Continuous-Flow Photobromination/Debromination Cascade for Synthesis of the Trifloxystrobin Intermediate

Abstract

Bromination reactions involving bromine monomers tend to be polybrominated, resulting in poor product selectivity and subsequent separation difficulties. This proposal outlines a multistep cascade for continuous flow synthesis involving photobromination and debromination. The process comprises five units: bromine generation, photobromination, quenching, water/oil separation, and photodebromination. A full-process continuous and efficient synthesis of the trifluorostrolibin intermediate (E)-Methyl-2-(2-broMoMethylphenyl)-2-MethoxyiMinoacetate (MBPA) was achieved. This process converts the byproduct (E)-Methyl-2-(2-dibroMoMethylphenyl)-2-MethoxyiMinoacetate into the target product MBPA. At a total residence time of 12.9 min, the conversion of (E)-Methy-2-(methoxyimino)-2-(o-toly) acetate reached 99.0%, and the total yield of MBPA reached 94.2%. Machine learning and quantum chemical calculations enhance the comprehension of photodebromination mechanisms. Simultaneously, through comprehensive simulations involving sensitivity and scenario analyses, the optimization of photon utilization emerged as a pivotal factor for improving the overall applicability of the production process. This method of synthesizing halogenated products is anticipated to play a crucial role in pharmaceuticals or pesticides.