作者:Gastón H. Rodríguez R、Jean-François Biellmann
DOI:10.1021/jo951063g
日期:1996.1.1
Highly enantioselective syntheses of enantiomers of homocitric acid lactones (R)-5a and (S)-5b are described. Thermal Diels-Alder cycloadditions of 2a and 2b to 1,3-butadiene produced adducts 3a and 3b, respectively. Oxidative ozonolysis of latter adducts gave products 4a and 4b which after acid treatment afforded a mixture with 5a and 5b as major component. Acid lactones 5a and 5b were converted into
描述了高柠檬酸内酯(R)-5a和(S)-5b的对映异构体的高度对映选择性的合成。2a和2b的热Diels-Alder环加成到1,3-丁二烯分别产生加合物3a和3b。后一种加合物的氧化臭氧分解得到产物4a和4b,其在酸处理后得到以5a和5b为主要成分的混合物。将酸性内酯5a和5b转化为其二甲基酯6a和6b,将其通过色谱法纯化。皂化后,将获得的产物结晶以产生(-)-和(+)-高纯酸内酯((R)-5a和(S)-5b)。Diels-Alder加合物3a和3b的非对映体过量(de)通过乙二醇8a,8b和外消旋8的Mosher酯测定。内酯2a和2b的Diels-Alder环加成产物与1,3-丁二烯的非对映选择性为96%。