GC-MS Analysis of beta-Carotene Ethenolysis Products and their Synthesis as Potentially Active Vitamin A Analogues.

beta-Carotene ethenolysis under promotion of well-defined ruthenium catalysts were examined as a novel method of synthesis of vitamin A derivatives. Efficient reaction was promoted by the second-generation Hoveyda catalyst. The products of ethenolysis in positions C15-C15', C11-C12, and C9-C10 were detected, but cleavage of the C11-C12 double bond predominated. Even better regioselectivity at this position was observed for cross-metathesis between beta-carotene and functionalized alkenes.