5-Formyl-2-methylphenylboronic acid pinacol ester

Name: 5-Formyl-2-methylphenylboronic acid pinacol ester 

Molecular Formula: C14H19BO3 

CAS#: 847560-50-3 

SMILES: CC1=CC=C(C=O)C=C1B2OC(C)(C)C(C)(C)O2 

MDL#: MFCD18731017 

Catalog#: F36226 

Molecular weight:   246.11 g/mol 

Other names: 

• Name 1: (5-Formyl-2-methylphenyl)boronic acid pinacol ester 

• Name 2: 4-Methyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzaldehyde 

Fields of Interest: Organic synthesis, Suzuki coupling reactions 

Background & Applications: 5-Formyl-2-methylphenylboronic acid pinacol ester is an organoboron compound featuring a boronic ester group, a formyl (aldehyde) group, and a methyl substituent on an aromatic ring. The pinacol ester moiety enhances the compound’s stability compared to its corresponding boronic acid, making it more amenable to storage and handling in synthetic applications. However, like other pinacol boronic esters, it remains sensitive to hydrolysis, especially under aqueous conditions, necessitating careful handling during reactions and storage. 

Applications: 

5-Formyl-2-methylphenylboronic acid pinacol ester serves as a versatile intermediate in organic synthesis. The aldehyde group allows for further functionalization through reactions such as reductive amination or condensation, while the boronic ester group is pivotal in cross-coupling reactions, notably the Suzuki–Miyaura coupling, facilitating the formation of carbon–carbon bonds. Additionally, boronic esters have been employed in the development of fluorescent probes for detecting reactive oxygen species and metal ions in biological systems. 

Appearance: White solid 

Purity: 98% 

Storage: 3-5 °C 

Solubility: Ethyl acetate, Dichloromethane, chloroform, Diethyl ether 

Literature: 

Clausen, F., Kischkewitz, M., Bergander, K., & Studer, A. (2019). Catalytic protodeboronation of pinacol boronic esters: formal anti-Markovnikov hydromethylation of alkenes. Chemical Science, 10(24), 6210–6214. https://doi.org/10.1039/c9sc02067e 

Dai, L., Gonzalez, J., & Zhang, K. (2022). A simple generic method for analyzing water sensitive pinacol boronate compounds by hydrophilic interaction liquid chromatography. Journal of Chromatography Open, 2, 100036. https://doi.org/10.1016/j.jcoa.2022.100036 

Lennox, A. J. J., & Lloyd-Jones, G. C. (2013). Selection of boron reagents for Suzuki–Miyaura coupling. Chemical Society Reviews, 43(1), 412–443. https://doi.org/10.1039/c3cs60197h 

Zhong, Q., Ngim, K. K., Sun, M., Li, J., Deese, A., & Chetwyn, N. P. (2012). Strategies for the analysis of highly reactive pinacolboronate esters. Journal of Chromatography A, 1229, 216–222. https://doi.org/10.1016/j.chroma.2012.01.050 

Achilli, C., et al. (2013). Susceptibility to hydrolysis of phenylboronic pinacol esters at physiological pH. Central European Journal of Chemistry, 11, 137–139. 

Sandford, C., & Aggarwal, V. K. (2014). Selection of boron reagents for Suzuki–Miyaura coupling. Chemical Society Reviews, 43(1), 166–178.