Synthesen von optisch aktiven Carotinoiden mit einer (R)‐4‐Hydroxy‐β‐Endgruppe

Abstract

Synthesis of Optically Active Carotenoids with (R)‐4‐Hydroxy β‐End Groups We describe the synthesis of optically active iso‐β‐kryptoxanthin (12; (R)‐β,β‐caroten‐4‐ol), iso‐α‐kryptoxanthins 14 ((4R,6′RS)‐β,ε‐caroten‐4‐ol) and 16 ((4R,6′R)‐β,ε‐caroten‐4‐ol), 4′‐hydroxyechinenone (18; (R)‐4′‐hydroxy‐β,β‐caroten‐4‐one), and isorubixanthin (20; (R)‐β,ω,‐caroten‐4‐ol), their 400‐MHz‐1H‐NMR spectra, CD spectra and HPLC behaviour.

Functions, Therapeutic Applications, and Synthesis of Retinoids and Carotenoids

“…Alternatively, central reagents with differentiated end groups, which have a protected aldehyde at one terminus and a phosphonium salt at the other, allow one to perform conjunctive Wittig chemistry iteratively (Schemes and ). The application of this tactic has led to the preparation of nonsymmetrical carotenoids, such as capsorubin ( 633 ), capsanthin-3,6-epoxide ( 712 ), and (3 R ,3′ S ,5′ R )-capsanthin ( 555 ) using the dioxolane phosphonium salt 711 (Scheme ), and of 4-hydroxy-α-carotene ( 714 ), isocryptoxanthin ( 715 ), thermozeaxanthin-15 ( 716a ) and thermocryptoxanthin-15 ( 716b ), (3 R )-triophaxanthin ( 717 ), cucurbitaxanthin A ( 719 ), cyclovioloxanthin ( 718 ), (3 R ,3′ S )-crassostreaxanthin B ( 720 ), and lutein ( 491 ), using the dimethylacetal Wittig salt 713 (Scheme ).…”

Total Synthesis of 1,2,5,6-Tetrahydro-2,6-cyclo-γ-carotene-1,5-diol, an Oxidation Product of γ-Carotene

“…The NMR data were in agreement with literature values. 25 (E)-16 1 Epoxy-3,7,11-trimethyldodeca-2,4,10-trienenitrile (17) NaH (60% suspension in mineral oil, 0.80 g, 20 mmol) was washed with hexane (3 × 5 mL) under argon. Anhydrous THF (5 mL) was added, and the mixture was cooled to -8 °C.…”

“…The protected C 10 -Wittig salt 12 is readily accessible according to published methods. 22,23 Although application of 12 in the synthesis of unsymmetrical carotenoids with sensitive end-groups has been well documented in the literature, [23][24][25] this building block has not been employed in the synthesis of 8, γ-carotene (3), or their precursors.…”

“…The preparation of 16 was accomplished in 68% overall yield in two steps according to a published procedure. 25 Horner-Wadsworth-Emmons reaction of diethyl cyanomethylphosphonate with chloroacetone gave (E/Z)-4chloro-3-methylbut-2-enenitrile (15) in 92% yield after column chromatography. In an Arbuzov reaction, nitrile 15 was then allowed to react with triethyl phosphite to afford 16 (E/Z = 1.1:1.0) in 74% isolated yield after distillation.…”

Carotenoids and polyterpenoids

“…30 Trace amounts of y-ionylideneacetic acid (34) were also present. The substituted y-ionylidene-ethanol structure (35) has been assigned to l a t i l ~b i n o l . ~~ The absolute structure of (+)strigol (36) has been determined by resolution of (k…”