Chiral amide and related parties ligand synthesis and asymmetric catalysis
|Keywords||Asymmetric Catalysis Fang acylated amino alcohols Acylated amino acid side Thiazolidine chiral acid Chiral sulfonamide Reduction of prochiral ketones Asymmetric aldol reaction|
Asymmetric Organic Synthesis and Catalysis is a hot issue today . This is the first synthesis of natural ephedrine and L- proline as chiral C3 position of the square ring were square esters, amides and thio side Squarylium ( ester ) , single , square hands of acylated amino alcohols with body ; square ring C3 position were square ester and amide side square acylated amino acids and chiral bridging the two sides acylated amino acid ligands. These chiral amide ligands are square new compounds , three of which party acylated amino alcohols and a square aminoacylase ligands by single-crystal X-ray diffraction analysis confirmed its absolute configuration . Acylated Prolinol in square prochiral ketones catalyzed asymmetric reduction reaction, its enantioselectivity far superior to other similar ligands , ee values ??of up to 99%. Ligand used in a variety of such aryl ketone reduction , ee values ??generally above 90% , showing excellent universal , high efficiency is expected to be a class of selective catalysts . Acylated amino acid side also shows the amino acid than the corresponding sulfonyl much higher enantioselectivity (ee values ??up to 96% ) . The two sides acylated amino acids in the reduction reaction of diketone obtain the highest value of 90% ee . Chinese ligand heteroatoms the C3 position in the reaction may play the role of a Lewis base , so that such ligands have a dual functionality. C2 position on a variety of aryl-substituted thiazolidine acid ligand catalytic asymmetric reduction of prochiral ketones reactions were studied, we find such ligands show with the famous CBS catalyst results opposite enantioselectivity proposed possible reaction mechanism . The effects of N- sulfonyl amino acid -catalyzed asymmetric aldol reaction , the results show sulfonyl D- phenylglycine catalytic reaction product obtained only configuration and other sulfonyl amino contrary , ee values ??are higher ( up to 81.7% ) . In this regard we also propose a hypothetical transition state model . Also synthesized a new class of N- sulfonylated diamine pyrrolidine compounds which are expected to be catalyzed asymmetric carbon-carbon bond formation reaction effective catalysts.