Oxibendazole

Oxibendazole is a benzimidazole drug that is used to protect against roundworms, strongyles, threadworms, pinworms and lungworm infestations in horses and some domestic pets. It is usually white to yellowish in appearance, and may take the form of a powder, tablet or paste.

Oxibendazole

Clinical data
AHFS/Drugs.com	International Drug Names
ATCvet code	QP52AC07 (WHO)
Legal status
Legal status	Veterinary use only
Identifiers
IUPAC name Methyl N-(6-propoxy-1H-benzimidazol-2-yl)carbamate
CAS Number	20559-55-1
PubChem CID	4622
ChemSpider	4461
UNII	022N12KJ0X
KEGG	D05293
CompTox Dashboard (EPA)	DTXSID5045625
ECHA InfoCard	100.039.873
Chemical and physical data
Formula	C12H15N3O3
Molar mass	249.270 g·mol^−1
3D model (JSmol)	Interactive image
SMILES CCCOC1=CC2=C(C=C1)N=C(N2)NC(=O)OC
InChI InChI=1S/C12H15N3O3/c1-3-6-18-8-4-5-9-10(7-8)14-11(13-9)15-12(16)17-2/h4-5,7H,3,6H2,1-2H3,(H2,13,14,15,16) Key:RAOCRURYZCVHMG-UHFFFAOYSA-N
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Synthesis

Oxibendazole synthesis:[1]

4‑Hydroxyacetamide (1) is alkylated with n-propyl bromide in the presence of potassium hydroxide to give the ether (2). Nitration of this product with nitric and sulfuric acids proceeds at the position ortho to the amide group (3), which is then reduced with SnCl₂ to yield the phenylenediamine derivative (4). Reaction of that intermediate with S-methyl isothiourea proceeds first by aromatic cyclisation to the guanidine derivative followed by elimination of methyl mercaptan to yield the 2-aminobenzimidazole system (5). Acylation with methyl chloroformate results in the formation of a urethane on the amino group to produce oxibendazole (6).

References

1. GB 1123317 corresp to P. P. Actor, J. F. Pagano, U.S. Patent 3,574,845 (1968, 1971 both to Smith, Kline & French).