Evaluation of the [3 + 2] cyclization strategies to prepare a key intermediate, 3-(3-chloro-1H-pyrazol-1-yl)pyridine, for the insecticidal active Tyclopyrazoflor is described. Among the validated strategies, the route involving [3 + 2] cyclization of 3-hydrazinopyridine 2HCl with methyl acrylate was selected for further optimization. This route provided ready access to 3-(3-chloro-1H-pyrazol-1-yl)pyridine in three steps via cyclization, chlorination, and oxidation. Further functionalization of 3-(3-chloro-1H-pyrazol-1-yl)pyridine via nitration, reduction, and amide formation with the 3-((3,3,3-trifluoropropyl)thio)propanoic acid, followed by ethylation rendered Tyclopyrazoflor in a total of 7 steps.

Evaluation of [3 + 2] cyclization strategies to 3-(3-Chloro-1 H-pyrazol-1-yl)pyridine, a key intermediate for the insecticidal active tyclopyrazoflor

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.