Tsukida K, Saiki K
J Nutr Sci Vitaminol (Tokyo). 1983 Apr;29(2):111-22. doi: 10.3177/jnsv.29.111.
Thermal isomerization of synthetic all-(E)-beta-carotene yielded a multi-component mixture composed of more than sixteen (Z)-beta-carotenes and two thermo-cyclized isomers. They were separated and purified by high-performance liquid chromatography. Ten of these were characterized by spectroscopic methods as four mono-(Z)-, five di-(Z)-, and one tri-(Z)-beta-carotenes; the 7-(Z)-, 9-(Z)-, 13-(Z)-, 15-(Z)-, 9.13-(Z)-, 9.15-(Z)-, 9.13'-(Z)-, 13.15-(Z)-, 7.13'-(Z)-, and 9.9'.13-(Z)-isomers were included. Stereochemistry of six additional (Z)-isomers obtained is, as yet, unknown, though one of them might have the 9.9'-(Z)-geometry in the molecule. This is the first report on the formation and identification of the 'sterically hindered' 7-(Z)-isomers as well as the (5 leads to 10)-thermo-cyclized products in the field of alicyclic carotenoids.
合成的全（E）-β-胡萝卜素的热异构化产生了一种多组分混合物，该混合物由十六种以上的（Z）-β-胡萝卜素和两种热环化异构体组成。它们通过高效液相色谱法进行分离和纯化。其中十种通过光谱方法表征为四种单（Z）-、五种二（Z）-和一种三（Z）-β-胡萝卜素；包括7-（Z）-、9-（Z）-、13-（Z）-、15-（Z）-、9,13-（Z）-、9,15-（Z）-、9,13'-（Z）-、13,15-（Z）-、7,13'-（Z）-和9,9',13-（Z）-异构体。尽管其中一种可能在分子中具有9,9'-（Z）-构型，但所获得的另外六种（Z）-异构体的立体化学尚未可知。这是关于脂环族类胡萝卜素领域中“空间位阻”7-（Z）-异构体以及（5至10）-热环化产物的形成和鉴定的首次报道。
