Esters of Pyromellitic Acid. Part II. Esters of Chiral Alcohols: Para Pyromellitate Diesters as a Novel Class of Resolving Agents and Use of Pyromellitates as Duplicands for Chiral Purification
作者:John B. Paine
DOI:10.1021/jo8005446
日期:2008.7.1
advantage of the easily separated benzyl diesters and their derived acid chlorides (19, 21), with the benzyl esters serving as temporary blocking groups removable by catalytic hydrogenolysis. Pyromellitate tetraesters (26) were prepared by base-catalyzed transesterification of the tetraethyl ester (25). Tri-l-menthyl pyromellitate (27b) was obtained by catalytic hydrogenolysis of benzyl tri-l-menthyl pyromellitate
提出了制备手性萜烯醇的均苯四酸酯的方法,包括d-(3)或l-薄荷醇(4),d-异薄荷醇(7),l-冰片(8)或d-(5)或l -异opinocampheol(6)。PMDA在CH的醇解2氯2 / ET 3 n个LED以单酯(例如,形成18)或二酯(11,12),视需要而定,取决于两个酸酐基团的差异反应性。容易分离的对位二酯(11)在HOAc的间位二酯(12)之前结晶。尼古丁(1,14)中的有效的解决为1:1克的盐与薄荷基(11A,11B)或冰片(11F)的对二酯,的什么承诺,是一大类新颖的拆分剂的原型。对-二-薄荷基均苯四酸酯(11a)的重结晶大大提高了所含d-薄荷醇的手性纯度(3),这是通过“复制”进行纯化的示例。特定的二酯的替代性合成接过容易分离苄酯和它们的衍生酰氯(的优点19,21),与作为临时保护基团苄基酯可移除地通过催化氢解。通过对四乙酯(25)进行碱催化的酯交换反应来制备均苯四