Study On The Synthesis Of O - Aliphatic Alcohols By Amination - Dipolar Reversal - Nucleophilic Addition Strategy

α-Amino alcohols are a class of very important compounds, which are widely present in natural products and biologically active molecules. Development of new and efficient methods for the synthesis of α-amino alcohols has been attracted much attention and has become an active topic in synthetic community.α-Amino anions are a type of highly useful intermediates, which can react with various electrophiles to access various amines. However, it is not easy to obtain α-amino anions under mild conditions. Usually it requires a strong base and anhydrous conditions, thus greatly limiting the application of the method. Very recently we developed an efficient method which can transform carbonyl compounds into α-imino anions. The α-imino anions may react with ketones and aldehydes smoothly, providing an attravtive and direct method to synthize various α-amino alcohols.The research in this thesis mainly includes the following two parts:(1) A varety of cyclic amino alcohols have been obtained from dicarbonyl compounds in high yields(57-92%) with good diasereoselectivities(dr: 1:1-20.8:1) under very mild conditions by using 2,2-diphenylglycine as the aminative-Umpolung reagent. The reaction starts with the Shiff base formation between 2,2-diphenylglycine and dicarbonyl compounds, followed by decarboxylation to form imino anions and intramolecular nucleophilic addition to give the desired amino alcohols.(2) A class of axially chiral biaryl pyridoxals have been developed via multiple synthesis. The chiral pyridoxals have been successfully applied to catalyze the asymmetric synthesis of chiral cyclic amino alcohols from dicarbonyl compounds. The desired cyclic amino alcohols were obtained in 22-45% yields with 57-70% ee’s under very mild conditions. A plausible mechanistic pathway has been proposed for the reaction.