# US 7,608,722 B2 · Preparation of 1,7,′-dimethyl-2′-propyl-2,5′-bi-1H-benzimidazole

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- Number: US 7,608,722 B2
- Document ID: US7608722B2
- Status: Granted
- Kind: B2
- Application number: 11/485,153
- Filed: 2006-07-12
- Published: 2007-02-15
- Granted: 2009-10-27
- Earliest claimed: 2005-07-22
- Assignees: Boehringer Ingelheim International GmbH
- Inventors: Helmut Heitger; Juan M. Rodriguez-Dehli; Rolf Dach
- Web page: https://patentgrep.com/patent/US7608722B2

## CPC

- C07D 235/18: with aryl radicals directly attached in position 2
- C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08)

## Abstract

A process for preparing 1,7′-dimethyl-2′-propyl-2,5′-bi-1H-benzimidazole of formula (I) reacting N-methyl-o-phenylenediamine of formula (II) or the salts thereof with 2-propyl-4-methyl-1H-benzimidazole-6-carboxylic acid of formula (III) or the salts thereof wherein the coupling and cyclization is achieved using 1,3,5-triazine and tertiary amine.

## Claims

### Claim 1

A process for preparing 1,7′-dimethyl-2′-propyl-2,5′-bi-1H-benzimidazole of formula (I)
reacting N-methyl-o-phenylenediamine of formula (II) or the salts thereof
with 2-propyl-4-methyl-1H-benzimidazole-6-carboxylic acid of formula (III) or the salts thereof
wherein the coupling and cyclization is achieved using 1,3,5-triazine and tertiary amine.

### Claim 2 (depends on 1)

The process according to claim 1, wherein the coupling and cyclization is achieved using a 2-chloro-4,6-disubstituted-1,3,5-triazine.

### Claim 3 (depends on 1)

The process according to claim 1, wherein the coupling and cyclization is achieved using 2,4,6-trichloro-1,3,5-triazine, 2-chloro-4,6-diphenoxy-1,3,5-triazine, 2-chloro-4,6-dibenzyloxy-1,3,5-triazine, 2-chloro-4,6-dimethoxy-1,3,5-triazine, 2,4-dichloro-6-phenoxy-1,3,5-triazine, 2,4-dichloro-6-benzyloxy-1,3,5-triazine, or 2,4-dichloro-6-methoxy-1,3,5-triazine.

### Claim 4 (depends on 1)

The process according to claim 1, wherein a polar solvent is used.

### Claim 5 (depends on 4)

The process according to claim 4, wherein the polar solvent is N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, methanol, ethanol, or 2-propanol.

### Claim 6 (depends on 1)

The process according to claim 1, wherein:
(a) the 2-propyl-4-methyl-1H-benzimidazole-6-carboxylic acid or the salt thereof is activated by a tertiary amine and a 1,3,5-triazine;
(b) the activated compound is coupled with N-methyl-o-phenylenediamine or the salt thereof to form an amide; and
(c) the amide obtained is cyclized by heating to form 1,7′-dimethyl-2′-propyl-2,5′-bi-1H-benzimidazole.

### Claim 7 (depends on 6)

The process according to claim 6, wherein:
step (a) is carried out at a temperature of −10° C. to 25° C.;
step (b) is carried out at a temperature of 0° C. to 50° C.; and
step (c) is carried out at a temperature of 20° C. to 80° C.

### Claim 8 (depends on 1)

The process according to claim 1, wherein a yield of more than 30% is achieved.