Phenoxy-Dialkoxy Borates as a New Class of Readily Prepared Preactivated Reagents for Base-Free Cross-Coupling

One of the most useful chemical transformations of organoboronic acids is the Suzuki-Miyaura cross-coupling reaction. Although it has vast application, it possesses some limitations: boronic acids can be difficult to quantify accurately due to their tendency to form oligomeric anhydrides and they must be activated under basic conditions. To address these problems, a new class of boronic acid derivatives is described. Phenoxy-dialkoxy borates are prepared under mild conditions and show good solubility in common organic solvents. These adducts can be used in base-free metal-catalysed cross-coupling reactions, including orthogonal reactions with MIDA boronates and trifluoroborates.