Total Synthesis of Loroxanthin.

The first total synthesis of loroxanthin () was accomplished by Horner-Wadsworth-Emmons reaction of C-apocarotenal having a silyl-protected 19-hydroxy moiety with C-phosphonate bearing a silyl-protected 3-hydroxy-ε-end group. Preparation of apocarotenal was achieved via Stille coupling reaction of alkenyl iodide with alkenyl stananne , whereas phosphonate was prepared through treatment of ally alcohol with triethyl phosphite and ZnI. The ally alcohol was derived from the known (3,6)-3-hydroxy C-aldehyde which was obtained by direct optical resolution of racemate using a semi-preparative chiral HPLC column.