Reversible formation of aryloxenium ions from the corresponding quinols under acidic conditions
作者:Mrinal Chakraborty、Christopher F. Brzozowski、Michael Novak
DOI:10.1002/poc.2999
日期:2012.12
Because oxenium ion formation is reversible, the ion can only be detected by trapping with a nucleophile. Br– is an efficient trap under acidic conditions because, unlike N3–, it is not protonated under those conditions. Attempts to detect the oxenium ions 2a and 2b at pH 4.6 and 7.1 with N3– were unsuccessful indicating that oxenium ion formation only occurs under acidic conditions. The oxenium ion 2c
喹诺酚1是O-芳基氧鎓离子2和N-芳基氮鎓离子3的水合产物,目前正在研究用于医疗用途。在酸性条件下(pH值1-3)的Br动力学和产品-俘获表明1A,4-苯基-4-羟基-2,5-环己二烯酮,和1b,4- p甲苯基-4-羟基-2,5-环己二酮分别生成相应的氧离子2a和2b,作为稳态中间体。氧离子的形成和捕获与酸催化的二烯酮-苯酚重排竞争。由于氧离子的形成是可逆的,因此只能通过亲核试剂捕获才能检测到该离子。Br –在酸性条件下是一种有效的捕集阱,因为与N不同3 –,在这种情况下不会质子化。尝试检测在pH 4.6的oxenium离子2a和2b和7.1用N 3 -是不成功的指示oxenium离子形成只在酸性条件下发生。所述oxenium离子2c中无法从苯二酚1C酸性条件下,4-(苯并噻唑-2-基)-4-羟基-2,5-环己二,被Br下检测-捕集方法,即使该离子可以在被检测水解相应的酯,4c。尽管苯并噻