A modified process to obtain Carvedilol
Publication Date: 2005-Oct-26
The IP.com Prior Art Database
Carvedilol is obtained by reaction of 4-(oxiran-2-yl-methoxy)-9H-carbazole with 2-(2-methoxyphenoxy)ethylamine hydrochloride in a presence of potassium carbonate in toluene solvent.
A MODIFIED PROCESS TO OBTAIN CARVEDILOL
Carvedilol, chemically known as (±) 1-(9H-carbazol-4-yloxy)-3-[[2-(2-methoxyphenoxy)-ethyl]-amino]-2-propanol, having structural formula I is a nonselective β-adrenergic blocking agent with α1 blocking activity.
The process of preparing carvedilol is disclosed in US 4503067 by the following reaction:
in which 4-(oxiran-2-ylmethoxy)-9H-carbazole (II) reacts with 2-(2-methoxyphenoxy)ethylamine (III) in a molar ratio of 1:1,1 to form carvedilol. By this method a considerable amount of by-product bis-derivate (IV) is formed and crude carvedilol requires two or three crystallizations to meet EP specifications. Therefore a low yield of the desired product is obtained.
Moreover, the process to obtain 2-(2-methoxyphenoxy)ethylamine free base involves an additional cost in the manufacture of carvedilol. Due the instability of the 2-(2-methoxyphenoxy)ethylamine, the commercially available raw material is its hydrochloride salt.
Accordingly, the process described herein presents the advantage that uses 2-(2-methoxyphenoxy) ethylamine hydrochloride as a starting material. It has been demonstrated that the hydrochloride salt reacts as well as the free base with 4-(oxiran-2-ylmethoxy)-9H-carbazole.
Furthermore, the present invention provides a method to obtain crude carvedilol with a content of IV lower than 1,0%. According to our know-how this level is the maximum value to assure crystallized carvedilol that meet EP specifications with only one crystallization.
The process for preparing carvedilol comprises:
- The reaction of 4-(oxiran-2-ylmethoxy)-9H-carbazole (II) with 2-(2-methoxyphenoxy)ethylamine hydrochloride (III) in a molar ratio of 1:1,4 in a presence of potassium carbonate in a molar ratio of 0,53 to 1,07, more preferably...