The Behavior of 1,4-Benzodiazepine Drugs in Acidic Media, Part XVII. Kinetics and Mechanism of the Acid-Base Equilibrium and the Hydrolysis of Benzodiazepinooxazines.
作者:Yukihisa KURONO、hidetoshi TANI、Tomonari KUWAYAMA、Keiichiro Hatano、Tamotsu YASHIRO、Ken IKEDA
DOI:10.1248/cpb.39.3323
日期:——
Ring-opening and ring-closing (acid-base equilibrium) reactions of the six-membered oxazine of benzodiazepinoxazines (BZINs) and the subsequent hydrolyses of the diazepine ring have been investigated kinetically and compared with the reactions of benzodiazepinooxazoles (BZOLs) which have the five-membered oxazolidine ring. The ring-closing reaction for BZINs is slower than that for BZOLs due to the increase in the degree of freedom for the moving molety of BZINs. The rates of the ring-opening reactions are almost independent of the substituents at 12b-position (H-(1), CH3-(2), and C6H5-(3)), indicating that an attacking proton may approach equally (non-sterically) to the lone pair of N5 atoms. Possible conformational aspects of BZINs in solution are proposed. Cleavages (hydrolyses) of the diazepine ring occur at the C12b-N5 (iminium) bond for 2 and 3 and are 10-100 times faster than those for the corresponding BZOLs. For 1, in contrast to 2 and 3, hydrolysis of the amide bond (N8-C7) of the diazepine ring takes place instead of the iminium bond, similar to the case of 11b-hydrogen BZOL.
我们对苯并二氮杂卓(BZINs)的六元恶嗪的开环和闭环(酸碱平衡)反应以及随后的二氮杂卓环水解进行了动力学研究,并与具有五元恶唑烷环的苯并二氮杂卓(BZOLs)的反应进行了比较。由于 BZINs 移动分子的自由度增加,BZINs 的开环反应比 BZOLs 慢。开环反应的速率几乎与 12b 位上的取代基(H-(1)、CH3-(2) 和 C6H5-(3))无关,这表明攻击质子可以平等地(非立体地)接近 N5 原子的孤对子。提出了 BZIN 在溶液中的可能构象。对于 2 和 3,二氮杂环的裂解(水解)发生在 C12b-N5(亚氨基)键上,速度比相应的 BZOL 快 10-100 倍。与 2 和 3 相反,1 的水解发生在二氮杂环的酰胺键(N8-C7)上,而不是亚氨基键上,这与 11b 氢 BZOL 的情况类似。