Diethanolamine Boronic Esters: Development of a Simple and Standard Process for Boronic Ester Synthesis

Herein, we disclose the unique physical properties of diethanolamine (DEA) boronic esters that have facilitated the development of a simple and standard process for their synthesis and isolation using environmentally sustainable solvents. Moreover, their preparation is facile, robust, and scalable and can be telescoped from a solution of boronic acid or boronic ester via esterification/transesterification with DEA, therefore providing wide access from a plethora of reaction types. To date, AstraZeneca has successfully manufactured three DEA boronic esters at the kilogram scale (5, 50, and 100 kg batches), with plans to expand this to more examples in 2020.