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

Technical Procedures for the Synthesis of Carotenoids and Related Compounds from 6‐Oxo‐isophorone. VII. Synthesis of Rhodoxanthin and (3RS,3RS)‐Zeaxanthin from the C15‐Ring Component1 An efficient 7‐step synthesis of (3RS,3RS)‐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.