Development of a Scalable Process for the Insecticidal Candidate Tyclopyrazoflor. Part 1. Evaluation of [3 + 2] Cyclization Strategies to 3-(3-Chloro-1<i>H</i>-pyrazol-1-yl)pyridine
作者:Qiang Yang、Xiaoyong Li、Beth A. Lorsbach、Gary Roth、David E. Podhorez、Ronald Ross、Noormohamed Niyaz、Ann Buysse、Daniel Knueppel、Jeffrey Nissen
DOI:10.1021/acs.oprd.9b00127
日期:2019.10.18
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
描述了对[3 + 2]环化策略的评估,以制备用于杀虫候选菌typypyrazoflor(1)的关键中间体3-(3-氯-1 H-吡唑-1-基)吡啶。在经过验证的策略中,选择了涉及用丙烯酸甲酯对[3-肼基吡啶·2HCl]进行[3 + 2]环化的途径,以进行进一步优化。该途径提供了通过环化,氯化和氧化三个步骤容易地获得3-(3-氯-1 H-吡唑-1-基)吡啶的途径。通过3-((3,3,3-三氟丙基)硫代)丙酸的硝化,还原和酰胺形成反应进一步使3-(3-氯-1 H-吡唑-1-基)吡啶官能化,然后进行乙基化反应,得到1总共七个步骤。