Transition Metal-catalyzed Intramolecular Cycloisomerization Of Furan/Yne Derivatives And Related Studies

Furans are important synthetic intermediates. They can participate in a variety of reactions such as Diels-Alder reaction, oxidation reaction and ring-opening reaction. This thesis is focused on the development of novel synthetic methodologies of heterocyclic compounds or polycyclic compounds based on the intramolecular or intermolecular reactions of furans using furan/ynes as starting materials. It includes the following four parts:1. Gold(Ⅰ)-catalyzed intramolecular cyclo-isomerization of furan/ynes bearing a silyloxy or allyloxy group has been developed, which provides a highly efficient access to protected1-naphthol derivatives with enal or enone moiety. The method offers several advantages such as high stereoselectivities, mild reaction conditions, and easily accessible starting materials. In addition, the naphthyl products could be further transformed into the important benzocoumarins in a one-pot procedure.2. Gold(Ⅰ)-catalyzed cycloisomerizations of1,4-furan/ynes afforded an efficient and stereoselective access to trisubstituted alkenes under mild reaction conditions. The reaction likely proceeds via cascade cyclization/Grob-type fragmentation with concomitant1,5-migration of furanyl group. In addition to furan rings, other heterocycles such as benzofurans, thiophenes and pyrroles underwent1,5-migrations equally well.3. A highly efficient palladium-catalyzed cascade reactions of propargyl carbonates bearing a furanyl group with organoborons has been developed. This methodology offers rapid access to polycyclic Diels-Alder cycloadducts in good to high yields. The thus formed oxygen-bridged products could be further converted to anthracene derivatives in a chemoselective manner under mild conditions.4. A highly efficient ZnCl2-catalyzed cascade reaction of enaminones with2-furylcarbinols under mild reaction conditions has been developed. This methodology offers a chemo-and diastereo-selective access to functionalized cyclopenta[b]pyrrole derivatives in good to excellent yields. The resulting azabicyclic compounds are important azacarboprostacyclin analogs, which are potentially useful in the treatment of thrombotic disease.