A method for preparing a phenylalanine derivative having a quinazoline-dione ring represented by the following formula (1) or a pharmaceutically acceptable salt thereof, comprising the following steps (a), (b) and (c):
(a) reacting an acyl phenylalanine derivative represented by the following formula (2):
with a carbonyl group-introducing reagent and a specific anthranilic acid derivative to thus form the corresponding carboxy-asymmetric urea derivative;
(b) converting the carboxy-asymmetric urea derivative into the corresponding quinazoline-dione derivative in the presence of a carboxyl group-activating agent:
(c) if desired, substituting an N-alkyl group for the hydrogen atom bonded to the nitrogen atom present in the quinazoline-dione ring of the quinazoline-dione derivative using an N-alkylation agent and then deprotecting the resulting product, when the substituent R3' which is a group corresponding to R3 is protected. According to this method, there can be obtained a phenylalanine derivative having a quinazoline-dione skeleton in a industrially favorably high yield.
一种制备具有下式(1)代表的
喹唑啉二酮环的苯丙
氨酸衍
生物或其药学上可接受的盐的方法,包括以下步骤(a)、(b)和(c):
(a) 使下式(2)所代表的酰基苯丙
氨酸衍
生物反应:
与羰基基团引入试剂和特定的
蒽酸衍
生物反应,生成相应的羧基不对称
脲衍
生物;
(b) 在羧基活化剂存在下,将羧基不对称
脲衍
生物转化为相应的
喹唑啉二酮衍
生物:
(c) 如果需要,使用 N-烷基化剂,用 N-烷基取代与
喹唑啉二酮衍
生物的
喹唑啉二酮环 中的氮原子键合的氢原子,然后当与 R3 对应的取代基 R3'被保护时,对所得产物进行脱 保护。根据这种方法,可以获得具有
喹唑啉二酮骨架的苯丙
氨酸衍
生物,其工业收率非常高。