摘要
方酸与醇反应生成方酸二酯 ,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 5 2 .5 %～ 87.4 %的手性仲醇 .新化合物的结构已用 IR,1 H NMR,MS和元素分析所证实 ,化合物 4 b的晶体结构用
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.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2001年第11期1846-1851,共6页
Chemical Journal of Chinese Universities
基金
国家自然科学基金 (批准号 :2 96 32 0 0 4)资助
