Preparation of Alkyl-Substituted Indoles in the Benzene Portion. Part 6. Synthetic Procedure for 4-, 5-, 6-, or 7-Alkoxy- and Hydroxyindole Derivatives.
作者:Masahiro FUJI、Hideaki MURATAKE、Mitsutaka NATSUME
DOI:10.1248/cpb.40.2344
日期:——
A novel method for the preparation of indole derivatives that are alkoxy- and hydroxy-substituted in the benzene portion of the indole nucleus is described. The acid-induced cyclization reaction of (arylsulfonyl)pyrrole derivatives (4a, 5b, and 5a) in the presence of an appropriate alcohol gave 4-, 5-, 6-, and 7-alkoxyindole derivatives (13 and 28), respectively, where the alkoxy group was originated from the alcohol employed. As an application of the present method, a short and efficient synthesis of two dopamine agonists (34 and 44) was attained by treating appropriately functionalized pyrrole derivatives (38 and 41) with an acid in the presence of 1, 3-propanediol, followed by deprotection of alkoxy function, and subsequent reduction with lithium aluminum hydride. A reaction mechanism is also suggested for the formation of an unusual product, 4-[2-(diprophlamino)-1-hydroyethyl]-6-hydroxyindole (46) in the reduction of N, N-dipropyl-(6-hydroxy-1-phenylsulfonyl)indole-4-acetamide (40).
本文介绍了一种制备吲哚核的苯部分被烷氧基和羟基取代的吲哚衍生物的新方法。(芳基磺酰基)吡咯衍生物(4a、5b 和 5a)在适当的醇存在下发生酸诱导环化反应,分别得到 4、5、6 和 7-烷氧基吲哚衍生物(13 和 28),其中的烷氧基来自所使用的醇。本方法的一个应用是,在 1,3-丙二醇存在下,用酸处理适当官能化的吡咯衍生物(38 和 41),然后脱去烷氧基,再用氢化铝锂还原,从而简短高效地合成了两种多巴胺激动剂(34 和 44)。在还原 N,N-二丙基-(6-羟基-1-苯磺酰基)吲哚-4-乙酰胺(40)的过程中,还提出了一种不常见产物 4-[2-(二rophlamino)-1-羟乙基]-6-羟基吲哚(46)的生成反应机理。