Switching diastereoselectivity of direct Mannich-type reaction of cyclic ketones by polymeric laponite nanoclay catalyst
作者:Bagher Eftekhari-Sis、Sahar Mohajer、Maryam Zirak、Gholam Reza Mahdavinia、Orhan Büyükgüngör
DOI:10.1007/s13738-015-0772-z
日期:2016.4
afforded corresponding Mannich adducts. In the case of cyclohexanone, stereoselectivity was changed depending on the nature of the substitution on benzaldehydes, in which, moderate electron-donating and electron-withdrawing groups afforded the anti isomer as major products, but strongly electron-donating substituted benzaldehydes led to syn isomer as the major Mannich adducts. Mannich reaction with cycloheptanone
开发了一种基于HPMC(羟丙基甲基纤维素)的新型聚合锂皂石纳米粘土多相催化体系,用于酮与取代的苯甲醛和苯胺的直接曼尼希式反应,从而以高至高收率提供相应的β-氨基酮。有趣的是,环状酮表现出不同的化学选择性。环戊烷酮进行羟醛缩合反应生成交联的羟醛产物,而环己酮和环戊酮则得到相应的曼尼希加合物。在环己酮的情况下,立体选择性随苯甲醛上取代基的性质而变化,其中适度的供电子和吸电子基团提供了抗异构体为主要产物,但强供电子的取代苯甲醛导致合成异构体为主要的曼尼希加合物。曼尼希与环庚酮的反应导致曼尼希加合物具有出色的顺式选择性。