2-Propenoic acid, 3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-, ethyl ester, (2E)- also known as Ethyl (E)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane-2-carboxylate, is a chemical compound that serves as an important reagent in organic synthesis, particularly in the transition metal-catalyzed cross-coupling reactions such as Suzuki-Miyaura coupling.

The Suzuki-Miyaura coupling is a widely used reaction in the field, enabling the formation of carbon-carbon bonds by coupling aryl or vinyl boronic acids (or their esters) with aryl or vinyl halides or triflates in the presence of a palladium catalyst. The ethyl 2-propenoate moiety of the compound can act as a vinyl source, which upon coupling with an appropriate partner can introduce a substituent into an aromatic or vinyl backbone. This is particularly useful for the synthesis of highly complex organic molecules, including pharmaceuticals, agrochemicals, and OLEDs (organic light-emitting diodes) materials.

What sets apart reagents like the ethyl ester of dioxaborolane is their enhanced stability and ease of handling compared to their boronic acid counterparts. This stability is largely due to the coordination of the boron atom within the dioxaborolane ring, making these reagents less susceptible to hydrolysis and oxidation. Furthermore, they often show increased reactivity under milder conditions, which offers a broader substrate scope and can improve the yields of the desired products.

The application of ethyl (E)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane-2-carboxylate is not limited to cross-coupling reactions; it also finds utility in various other synthetic transformations which capitalize on the unique reactivity of the incorporated boron moiety. For instance, this versatility includes its use in homologation reactions, where the compound acts as a precursor for the introduction of extended alkyl chains or functional moieties, thus further diversifying the toolkit available to synthetic chemists.