- Novel synthesis of degradation products of carotenoids, megastigmatrienone analogues and blumenol-A
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Synthesis of 4-alkylidene-3,5,5-trimethylcyclohex-2-enones 7 has been achieved utilising 1,4-conjugate dehydrobromination of allylic bromides 5 as a key step. This chemical transformation is applied to the synthesis of degradation products of carotenoids: megastigmatrienones 7e/1-4,4-methylene-3,5,5-trimethylcyclohex-2-enone 7a, 4-(3-hydroxybutylidene)-3,5,5-trimethylcyclohex-2-enone 9,1,3,7,7-tetramethyl-2-oxabicyclo[4.4.0]dec-5-en-9-one 10a-b and 3,4,7,8-tetrahydro-4,4,7-trimethylnaphthalen-2(6H)-one 15. A novel photoisomerisation of 4-[(Z)-3-acetoxybut-2-enyl]-4-hydroxy-3,5,5-trimethylcyclohex-2-enone 19 to 4-[(E)-3-acetoxybut-2-enyl]-4-hydroxy-3,5,5-trimethylcyclohex-2-enone 20 enables us to synthesise blumenol-A 21.
- Ito, Nobuhiko,Etoh, Takeaki,Hagiwara, Hisahiro,Kato, Michiharu
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p. 1571 - 1579
(2007/10/03)
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- Process for the manufacture of 4-(2-butenylidene)-3,5,5-trimethyl-2-cyclohexen-1-one
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A method for the manufacture of the four geometric isomers of 4(2-butenylidene)-3,5,5-trimethyl-2-cyclohexen-1-one is provided. The process comprises pyrolyzing a compound of the formula STR1 wherein R represents lower-alkyl-oxycarbonyl, aryl-oxycarbonyl, or, preferably, lower-alkanoyl, benzoyl or substituted benzoyl.
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- New Synthesis of Megastigma-4,6,8-trien-3-ones, 3-Hydroxy-β-ionol, 3-Hydroxy-β-ionone, 5,6-Epoxy-3-hydroxy-β-ionol, and 3-Oxo-α-ionol
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The Lewis acid-catalyzed reaction of 1-trimethylsiloxy-1,3-cyclohexadienes with aldehydes and trialkyl orthoformates afforded the corresponding 4-substituted 2-cyclohexenones.A new reaction of 2,4,6-trienones with m-chloroperbenzoic acid followed by the reduction with zinc in acetic acid gave 7-hydroxy-3,5-dienones.Utilizing these efficient reactions, megastigma-4,6,8-trien-3-ones, 3-hydroxy-β-ionol, 3-hydroxy-β-ionone, 5,6-epoxy-3-hydroxy-β-ionol, and 3-oxo-α-ionol were successfully synthesized.
- Takazawa, Osamu,Tamura, Hiroshi,Kogami, Kunio,Hayashi, Kazuo
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p. 1907 - 1911
(2007/10/02)
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