Synthese von Carotinoiden mit hydroxylierter Methylgruppe an der Polyenkette mit Hilfe von Vinyl‐Anionen ( Shapiro ‐Reaktion)

Syntheses of Hydroxymethyl‐carotenoids Using Vinyl‐Anions Generated by the Shapiro ‐Reaction A versatile synthesis of hydroxymethyl‐carotenoids with β‐ or ϵ‐end groups is presented. It makes use of the reactive vinyl anions prepared by the Shapiro ‐reaction from (phenylsulfonyl)hydrazones of polyenones and their smooth 1,2‐addition to polyenals. Thus, e.g. (3 R ,6′ R )‐β, ϵ‐carotene‐3, 19‐diol ( 72 ), an optically active model compound structurally very close to loroxanthin ( 1 ), has been synthesized.