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