N-方酰麻黄碱配体的合成及催化前手性芳酮的不对称还原反应

方酸与醇反应成方酸二酯，后者与天然麻黄碱反应得到N-方酰麻黄碱或N-方酰双麻黄碱。单N-方酰麻黄碱与脂肪胺及硫氢化钠等反应合成了C-3位含氮和含硫的系列配体。首次将这些方酰麻黄碱配体经原位制备手性恶唑硼烷催化前手性芳酮及二酮的不对称还原反应，得到化学产率和e.e.值分别为85%-98%和52.5%-87.4%的手性仲醇。新化合物的结构已IR，^1H NMR,MS和元素分析所证实，化合物4b的晶体结构用X射线射确认。

Studies on the Synthesis of Squaric Acid Ephedrine and Their Application in Asymmetric Catalytic Borane Reduction of Prochiral Ketones

Seven squaric acid ester amides or squaric acid diamides have been conveniently prepared by the reaction of natural ephedrine and squaric acid diesters, in which the later can be sythesized by refluxing squaric acid in the corresponding alcohols. When squaric acid amide ester 4a reacted with alkyl amines or was treated with aqueous sodium hydrosulfide, the new ligands which contain nitrogen or sulfur atom at {C 3} of squaric acid were obtained. Five ligands were synthesized for the first time. The chiral oxazaborolidines formed in situ have been used in the enantioselective borane reduction of prochiral ketones and diketones to afford the alcohols in the range 85%-98% yields and 52.5%-87.4% enantiomeric excess respectively. All new ligand structures were comfirmed by IR, 1H NMR, MS and elemental analysis, the crystal structure of compound 4b was lerrified by X ray diffraction.