Gold-catalyzed Intermolecular Cycloaddition Of Conjugated Enynones With Nirtones

Highly substituted furans can be found as core structure in many natural products,commercially important pharmaceutical,food taste enhancers,bioregulators and dynes.In synthetic chemistry,it is also considered as a kind of synthetic intermediate for the construction of numerous cyclic and acyclic compounds.Many chemists focused their research interests on the development of new methodologies for the synthesis and transformation of this kind of compounds.Gold complexes known as a kind of powerful Lewis acid,has extensively studied in catalytic reactions in past decade.For example,they can readily activate alkynes, allenes and olefins to react with a variety of nucleophiles.In this thesis,we have focused on the synthesis of highly substituted furan by the cycloaddition reaction of conjugated enynones with nitrones.This thesis includes the following three parts:Partâ… :High diastereoselective cycloaddition reaction of conjugated enynones with nitrones.Under the catalysis of Ph₃PAuOTf,we found that the reaction of 2-(phenylethynyl)cyclohex-2-enone with(Z)-N-benzylideneaniline oxide(nitrone) can give a novel heterobicyclic product with high regioselectivity and diastereoselectivity.Partâ…¡:Transformation of productsThe products were treated with SmI₂ or cerium(â…£) ammonium nitrate(CAN) could give oxazine and highly substituted furan compounds,respectively,in good yields by a chemoselective ring opening.Partâ…¢:Synthesis and application of chiral biphenyl type phosphorus ligandsThree chiral ligands,Such as(R)-MeO-BIPHEP,(R)-C1TunaPhos and (R)-C3TunaPhos have been synthesized from m-bromoanisole according to reference's procedure.We are pleased to find that(R)-C1TunaPhos can give the best ee value.