The Synthesis Of Camphor-derived Schiff Bases And Amino Alcohols And Their Catalytic Performance In Asymmetric Reactions

The demand for chiral compounds in industrial production,medicine and biology is growing,and many excellent researchers are committed to the synthesis of chiral compounds.Among the methods of preparing chiral compounds,asymmetric catalytic synthesis has become one of the key methods due to its many advantages such as rapid process,high efficiency,and atomic economy.Asymmetric epoxidation and asymmetric Friedel-Crafts alkylation have been widely developed and applied as important methods for constructing carbon-oxygen bonds and carbon-carbon bonds,respectively.The design and synthesis of highly active and selective chiral catalysts is a highlight in the field of asymmetric catalysis.Schiff bases and amino alcohols derived from camphor ?-amino alcohol have good coordination ability,can be complexed with many metal salts to form catalysts,and have attracted much attention in asymmetric catalytic reactions.In this paper,the asymmetric epoxidations and asymmetric Friedel-Crafts alkylations were reviewed.A series of Schiff bases and amino alcohols derived from camphor ?-amino alcohol were synthesized and the catalytic properties of these ligands were investigated.My research work includes the following three parts:1.Preparation of Schiff bases and amino alcohols derived from chiral camphor ?-amino alcohol,preparation of Salen ligand,preparation of organocatalysts derived from quinine and quinidine.The readily available D-(+)-camphorsulfonic acid was chosen as the chiral source,after several steps of chemical reaction,camphor ?-amino alcohol 80 was synthesized,which was further derivatized into a series of chiral Schiff bases and amino alcohols.These ligands were compared with chiral Salen ligands,organocatalysts derived from quinine and quinidine for their catalytic reaction performance.The structures of the new ligands were confirmed by 1H-NMR,13C-NMR,and HRMS.2.Schiff bases 91 and amino alcohols 92,93,94 were used to catalyze asymmetric epoxidation of p-QMs.Under the optimized reaction conditions,Schiff base 91i and amino alcohol 93a showed good asymmetric induction ability,and the enantioselectivity was up to 94.0%,but the chemical yield was not satisfactory.These results provide a reference for further development of the asymmetric epoxidation of p-QMs.3.Schiff bases 91 and amino alcohols 92,93,94 were used to catalyze the asymmetric Friedel-Crafts alkylation of the pyrrole and the unsaturated cyclic ketoamide 106.By optimizing the reaction conditions,we obtained 84.6%chemical yield and 61.5%ee value.These results indicate that Schiff bases and amino alcohols with a camphor skeleton have great potential for catalyzing asymmetric Friedel-Crafts alkylation of the pyrrole and the unsaturated cyclic ketoamide.We expected that the ligands could be further modified to achieve excellent catalytic activity and enantioselectivity.