Palladium-Catalyzed Coupling Reaction of an Enol Nonaflate with (Vinyl)tributylstannanes and Acetylenes: A Highly Stereoselective Synthesis of 8,18-13C2-Labeled Retinal

Here we report that enol nonaflates exhibit higher reactivity than the corresponding enol triflates in palladium-catalyzed cross-coupling reactions with various (vinyl)tributylstannanes and acetylenes. We also highlight the reaction of a vinyl nonaflate, containing two 1 3 C-labeled carbon atoms with an alkenyl stannane, which afforded the trisubstituted E-olefin stereoselectively in high yield. The E-olefin was then transformed into the corresponding all-E-retinal.