An Acid-Catalyzed O,N-Acyl Migration and Application to the Synthesis of N-(4-Isopropyl-2,2-dimethyl-3-oxo-3,4-dihydro-2H-benzo(1,4)oxazine-6-carbonyl) guanidine Methanesulfonate (KB-R9032), a Novel Na/H Exchange Inhibitor.
作者:Takeshi YAMAMOTO、Manabu HORI、Ikuo WATANABE、Hisayoshi TSUTSUI、Shoji IKEDA、Hiroshi OHTAKA
DOI:10.1248/cpb.47.22
日期:——
In the search for a practical synthesis of N-(4-isopropyl-2, 2-dimethyl-3-oxo-3, 4-dihydro-2H-benzo[1, 4]oxazine-6-carbonyl)guanidine methanesulfonate (KB-R9032), a potent Na/H exchange inhibitor, the acylation of methyl 4-hydroxy-3-isopropylaminobenzoate 6a with 2-bromoisobutyryl bromide was carried out in order to prepare an N-acyl derivative, 8a. However, an O-acyl derivative 7a was obtained selectively. Acylations of derivatives of 6a were examined. The results revealed that the O-acylation occurred because of the steric repulsion between the N-isopropyl moiety and the bulky acyl bromide. Then, we investigated the O, N-acyl migration of 7a. We found that the migration was catalyzed by carboxylic acid and that 8a was precipitated from a diisopropyl ether solution in good yield. Treatment of 8a with potassium carbonate and subsequent guanidine gave the synthetic intermediate for KB-R9032 in high yield.
寻找 N-(4-异丙基-2, 2-二甲基-3-氧代-3, 4-二氢-2H-苯并[1, 4]恶嗪-6-羰基)胍甲磺酸盐 (KB-) 的实用合成R9032),一种有效的Na/H交换抑制剂,用2-溴异丁酰溴对4-羟基-3-异丙氨基苯甲酸甲酯6a进行酰化,以制备N-酰基衍生物8a。然而,选择性地获得了O-酰基衍生物7a。检查了6a衍生物的酰化。结果表明,O-酰化的发生是由于N-异丙基部分和大的酰基溴之间的空间排斥而发生的。然后,我们研究了7a的O,N-酰基迁移。我们发现迁移是由羧酸催化的,并且 8a 从二异丙醚溶液中以良好的收率沉淀出来。用碳酸钾和随后的胍处理8a,以高产率得到KB-R9032的合成中间体。