The Preparation of Some Substituted Thiohydantoins and Thioimidazoles
作者:Mary Jackman、Mabel Klenk、B. Fishburn、B. F. Tullar、S. Archer
DOI:10.1021/ja01189a015
日期:1948.9
It has been shown that proper substitution a t the six position in 2-thiouracil resulted in increased antithyroid activity.' Astwood showed that 2thiohydantoin was half and 2-thioimidazole one and one half times as active as 2-thiouracil in goitrogenic potency.2 It seemed likely then that appropriately substituted thiohydantoins and thioimidazoles would show greater activity than the parent heterocycles
alkyl, aryl) positions and affords essentially single diastereomeric products with enantioselectivities higher than 95 % ee in most cases. Among the bifunctional Brønsted base/H‐bond catalysts examined, a known squaramide–tertiary amine catalyst and a newly prepared squaramide–tertiary amine catalyst provide the highest selectivity so far with either nitroolefins or vinyl ketones as the acceptor components
在有机催化迈克尔反应方法的基础上,开发了一种新的对映选择性合成5,5-二取代(季)乙内酰脲的方法,该方法涉及使用2-苄硫基-3,5-二氢咪唑-4-酮作为主要的乙内酰脲替代物。该方法是关于乙内酰脲的N 1(烷基,芳基,酰基),N 3(芳基)和C 5(直链/支链烷基,芳基)位置的取代方法的一般方法,并提供具有较高对映选择性的基本非对映体产物高于95% ee在多数情况下。在所研究的双功能布朗斯台德碱/氢键催化剂中,以硝基烯烃或乙烯基酮为受体组分,已知的方胺-叔胺催化剂和新制备的方胺-叔胺催化剂提供了迄今为止最高的选择性。动力学测量结果支持了一级反应速率对两个反应伙伴,供体模板和迈克尔受体的依赖性,而竞争性1 H NMR光谱实验表明模板具有很高的催化剂结合能力。