Synthesen von enantiomerenreinen Apoviolaxanthin-s�uren, -olen und -alen (Persicaxanthin, Sinensiaxanthin und ?-Citraurin-epoxid) und ihrer furanoiden Umlagerungsprodukte

Synthesis of Enantiomerically Pure Apoviolaxanthinoic Acids, Apoviolaxanthinols, and Apoviolaxanthinals (Including Persicaxanthin, Sinensiaxanthin, and β-Citraurin Epoxide) and of their Furanoid Rearrangement Products Starting from (1′S,2′R,4′S,2E,4E)-5-(1′,2′-epoxy-4′-hydroxy-2′,6′,6′-trimethylcyclohexy1)-3-methy1-2,4-pentadienal (3), a recently described synthon [6], a full range of C20-, C25-, C27-, and C30-polyenic acids, alcohols, and aldehydes and their (8R)- and (8S)-diastereoisomeric furanoid rearrangement products was prepared. The synthetic C25-alcohols proved to be identical with persicaxanthin (= 12′-apoviolaxanthin-12′-ol) and perisicachromes (= 12′-apoauroxanthin-12′-ols) and the C27-alcohols analogously with sinensiaxanthin and sinensiachromes. A correlation between the sign of the Cotton effects in the CD spectra of 5,6-and 5,8-epoxides and their configuration at C(6) and C(8), respectively, was established.