Asymmetric Organic Catalytic Claisen Rearrangement/Oxa-Michael Addition Tandem Reaction To Synthesize Chiral 3,4-Dihydropyrans

As oxygen-containing heterocyclic compounds,3,4-dihydropyran and its derivatives exist widely in natural products and are the core structures of many bioactive molecules and synthetic materials.Various and high-yield transformation reactions can take place depending on the unsaturation and oxidation levels of different groups around 3,4-dihydropyranes.Tandem reaction has been widely concerned by organic synthesis workers because its mild reaction conditions,high atomic utilization and in line with the concept of green chemistry.As an effective method for the formation of carbon-carbon bonds,Claisen rearrangement is one of the important synthetic methods for the construction of organic compounds.In this thesis,we realized the organic asymmetric catalytic tandem reaction of Claisen rearrangement and intramolecular Oxa-Michael addition of alyl vinyl ethers catalyzed by organic bifunctional catalyst.This reaction provided an approach that can economically synthesize chiral 3,4-dihydropyranes with high yield and excellent enantioselectivity and diastereoselectivity.This thesis related contents are:First of al,We briefly introduced the concept of Claisen rearrangement,its evolution and development.Then,we focus on the application of tandem reaction involved Claisen rearrangement,and put forward our research hypothesis.In addition,the applications and synthesis of 3,4-dihydropyran compounds were introduced.Then,we screened the conditions and expanded the substrate for the synthesis of chiral 3,4-dihydropyran compounds by Claisen rearrangement and intramolecular Oxa-Michael addition tandem reaction catalyzed by organic bifunctional catalyst.Moreover,we successfully realized the amplification of the tandem reaction and the derivatization of the product.At the same time,we also explored and studied the hydroalkoxylation/Claisen rearrangement/intramolecular Oxa-Michael addition multistep tandem reaction and the synthesis of chiral 3,4-dihydropyridine compounds.