Oxo-a-Tocopherol

4-Oxo-a-tocopherol (55) proved to be a very interesting compound with regard to forming various intermediate tautomeric and quinoid structures. It undergoes an intriguing rearrangement of its skeleton under involvement of different o-QM structures. The 4-oxo-compound was prepared from 3,4-dehydro-a-tocopheryl acetate via its bromohydrin, which was treated with ZnO to afford 4-oxo-a-tocopherol (55). 

FIGURE 6.39 Synthesis of 4-oxo-a-tocopherol (55) and its oxidative rearrangement into 

The ZnO was a very effective reagent as it caused dehydrobromination, simultaneous deacetylation, and tautomerization of the resulting enol intermediate.69 

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Chromanol, 2,5,7,8-tetramethyl-2-(4,8,12-trimethyl tridecyl)-. See DL-a-Tocopherol 6-Chromanol, 2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-, acetate. See dl-a-Tocopheryl acetate 2-Chromanone. See Dihydrocoumarin ChromaOne . See Urethane-acrylate resin Chromasisi 87H, Chromasist 1487A. See Sodium polynaphthalene sulfonate Chromate(5-), bis (2-((4,5-dihydro-3-methyl-1-(2-methyl-4-sulfophenyl)-5-oxo-1H-pyrazol-4-yl) azo)-4-sulfobenzoato(4-))-, tetrasodium hydrogen. See Acid yellow 54 Chromate(3-), bis (3-hydroxy-4-((2-hydroxy-1-naphthalenyl) azo)-7-nitro-1-naphthalenesulfonato (3-))-, disodium hydrogen. See Acid black 52 Chromate (2-), (5-chloro-3-((4,5-dihydro-3-methyl-5-oxo-1-(3-sulfophenyl)-1H-pyrazol-4-yl) azo)-2-hydroxybenzenesulfonato (4-)) hydroxy-, disodium. See Acid red 183 Chromate copper arsenate CAS 11125-95-4... 

A series of 14 retinoids, carotenoids, and tocopherols from very polar (e.g., all-rranj-4-oxo-retinoyl /J-glucuronide, all-rranj-4 oxo-retinoic acid, all-rrans-5,6-epox-yretinoic acid) to slightly polar (e.g., all-tranj-retinol, all-trans-retinoic acid) to nonpolar (e.g., all-fra 5-lycopene, all-rrans-jS-carotene) were resolved on a Micro-sorb-MV column (A = 330nm) using a 100/0->0/100 (at 15 min hold 19 min) (3/1 methanol/water with 10mM ammonium acetate)/(4/l methanol/chloroform) gradient [350]. 

Figure 4 Reversed-phase HPLC elution profiles of tocopherols (panel A), retinoids (B), and carotenoids (C) present in human plasma (200 pL). Blood was collected 3 h after an oral dose of retinoic acid. The chromatogram was obtained by use of gradient elution (Table 3). Peak identification 2, 4-oxo-retinoic acid 4, retinoyl P-glucuronide 7, retinoic acid 8, retinol 9, retinyl acetate (internal standard) 15, butylated hydroxy toluene 16, y-tocopherol 17, a-tocopherol 18, free bilirubin 19, lutein 20, zeaxanthin 21, 2, 3 -anhydrolutein 22, P-cryptoxanthin 23, lycopene 24, a-carotene 25, P-carotene. (From Ref. 73.)...

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