Catalytic palladium-mediated carbocyclizations: Cyclization and stereoselective trapping by a tethered nucleophile

The palladium-mediated carbocylizations of tetraene substrates with a tethered nucleophile is described in this dissertation (shown below is an example). This methodology provides a novel route for the construction of two rings via the net 1,4-addition of carbon and oxygen across an internal diene subunit.(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI) A growing number of novel fused or bridged bicyclic ring systems can be constructed in a stereoselective fashion from acyclic precursors using palladium-catalyzed polycyclization reactions. In the present chemistry, the 1,4-addition of carbon and hydrogen across the 1,3-diene occurs in a net anti fashion providing an unusual example of efficient 1,4-stereochemical control between two non-fused or -bridged rings. The cyclization proceeds with good levels of 1,2-stereoinduction when the substituent is positioned adjacent to the newly forming carbon-carbon bond. Substrates with methyl substitution in one of the two diene subunits cyclize in good yield and excellent diastereoselectivity. In one instance a quaternary stereocenter is generated in the product diastereoselectively and in good yield