A Robust, Eco‐Friendly Access to Secondary Thioamides through the Addition of Organolithium Reagents to Isothiocyanates in Cyclopentyl Methyl Ether (CPME)
The nucleophilic addition of widely available and variously functionalized organolithiumreagents to isothiocyanates represents a straightforward, high‐yielding, one‐pot method to access secondary thioamides. The simple reaction conditions required and the broad scope (>50 cases examples) makes it a robust and reliable method to access both simple and complex thioamides, including enantiopure ones
Brønsted Acids as Additives for the Direct Asymmetric Aldol Reaction Catalyzed by <scp>l</scp>-Prolinethioamides. Direct Evidence for Enamine−Iminium Catalysis
catalyst loading can be lowered to 2.5 mol %. More than 20 different acids were investigated as an additive, and its role as cocatalyst has been discussed. Furthermore, reactions of l-prolinethioamide salts with acetone have been monitored using ESI-MS and 1H NMR techniques, giving insight into the mechanism of the directaldolreaction. The presumed formation of the iminium salt 10 has been unambiguously
使用质子化的1-脯氨酸硫酰胺代替游离碱衍生物1作为直接添加醇醛的有机催化剂对反应的收率和立体化学过程均具有深远且可观的影响。4-硝基苯甲醛(2)在质子化催化剂1 -TFA的存在下与丙酮反应,得到的醛醇产物3的收率最高为99%,ee最高为98%。催化剂负载量可降低至2.5mol%。研究了20多种不同的酸作为添加剂,并讨论了其作为助催化剂的作用。此外,反应升用丙酮-prolinethioamide盐已经使用ESI-MS和被监测11 H NMR技术,可深入了解直接羟醛反应的机理。明确确定了亚胺盐10的推测形成。