作者:Bjart Frode Lutnaes、Jostein Krane、Synn�ve Liaaen-Jensen
DOI:10.1039/b410299a
日期:——
Previous work on carotenoid–iodine complexes is briefly reviewed. The formation of iodine complexes of β,β-carotene and of (3R,3′R)-β,β-carotene-3,3′-diol (zeaxanthin) has been studied by modern methods including UV/VIS/NIR, IR MS, EPR, ENDOR and NMR (1H, 1H–1H COSY, TOCSY, 2D ROESY, 1H–13C HSQC and 1H–13C HMBC) spectroscopy, and chemical reactions monitored by HPLC, TLC and spectral analysis (VIS, MS, 1H NMR). β,β-Carotene formed a solid complex C40H56
× 4I with iodine in hexane and a solvent complex with λmax 1010 nm in chlorinated solvents. Iodine was not covalently bound to the carotene. Spectroscopic and chemical evidence is consistent with the representation of the β,β-carotene–iodine complex containing iodine in a π complex with cationic/radical cationic properties. Extensive E/Z isomerisation was noted for all quenching products obtained in acetone, with thiosulfate, by dilution, or by reaction with nucleophile (MeOH). Key products obtained from the β,β-carotene–iodine complex were 4′,5′-didehydro-4,5′-retro-β,β-carotene (isocarotene) and 4-methoxy-β,β-carotene. The zeaxanthin–iodine complex was not suitable for a practical synthesis of (3S,3′S)-4′,5′-didehydro-4,5′-retro-β,β-carotene-3,3′-diol (eschscholtzxanthin).
本文简要回顾了以往有关类胡萝卜素-碘络合物的研究工作。通过现代方法,包括 UV/VIS/NIR、IR MS、EPR、ENDOR 和 NMR(1H、1H-1H COSY、TOCSY、2D ROESY、1H-13H COSY、TOCSY、2D ROESY),研究了 β、β-胡萝卜素和(3R,3′R)-β、β-胡萝卜素-3,3′-二醇(玉米黄质)碘络合物的形成、ENDOR、核磁共振(1H、1H-1H COSY、TOCSY、2D ROESY、1H-13C HSQC 和 1H-13C HMBC)光谱,并通过 HPLC、TLC 和光谱分析(VIS、MS、1H NMR)监测化学反应。β,β-胡萝卜素在正己烷中与碘形成固体络合物 C40H56 × 4I,在氯化溶剂中形成溶剂络合物,λmax 为 1010 nm。碘没有与胡萝卜素共价结合。光谱和化学证据表明,β,β-胡萝卜素-碘络合物中的碘是一种具有阳离子/激阳离子特性的 π 络合物。在丙酮、硫代硫酸钠、稀释或与亲核剂(MeOH)反应中得到的所有淬灭产物都具有广泛的 E/Z 异构化。β,β-胡萝卜素-碘复合物的主要产物是 4′,5′-二脱氢-4,5′-反式-β,β-胡萝卜素(异胡萝卜素)和 4-甲氧基-β,β-胡萝卜素。玉米黄质-碘络合物不适合实际合成 (3S,3′S)-4′,5′-二脱氢-4,5′-反式-β,β-胡萝卜素-3,3′-二醇(eschscholtzxanthin)。