The polar and often amphiphilic character of boronic acids tends to make their isolation and purification difficult. In addition to these potential difficulties in isolating boronic acids, their tendency to form oligomeric anhydrides further complicates characterization efforts. To palliate to these problems, boronic acids are often purified and characterized as boronic esters. Boronic acids are also best handled as ester derivates in case of difficulty in measuring accurate and reproducible melting points for free boronic acids.
For reasons of simplification, the pinacol ester of pyridine-3-ylboronic is called pyridine-3-boronic acid pinacol ester instead of its formal name 3-(4,4,5,5-Tetramethyl-[1,3,2]dioxaborolan-2-yl)-pyridine.
Advantages of boronic esters
Main benefits of the use of boronic esters in Suzuki-Miyaura cross-couplings
Additional applications of boronic esters
A number of chiral boronic esters, such as the ones illustrated below, have been used as inducers in stereoselective reactions.
Advantages of these boronic esters