ChemInform Abstract: TECHNICAL PROCEDURES FOR THE SYNTHESIS OF CAROTENOIDS AND RELATED COMPOUNDS FROM 6‐OXOISOPHORONE. II. A NOVEL CONCEPT FOR THE SYNTHESIS OF (3RS,3′RS)‐ASTAXANTHIN

Synthesis of Astaxanthin from β‐Ionone. I. A Route to the Enantiomeric C15‐Wittig Salts by Chemical and Microbial Resolution of (±)‐3‐Acetoxy‐4‐oxo‐β‐ionone Racemic 3‐acetoxy‐4‐oxo‐β‐ionone (10) was synthesized from the industrially accessible intermediate β‐ionone (5). Resolution of 10 into its enantiomers was achieved via the corresponding diastereomeric camphanates and by microbial resolution. Site‐selective alkylation of racemic and of optically pure 3‐acyloxy‐4‐oxo‐β‐ionones with vinyl magnesium chloride at −70° furnished the corresponding 3‐acyloxy‐4‐oxo‐9‐vinyl‐β‐ionols which could be transformed to the Wittig salts 1, 3 and 4, respectively, following known procedures [1].

unclassified

“…24 verseift, die anschliessend iiber die nicht isolierten primaren Bromide in die C,5-Phosphoniumsalze 3 bzw. 4 [ 11 [28] umgewandelt wurden. Aus einer typischen Reaktionsfolge 15 + 3 wurde ausgehend von 99,Sproz.…”

unclassified

Synthese von Astaxanthin aus β‐Jonon. I. Erschliessung der enantiomeren C₁₅‐Wittigsalze durch chemische und mikrobiologische Racematspaltung von (±)‐3‐Acetoxy‐4‐oxo‐β‐jonon

Becher

Albrecht

Bernhard

et al. 1981

“…(3 1) and concentrated to a volume of 2.5 1, whereby the product began to crystallize. [30] (1 13.9 g, 0.65 mol) was slowly added to a well-stirred slurry of KOH powder (109.4 g, 1.95 mol) in THF (525 ml ) at 0". After 20 min, a soh.…”

Section: Experimental Partmentioning

confidence: 99%

“…BuLi (2.8 1,4.5 mol) was slowly added to a soh. of IPM-5 [24] [30] (4.7 mol) in THF (0.5 1) at -15O. To this mixture, the soh.…”

Section: Experimental Partmentioning

confidence: 99%

Technical Procedures for the Syntheses of Carotenoids and Related Compounds from 6‐Oxo‐isophorone: Syntheses of (3R,3′R)‐Zeaxanthin. Part I

Widmer

Soukup

Zell

et al. 1990

Dedicated to Dr. Otfo Isler on the occasion of his 80th birthday (23.1V.90) Starting from the readily available, optically active (4R)-4-hydroxy-2,2,6-trimethylcyclohexanone (I), a new technical synthesis of (3R,3'R)-zeaxanthin is described. According to a 2(C9 + C,) + C,, = C,, construction scheme, the ketone 1 was first transformed with (E)-3-methylpent-2-en-4-yn-l-o1(5) into a CIS-intermediate which,by a three-step sequence, could be converted into the known olefinic CI5-Wittig salt 4. Optimized conditions for the final Wittig reaction of4 with the Clo-dialdehyde 3 are discussed. Based on 1, the overall yield of the entire technical process is ca. 40 %.

“…Mit der von Pinnick und Mitarbeitern [22] beschriebenen Methode zur Oxidation ungesattigter Aldehyde rnit NaClO, konnte 3 in t-BuOH/H,O in Gegenwart von 2-Methylbut-2-en als C1-Fanger wesentlich einfacher in (+)-Abscisinslure iibergefuhrt werden (57% Ausbeute). Diese Methode eignete sich jedoch nicht zur direkten Uberfiihrung des Dihydroxy-aldehydes 10 in (+)- Abscisinsaure ((+)-1 [21]. (Vorsicht, starke H,-Entwicklung) und schliesslich auf 0" erwarmt.…”

unclassified

Synthese von (+)‐Abscisinsäure

Soukup

Lukac

Lohri

et al. 1989