- Bacterial Carotenoids. 51. Chirality and Chiroptical Properties of (2S)-2-Isopentenyl-3,4-dehydrorhodopin (C.p. 482) and Related C45-Carotenoids
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Dehydration of C.p. 482 (2-isopentenyl-3,4-dehydrorhodopin; 2-(3-methyl-2-butenyl)-3,4-didehydro-1,2-dihyro-ψ,ψ-caroten-1-ol) with POCl3 provided a tert chloride, a conjugated and a non-conjugated anhydro product in varying yields depending on reaction conditions.Chiroptical propeties of C.p. 482 and its trimethylsilyl ether were considered.The 2S-chrirality of C.p. 482 was demonstrated by chiroptical comparison of its non-conjugated anhydro derivative with the same (2S)-carotenoid, here prepared by total synthesis.The dehydration to the non-conjugated anhydro derivative only slightly modified the CD curve but reduced Δε values significantly.For futher chiroptical studies (2'S)-2'-(3-methyl-2-butenyl)-1',16',3',4'-tetradehydro-1',2'-dihydro-β,ψ-carotene was synthesized.The 2'-isopentenyl substituent had a similar influence on the Cotton effects of the monochiral monocyclic C45-, the monochiral aliphatic C45- and the homodichiral aliphatic C50-carotenes considered.
- Andrewes, Arthur G.,Borch, Gunner,Liaaen-Jensen, Synnoeve
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p. 871 - 876
(2007/10/02)
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