A Novel Octahydropyridobenzothiazepine Metabolite in Human Urine: Biomimetic Formation from the Melanogen 5-<i>S</i>-Cysteinyldopa and Formaldehyde via a Peculiar Sulfur-Controlled Double Pictet−Spengler Condensation
作者:Paola Manini、Marco d'Ischi、Giuseppe Prota
DOI:10.1021/jo991969c
日期:2000.7.1
4-thiazepine moiety. Under physiologically relevant conditions, i.e., in 0.1 M phosphate buffer pH 7.4 and at 37 degrees C, the 7,8-tetrahydroisoquinoline 5 was the sole detectable intermediate in the formation of 2. N-Acetylcysteinyldopa (4) reacted likewise with formaldehyde to give the 7, 8-dihydroxytetrahydroisoquinoline 6. The anomalous regiochemistry underlying formation of 5 and 6 was rationalized
高效液相色谱法的证据表明,在某些人类尿液样品中出现了一种新的儿茶酚代谢产物(3R,7S)-3,7-dicarboxy-10,11-dihydroxy-2,3,4,5,6,7,8, 9-八氢吡啶并[4,3-g] [1,4]苯并硫氮杂pine(2)。该化合物显示为尿黑色素原5-S-半胱氨酰多巴(1)与甲醛的双Pictet-Spengler缩合生成,其中六元环邻位与活化羟基的区域选择性形成有助于随后的封闭七元1,4-硫氮杂moiety部分中的一部分。在生理相关条件下,即在pH 7.4的0.1 M磷酸盐缓冲液中和在37摄氏度下,7,8-四氢异喹啉5是形成2的唯一可检测中间体。N-乙酰半胱氨酸多巴(4)同样与甲醛反应生成7、8-二羟基四氢异喹啉6。借助在模型烷硫基邻苯二酚10上进行的AM1 / PM3计算,合理化了形成5和6的异常区域化学反应,从而预测了在邻位而不是对位活化羟基上更高的HOMO控制反