Clemizole

Clemizole

File:Clemizole.png
Systematic (IUPAC) name
1-[(4-chlorophenyl)methyl]-2-(pyrrolidin-1-ylmethyl)benzimidazole
Identifiers
CAS Number	442-52-4
ATC code	none
PubChem	CID: 2782
ChemSpider	2680
UNII	T97CB3796L Y
ChEBI	CHEBI:52140
ChEMBL	CHEMBL1407943
NIAID ChemDB	033090
Chemical data
Formula	C19H20ClN3
Molecular mass	325.84 g/mol
SMILES Clc1ccc(cc1)Cn3c(nc2ccccc23)CN4CCCC4
InChI InChI=1S/C19H20ClN3/c20-16-9-7-15(8-10-16)13-23-18-6-2-1-5-17(18)21-19(23)14-22-11-3-4-12-22/h1-2,5-10H,3-4,11-14H2 Key:CJXAEXPPLWQRFR-UHFFFAOYSA-N

Clemizole is an antihistamine.

Synthesis

Benzimidazoles substituted with an alkylamine at position 2 have a venerable history as H1 antihistaminic agents. The standard starting material for many benzimidazoles consists of phenylenediamine, or its derivatives.

File:Clemizole synthesis.svg

Clemizole synthesis:

Reaction of that compound with chloroacetic acid can be rationalized by invoking initial formation of the chloromethyl amide. Imide formation with the remaining free amino group closes the ring to afford th 2-chloromethyl benzimidazole (3). Displacement of halogen with pyrrolidine affords the alkylation product. The proton on the fused imidazole nitrogen is then removed by reaction with sodium hydride. Treatment of the resulting anion with α,4-dichlorotoluene gives the H₁ antihistaminic agent clemizole (5).

See also

• Chlormidazole