4-Hydroxyphenylboronic acid N-methyliminodiacetic acid (MIDA) ester is a protected boronic acid derivative used primarily in organic synthesis and bioconjugation applications. The MIDA group provides stability to the boronic acid, facilitating handling and storage while allowing selective deprotection under mild conditions. Upon deprotection, the resulting 4-hydroxyphenylboronic acid exhibits high affinity for cis-diols, enabling specific binding to carbohydrates such as glucose, fructose, and glycoproteins. This property makes it valuable for developing non-enzymatic biosensors for sugar detection, including glucose monitoring in diabetes management. It is also employed in targeted drug delivery systems, particularly for directing therapeutics to cancer cells with elevated surface glycans or sialic acids. Additionally, it serves as an intermediate in the synthesis of complex organic molecules, including those involving carbon-carbon bond formation via Suzuki-Miyaura coupling after deprotection.