3-Bromophenylboronic acid pinacol ester is an organoboron compound characterized by a bromine substituent at the meta-position of the phenyl ring and a boronic acid protected as a pinacol ester. This protection enhances its stability and handling properties compared to the free boronic acid. The compound is a white to off-white crystalline solid with the CAS number 594823-67-3. Its primary application is as a versatile building block in organic synthesis, particularly in transition-metal-catalyzed cross-coupling reactions such as the Suzuki-Miyaura reaction. The bromine atom serves as an excellent leaving group for various coupling reactions, while the boronic ester functionality acts as the nucleophilic coupling partner. This dual functionality makes it a valuable intermediate for constructing biaryl and other conjugated systems, which are core structures in pharmaceuticals, agrochemicals, and functional materials. As a protected boronic acid derivative, it offers advantages in purification and storage. It is commonly used in the synthesis of complex molecules for research and development purposes. Standard safety precautions for handling organic compounds should be observed.