Boronester

Boronester is a term used in chemistry to describe compounds in which boron is covalently bonded to oxygen atoms within organic substituents. In practice, the word is most often encountered as a shorthand for boron esters, including boronic esters of the form RB(OR')2 and boronate esters formed from boronic acids and diols. Because "boronester" is not a single standardized name, its exact scope varies among sources; some use it as a broad synonym for boronic and boronate esters, while others reserve it for specific chelated B–O structures.

Chemistry and preparation: Boronate esters are typically prepared by reaction of boronic acids with diols to give cyclic boronates (for example, pinacol boronate esters) or by transesterification of existing boron esters with different alcohols. They tend to be more stable toward air and moisture than the parent boronic acids, although many remain moisture-sensitive and hydrolyze to liberate boronic acids under aqueous conditions.

Applications: boron esters are widely used in organic synthesis as masked or protected boron reagents. They enable Suzuki–Miyaura cross-coupling and other transformations where a boron partner is desired but boronic acid handling is problematic. They also serve as building blocks in materials chemistry and as protecting groups for boron-containing substrates. Notable examples include the pinacol boronate ester (B(pin)) and MIDA boronates, which offer different balances of stability and reactivity.

History and terminology: The term "boronester" has appeared in older and some non-standard texts; in contemporary literature, "boronic ester" and "boronate ester" are preferred for clarity.