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

✍ Scribed by Milan Soukup; Erich Widmer; Theodor Lukáč

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: German
• Weight: 420 KB
• Volume: 73
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19900730412

✦ Synopsis

Abstract

Starting from the readily available, optically active (4__R__)‐hydroxy‐2,2,6‐trimethylcyclohexanone (2), a new technical synthesis of (3__R__,3′R)‐zeaxanthin is described. According to a completely new C~9~+C~2~+C~4~ = C~15~ scheme, the ketone 2 was protected, ethynylated with Li‐acetylide, and the C~11~‐intermediate 6 was acetylated, followed by dehydration. The product 10 was protected, deprotonated, and subsequently reacted with methyl vinyl ketone to provide the C~15~‐propargylate 13. Reduction in situ of 13 with Vitride yielded the olefinic C~15~‐alcohol 11 which was transformed into the known C~15~‐Wittig salt 3. A double Wittig reaction of this salt with the C~10~‐dialdehyde 4 afforded nature‐identical zeaxanthin (1).