Synthesis of optically pure compounds by enantiotopically differentiating monoacetalization of prochiral diketones
作者:Rudolf O. Duthaler、Peter Maienfisch
DOI:10.1002/hlca.19820650303
日期:1982.5.5
(2) and of its trans-isomer (3) with (2R,3 R)-2,3-butanediol (8) gives in both cases the monoacetals in high yield. While no enantiotopic differentiation is found for 3, a strong preference for the (9S,10 R)-monoacetal 9 is found for the cis-decalin-dione 2. The differentiation, reaching a maximal ratio of 9:1, is found to increase by conditions, which slow down the rate of reaction, e. g. lowering the
9-甲基-顺式十氢化萘-1,8-二酮(2)及其反式异构体(3)与(2 R,3 R)-2,3-丁二醇(8)的反应在两种情况下均产生单缩醛高产。虽然没有对映分化被发现为3,对于(9强烈偏好小号,10 - [R)-monoacetal 9是发现用于顺-decalin二酮2。发现达到最大比例9:1的差异会因以下条件而增加,这些条件会减慢反应速度,例如降低温度,酸催化剂的浓度或使用空间受限的催化剂。光学活性化合物的制备中使用本程序是由单缩醛9(从76%的收率得到的变换例示2)代入(9 - [R,10 - [R)-9-甲基-1-萘烷酮(12)。根据空间和电子效应讨论了二酮2和3的不同行为。