A process for the preparation of N-alkyl-3,4-dialkyloxyanilines and derivatives thereof
申请人:CHEMAGIS LTD.
公开号:EP0549263A2
公开(公告)日:1993-06-30
The invention provides a process for the preparation of N-alkyl-3,4-dialkyloxyanilines and derivatives thereof of the formula I
wherein R1 and R2 are each identical or different lower alkyl groups or R1 and R2 taken together form a methylene bridge and R3 is H or lower alkyl comprising bromination of a compound of formula II
wherein R1 and R2 are as defined above to form a compound of formula III
and then reacting said compound with an aqueous alkyl amine or ammonia of the formula R3NH2 wherein R3 is as defined above to effect amination of the bromo amination of the bromo intermediate of formula III to form the compounds of formula I.
The present invention relates to a process for the preparation of N-alkyl-3,4-dialkyloxyanilines and derivatives thereof.
More particularly the present invention relates to a process for the preparation of N-alkyl-3,4-dialkyloxyanilines, which compounds can be used as intermediates in the preparation of quinazolinone and quinazolin- thione derivatives having antibacterial properties.
Thus the compounds produced by the process of the present invention can be used, e.g., to produce the known antibacterial compound oxolinic acid, which is 5-ethyl-5,8-dihydro-8-oxo-1,3-dioxolo[4,5-g] quinoline-7- carboxylic acid, and its salts.
In U.S. Patent 3,748,331 there is described inter alia, a process forthe preparation of compound of formula A
wherein R3 signifies an alkyl radical of 1 to 5 carbon atoms and R1=R2=methylene bridge from compounds of formula I
In said patent, compounds of formula I are prepared by a three-step synthesis (Scheme 1) involving:
a. nitration of 1,2-methylenedioxybenzene (MDB) (3a) to produce the nitro compound (4a) ;
b. subsequent reduction of 4a with hydrogen and a suitable catalyst (e.g. palladium on carbon) to produce 3,4-methylenedioxyaniline (MDA) (2b); and
c. alkylation of 2b to Produce N-alkyl MDA (I, R3=alkyl).
The following scheme illustrates the known synthesis of N-alkyl MDA.
本发明提供了一种制备 N-烷基-3,4-二烷氧基苯胺及其式 I 衍生物的工艺
其中 R1 和 R2 分别为相同或不同的低级烷基,或 R1 和 R2 共同形成亚甲基桥,R3 为 H 或低级烷基,包括式 II 化合物的溴化反应
其中 R1 和 R2 如上定义,形成式 III 的化合物
然后使所述化合物与水基烷基胺或式 R3NH2 的氨反应,其中 R3 如上文所定义,以实现式 III 的溴中间体的胺化,从而形成式 I 的化合物。
本发明涉及一种制备 N-烷基-3,4-二烷氧基苯胺及其衍生物的工艺。
更具体地说,本发明涉及一种制备 N-烷基-3,4-二烷氧基苯胺的工艺,该化合物可用作制备具有抗菌性能的喹唑啉酮和喹唑啉硫酮衍生物的中间体。
因此,本发明工艺生产的化合物可用于生产已知的抗菌化合物噁唑啉酸,即 5-乙基-5,8-二氢-8-氧代-1,3-二恶茂并[4,5-g]喹啉-7-羧酸及其盐类。
在美国专利 3,748,331 中,特别描述了制备式 A 化合物的工艺。
其中 R3 表示 1 至 5 个碳原子的烷基,R1=R2=亚甲基桥来自式 I 的化合物
在上述专利中,式 I 化合物是通过三步合成法制备的(方案 1),包括: 1:
a. 硝化 1,2-亚甲基二氧苯 (MDB) (3a),生成硝基化合物 (4a) ;
b. 随后用氢气和合适的催化剂(如碳上钯)还原 4a,生成 3,4-亚甲二氧基苯胺(MDA)(2b);以及
c. 对 2b 进行烷基化反应,生成 N-烷基 MDA(I,R3=烷基)。
下图说明了 N-烷基 MDA 的已知合成方法。