Toward the Development of a Manufacturing Process for the Insecticide Tyclopyrazoflor. Part I. Evaluation of Strategies using Ullmann Coupling of Pyrazole Derivatives
作者:Xiaoyong Li、Qiang Yang、Beth A. Lorsbach、Ann Buysse、Noormohamed Niyaz、Li Cui、Ronald Ross
DOI:10.1021/acs.oprd.2c00296
日期:2022.12.16
Synthetic strategies based on Ullmann coupling of functionalized pyrazoles and 3-halopyridine to access the insecticide tyclopyrazoflor (1) were evaluated. A five-step route featuring a middle-stage Ullmann coupling approach was selected as the lead route for optimization and was scaled up in a pilot plant at more than 50 kg scale of each step. This route started from reductive chlorination of 4-nitropyrazole
评估了基于官能化吡唑和 3-卤代吡啶的 Ullmann 偶联以获得杀虫剂 tyclopyrazoflor ( 1 ) 的合成策略。选择具有中间阶段 Ullmann 耦合方法的五步路线作为优化的主要路线,并在试验工厂中以每步 50 公斤以上的规模扩大。该路线从 4-硝基吡唑的还原氯化开始,然后乙酰化以提供N -(3-chloro-1 H -pyrazol-4-yl)acetamide 作为关键的偶联亲核试剂,在铜存在下很容易与 3-溴吡啶偶联(I) 氯化物作为催化剂和 1,2-二甲基乙二胺 (DMEDA) 作为配体。随后的NaBH 4还原得到相应的乙胺,将其与3-((3,3,3-三氟丙基)硫代)丙酰氯偶联得到噻草唑草( 1 )。这种高度简洁的路线为开发可扩展的制造工艺提供了重要的基础。