New Insights into the Acid-Promoted Reaction of Caffeic Acid and Its Esters with Nitrite: Decarboxylation Drives Chain Nitrosation Pathways toward Novel Oxime Derivatives and Oxidation/Fragmentation Products Thereof
作者:Alessandra Napolitano、Marco d'Ischia
DOI:10.1021/jo015965v
日期:2002.2.1
methyl ester (1b) reacted with NO(2)(-) chiefly via ring nitration and/or dimerization to give 5a, the novel nitrated neolignan derivative 10, and the parent 6. Chlorogenic acid (1c) afforded only the ring nitrated derivative 5b. A unifying mechanism for the reaction of 1a and its esters with NO(2)(-) is proposed involving reversible formation of nitroso intermediates via chain nitrosation at the 2-position
在含有1%甲醇的0.05 M醋酸盐缓冲液(pH 4)中,咖啡酸(1a)(2 x 10(-3)M)与亚硝酸盐(NO(2)(-))(4 x 10(-3)平稳反应M)作为主要产品提供较小的新型2-羟基-和2-甲氧基醛肟7a,b,2-环氧醛肟9a,3,4-二羟基苯甲酸,3,4-二羟基苯甲醛和已知的呋喃喃3c和苯并恶嗪酮4b金额。在较低的1a浓度下(例如1 x 10(-4)M),主要产物为7a,而0.1 m 1a和0.5 M NO(2)(-)3c和9a为主要产物。在pH 2时,7a与3,4-二羟基苯甲醛和一些9a仍然是最丰富的产物,而在pH 1时,9a和3,4-二羟基苯甲醛的产率更高。没有获得关于环硝化产物的证据,包括先前报道的4,5-二羟基-2-硝基苯甲醛。在2 x 10(-3)M浓度和pH 4下 咖啡酸甲酯(1b)主要通过环硝化和/或二聚反应与NO(2)(-)反应生成5a,新型硝化的新木脂素衍生