The stereochemistry of dehydro-[Beta]-carotene. Studies on the interaction of some carotenoids with boron trifluoride and N-bromosuccinimide. Provitamin A activity of a C41-carotenoid
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An extensive study of the stereoisomerization of dehydro-[Beta]-carotene is presented. Two of the cis isomers have been isolated in crystalline form and described. The nature of "isocarotene" has been clarified.
Treatment of [Beta]-carotene with boron trifluoride under defined conditions leads chiefly either to its stereoisomerization or chemical conversion. Two of the several conversion products have been crystallized; a third, exhibiting strong fluorescence in ultraviolet light is also described.
Three new carotenoids, termed isocryptoxanthin, isocryptoxanthin methyl ether, and dimethoxy-[Beta]-carotene, formed by the addition of water or methanol to dehydro-[Beta]-carotene in the presence of boron trifluoride are described. The structures of the first two compounds have been determined; the location of the substituent groups in the third is, at present, uncertain.
Dehydro-[Beta]-carotene, bisdehydro-[Beta]-carotene, and anhydroeschscholtzxanthin have been isolated from the end products of the reaction of [Beta]-carotene with N-bromosuccinimide. Bisdehydro-[Beta]-carotene is a new carotenoid whose probable structure is discussed.
The considerable provitamin A potency of 16,16'-homo-[Beta]-carotene is discussed from the standpoint of its novel structural features
