Syntheses of the Enantiomeric Aleuriaxanthins. Detection of a Predominant (Z)‐Aleuriaxanthin inAleuriaThe enantiomeric C10‐building blocks9((+)‐(2E, 6 R)‐6, 7‐dihydroxy‐3, 7‐di methyl‐2‐octen‐l‐yl acetate) andent‐9, and11((+)‐(2E, 6R)‐3, 7‐dimethyl‐2, 7‐octadien‐l, 6‐diyl diacetate) andent‐11, prepared from the optically active epoxy‐geraniols7andent‐7, respectively, have been used for the syntheses of (2′R)‐aleuriaxanthin (1) and (2′S)‐aleuriaxanthin (ent‐1).At room temperature aleuriaxanthin exhibits no significant CD. nor ORD. However, at −180° a very distinct CD. was observed, which in the UV. range showed a surprising resemblance to that of (3R, 3′R)‐zeaxanthin. By direct comparison of1with aleuriaxanthin isolated fromAleuria aurantia[2], the (2′R)‐chirality assigned to the latter byLiaaen‐Jensen et al.[5] is confirmed.HPLC. separation of the mixture of carotenoids fromAleuriashows the presence