 13 ). Photolysis of dihydro‐γ‐ionone ( 32 ) gave a complex mixture containing fragmentation product 35 , hydrocarbon 36 , β‐ambrinol ( 34 ), oxetane 33 , as well as dihydro‐β‐ionone ( 1 ) and three of its photoproducts ( 2 , 3 , 5 ). The dihydro‐α‐ionone compounds 37 and 40 gave mixtures of fragmentation products and the oxetanes 38 and 41 . Irradiation of the side‐chain homologues 42 and 45 yielded 43 , which photo‐cyclizes to 44 . In contrast, 3 , 4 ‐dihydro‐3′,4′‐dehydro‐β‐ionone ( 46 ) gave merely the isomeric open‐chain triene‐ketone 47 . The structures assigned to the ethers 2 , 3 , 33 , 38 and to the alcohols 5 , 10 , 13 could be confirmed by chemical reactions and mutual interconversions. The structure of the ether 21 had to be established by X‐ray analysis, details of which are described. A novel intramolecular hydrogen transfer is involved in formation of ethers B . The photocyclization A → D probably proceeds by addition of the carbonyl‐C atom to the double bond ( A → h ), followed by methyl (1 → 2)‐shift ( h → i ). Process A → h may also be involved in formation of compounds of type C and E .