Molybdenum Or Tungsten-Catalyzed Alkene Functionalization Reactions

In the synthesis of natural products and pharmaceuticals,the functionalization of olefins provides a convenient and effective entry to construct these complex molecules.Significant advances have been achieved in the functionalization of olefins by application of oxidative,reductive,or redoxneutral strategy.However,the asymmetric functionalization of olefins still poses great challenges.The dissertation can be divided into the following three aspects regarding the investigation of asymmetric functionalization of olefins.Section one:Molybdenum-catalyzed asymmetric anti-dihydroxylation of allylic alcohols.Asymmetric dihydroxylation of olefins is one of the basic reactions in organic synthesis,but the development of asymmetric trans-dihydroxylation lags behind its syn-variant.Herein,we have achieved a highly enantio-and diastereoselective anti-dihydroxylation of allylic alcohols by using a chiral molybdenum-bishydroxamic acid complex as catalyst and environmentally friendly hydrogen peroxide as oxidant.Using this protocol,we can obtain diverse 1,2,3-triols in highly enantio-and diastereoselective manner.Section two:Photocatalytic hydroacylation of trifluoromethyl alkenes.After being attacked by nucleophiles,trifluoromethyl olefins can easily undergoβ-F elimination reaction.By using TBADT as a photocatalyst for hydrogen atom transfer(HAT)activation of acyl C-H,we effectively avoided β-F elimination during the hydroacylation of trifluoromethyl olefins,offering a facile and efficient entry to β-CF3 ketones with 100%atom economy and a good tolerance of a series of functional groups.Section three:Nickel/photo-cocatalyzed asymmetric acyl-carbamoylation of alkenes.Transition metal-catalyzed dicarbonation of olefins is a powerful tool to install two different carbon components.By applying redox-neutral or reductive strategy,significant progress has been achieved in two or three-component dicarbonation reaction of olefins.Herein,we applied the photo-redox strategy to realize the asymmetric dicarbonation of olefins.Under the cooperative catalysis of chiral nickel-PHOX complex and TBADT photocatalyst,the asymmetric acyl-carbamoylation of carbamoyl chloride-tethered olefins with aldehydeswas achieved.This is the first example of asymmetric dicarbonation reaction of olefins under the cocatalysis of hydrogen transfer photocatalyst and transition metal.Using this protocol,we synthesized a series of chiral oxindoles with a challenging quaternary stereocenter.