Technische Verfahren zur Synthese von Carotinoiden und verwandten Verbindungen aus 6‐Oxo‐isophoron. VII. Synthese von Rhodoxanthin und (3<i>RS</i>,3<i>RS</i>)‐Zeaxanthin aus der C₁₅‐Ringkomponente

Abstract

Technical Procedures for the Synthesis of Carotenoids and Related Compounds from 6‐Oxo‐isophorone. VII. Synthesis of Rhodoxanthin and (3 RS ,3 RS )‐Zeaxanthin from the C 15 ‐Ring Component 1 An efficient 7‐step synthesis of (3 RS ,3 RS )‐zeaxanthin ( 3 ) in 20% overall yield starting from 6‐oxo‐isophorone ( 7 ) is described. Intermediates are 6,6′‐dihydro‐rhodoxanthin ( 4 ) and rhodoxanthin ( 1 ), which are now accessible in 4 and 5 steps, and 45 and 25% overall yield, respectively. Novel methods for the simultaneous removal of the hydroxy group and the partial reduction of the triple bond of a monoalkynylated 1,4‐dioxo‐2‐ene system have been developed.