Kinetics and Mechanism of <i>N</i>-Boc Cleavage: Evidence of a Second-Order Dependence upon Acid Concentration
作者:Ian W. Ashworth、Brian G. Cox、Brian Meyrick
DOI:10.1021/jo101767h
日期:2010.12.3
deprotection of the Boc-protected amine, thioester 2 to liberate AZD3409 1 have been studied in a mixture of toluene and propan-2-ol. The reaction rate was found to exhibit a second-order dependence upon the HCl concentration. This behavior was found to have a degree of generality as the deprotection of a second Boc-protected amine, tosylate 3 to yield amine 4 using HCl, sulfuric acid, and methane sulfonic
已在甲苯和丙-2-醇的混合物中研究了HCl催化的Boc保护的胺硫酯2释放AZD3409 1的动力学。发现反应速率表现出对HCl浓度的二级依赖性。发现这种行为具有一定程度的普遍性,因为使用HCl,硫酸和甲烷磺酸对第二个Boc保护的胺甲苯磺酸酯3脱保护以生成胺4表现出相同的动力学依赖性。相反,甲苯磺酸酯3的脱保护用三氟乙酸制得的三氟乙酸需要大量过量的酸才能获得合理的反应速率,并显示出对三氟乙酸盐浓度的逆动力学依赖性。从一般的酸催化分离机制来看,这些观察结果是合理的,该分离是由于质子化氨基甲酸叔丁酯的断裂而导致的可逆形成的离子-分子对的一般酸催化分离。