Chain-walking strategy for organic synthesis: catalytic cycloisomerization of 1,n-dienes.

The catalytic construction of carbon-carbon bonds in small organic molecules via chain walking is described. Catalytic cycloisomerization of 1,n-dienes via chain walking was achieved using a palladium-1,10-phenanthroline catalyst to form five-membered-ring products. By means of a cycloisomerization/hydrogenation protocol, 1,7- to 1,14-dienes were selectively converted to bicyclo[4.3.0]nonane derivatives. The use of chain walking provides a new method in organic synthesis to functionalize unreactive carbon-hydrogen bonds by letting the catalyst look for preferable bond-forming sites by moving around on the substrate.