Development of potential manufacturing routes for substituted thiophenes – Preparation of halogenated 2-thiophenecarboxylic acid derivatives as building blocks for a new family of 2,6-dihaloaryl 1,2,4-triazole insecticides

• John W. Hull Jr.,
• Duane R. Romer,
• David E. Podhorez,
• Mezzie L. Ash and
• Christine H. Brady

Beilstein J. Org. Chem. 2007, 3, No. 23, doi:10.1186/1860-5397-3-23

• development have been the 2,6-dihalo 1,2,4-triazoles XR-693 and XR-906, which require a supply of the halogenated 2-thiophenecarboxylic acid derivatives 1, 2, and 3 for assembly of the C-ring portion of the triazole products. Results Potential manufacturing routes to three halogenated 2-thiophenecarboxylic

• pests in mind, this family of compounds has been under investigation for aphid, mite, and whitefly control in food crop protection as well as ornamental applications. Two specific target molecules for development have been the 2,6-dihalo 1,2,4-triazoles XR-693 and XR-906, each containing a halogenated

2-Arylhydrazononitriles as building blocks in heterocyclic synthesis: A novel route to 2-substituted- 1,2,3-triazoles and 1,2,3-triazolo[4,5-b]pyridines

• Saleh M. Al-Mousawi and
• Moustafa Sh. Moustafa

Beilstein J. Org. Chem. 2007, 3, No. 12, doi:10.1186/1860-5397-3-12

• . Instead the hydrolyzed product 5 was formed. Introduction Interest in 1,2,3-triazole chemistry has recently been revived. [1][2][3][4] Zaprinast (1) is used as cyclic AMP phosphodiasterase inhibitor. [5] Plenty of 1,2,3-triazoles have also been reported to have useful pharmaceutical potential. [6][7][8

• refluxing 2a with hydroxylamine hydrochloride in DMF/piperidine afforded 1,2,3-triazoles whose structure was established by X-ray crystal structure. [11] On the other hand reacting 2b with hydroxylamine hydrochloride in DMF/piperidine afforded 5-amino-1,2,4-triazole via a rare Tiemann-like rearrangement. In

• that can be assigned as 1,2,4-oxadiazolylphenylhydrazone structure 4 or the isomeric acetylamino-1,2,3-triazole structure 6. Phenylhydrazono-1,2,4-oxadiazoles have been reported to rearrange thermally into acylamino-1,2,3-triazoles. [12] Compound 5 could be obtained via refluxing 3 in DMF in the