Recent Progress in the Preparation of Organoboron Reagents via Direct Borylations

Abstract

Recent progress in the preparation of organoboron reagents for cross-coupling reactions is described. Organoboron reagents are versatile synthons in Suzuki-Miyaura coupling. A common method for the synthesis of organoboron reagents is the borylation of aryl or vinyl magnesium (or lithium) intermediates that are produced from aryl or vinyl halides. In addition to these traditional methods, the direct borylation of aromatic and heteroaromatic compounds has also been recently reported as a more atom-economical method. We describe our new homogeneous and heterogeneous catalysts for aromatic C-H borylation. Regarding the heterogeneous catalyst, the recovered catalyst could be reused without a loss of activity. We developed this heterogeneous batch reaction system into a continuous-flow reaction system using a column field with our heterogeneous catalyst.