Clemizole

Clemizole
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 YesY
ChEBI CHEBI:52140
ChEMBL CHEMBL1407943
NIAID ChemDB 033090
Chemical data
Formula C19H20ClN3
Molar mass 325.84 g/mol

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.

Clemizole synthesis:[1][2]

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

References

  1. ↑ Jerchel, D.; Fischer, H.; Kracht, M. (1952). "Zur Darstellung der Benzimidazole". Justus Liebigs Annalen der Chemie 575 (2): 162. doi:10.1002/jlac.19525750204.
  2. ↑ GB 703272; M. Schenck, W. Heinz, U.S. Patent 2,689,853 (both 1954 to Schering AG).



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