E-Phenylethenylboronic acid

Chemical Properties

Brown granular powder

Uses

Reagent used for

• Palladium (Pd)-catalyzed Suzuki-Miyaura coupling reactions
• Rhodium (Rh)-catalyzed intramolecular amination of aryl azides
• Diastereoselective synthesis via Pd-catalyzed Heck-Suzuki cascade reaction
• Copper (Cu)-mediated cyanation
• Rhodium (Rh)-catalyzed asymmetric addition
• Diastereoselective synthesis via iridium (Ir)-catalyzed addition
• Palladium (Pd)-catalyzed cascade cyclization

Reagent used in Preparation of

• Optically active unsaturated amino acids by diastereoselective Petasis borono-Mannich reaction
• Amino alcohol dienes via Petasis 3-component reaction using Ru-catalyzed ring-closing metathesis and isomerization

Uses

E-Phenylethenylboronic acid is a reagent used for• ;Palladium (Pd)-catalyzed Suzuki-Miyaura coupling reactions
1 Rhodium (Rh)-catalyzed intramolecular amination of aryl azides
2 Diastereoselective synthesis via Pd-catalyzed Heck-Suzuki cascade reaction
3 Copper (Cu)-mediated cyanation
4 Rhodium (Rh)-catalyzed asymmetric addition
5 Diastereoselective synthesis via iridium (Ir)-catalyzed addition
6 Palladium (Pd)-catalyzed cascade cyclization
7 Reagent used in Preparation of • ;Optically active unsaturated amino acids by diastereoselective Petasis borono-Mannich reactio

Uses

trans-beta-Styrylboronic acid as reagent is used for palladium (Pd)-catalyzed Suzuki-Miyaura coupling reactions, diastereoselective synthesis via Pd-catalyzed Heck-Suzuki cascade reaction and rhodium (Rh)-catalyzed intramolecular amination of aryl azides. It is also used as reagent in preparation of optically active unsaturated amino acids by diastereoselective Petasis borono-Mannich reaction and amino alcohol dienes via Petasis 3-component reaction using Ru-catalyzed ring-closing metathesis and isomerization.

Synthesis

The general procedure for the synthesis of trans-BETA-styrene boronic acid from (E)-(2-bromovinyl)benzene is as follows: in a 50 mL round-bottomed flask (equipped with a side arm, condenser, and stirring bar) triphenylphosphine (0.131 g, 0.5 mmol, 20 mol%), p-iodoanisole (0.585 g, 2.5 mmol), and triethylamine (1.78 mL. 12.5 mmol). The reaction system was degassed three times by alternating vacuum and argon filling. Palladium dichloride (0.023 g, 0.13 mmol, 5 mol%) was added under positive argon atmosphere. After stirring for 15 minutes at room temperature, diisopropylaminoborane (5 mL, 1 M THF solution, 5 mmol) was added and the reaction mixture was again degassed three times by alternating vacuum and argon filling. The reaction mixture was heated to reflux and kept at reflux for 12 hours. Upon completion of the reaction, the reaction solution was cooled to 0 °C, and 6 mL of methanol was slowly added (note: this process is an exothermic reaction accompanied by hydrogen release). Stirring was continued for 15 minutes and then concentrated under reduced pressure to remove all solvent to give a black solid. The solid was dissolved in 3M sodium hydroxide solution (8 mL) and subsequently washed with hexane (3 x 10 mL). The aqueous phase was cooled to 0°C (ice bath) and acidified with concentrated hydrochloric acid to pH ≤ 1, at which point the boric acid precipitated as a white solid. The aqueous phase was extracted with ether (3 x 10 mL), the organic phases were combined, dried with magnesium sulfate and filtered. Finally, the solvent was removed by concentration under reduced pressure to obtain the target product, trans-BETA-styrene boronic acid, as a white solid.

References

[1] Tetrahedron, 2011, vol. 67, # 3, p. 576 - 583