An efficient process to prepare methyl 4,5,6-trichloropicolinate using Ir catalyzed C-H borylation followed by CuCl2 catalyzed chlorodeborylation was developed. The process featured extremely low loading (as low as 0.0005 equiv) of [Ir(OMe)cod]2 catalyst with outstanding reactivity and regioselectivity (&gt;150 : 1) during C-H borylation. The impurity from product dechlorination can be significantly reduced by &gt;30 fold to &lt;0.4%. The excellent reactivity and control of the protodeborylation impurity in subsequent copper catalyzed chlorodeborylation was also demonstrated. This enabled successful demonstration of a highly efficient process at 46 mmol scale with excellent overall yield (75%). Furthermore, it was showcased that the Ir catalyst and 4,4′-di-<i>tert</i>-butyl-2,2′bipyridyl (dtbpy) ligand can be directly recycled and reused after filtration of the product. All these developments would offer significant economic benefits as well as process simplification for applying Ir chemistry.

Development of an efficient process to prepare methyl 4,5,6-trichloropicolinate using highly selective C-H borylation/chlorodeborylation reactions

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

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