Synthese von optisch aktiven, natürlichen Carotinoiden und strukturell verwandten Naturprodukten. II. Synthese von (3 S, 3′ S )‐Astaxanthin

Synthesis of optically active natural carotenoids and structurally related compounds. II. Synthesis of (3 S , 3′ S )‐astaxanthin The syntheses of rac. astaxanthin, (3 S , 3′ S )‐astaxanthin ( 1 ), its 15‐ cis isomer ( 21 ), its diacetate ( 22 ), and of (3 S , 3′ S )‐15, 15′‐didehydroastaxanthin ( 20 ) are reported.