Product manager: Emma Song Email: emma@coreychem.com
The English name of cyclopropylboronic acid pinacol ester is Cyclopropylboronic acid pinacol ester, with the molecular formula of C₉H₁₇BO₂.
Its appearance is a colorless liquid. It is sensitive to moisture and should be stored in an inert atmosphere.
Its molecular structure contains a cyclopropyl group (Cyclopropyl), which is a three-membered carbon ring, and a pinacol ester group (Pinacol ester group), where the boron atom is connected to the pinacol alcohol part through two oxygen atoms.
The pinacol alcohol part is a 1,3,2-dioxaboraboraphenylcyclopentane with tetramethyl substitution. It has strong reactivity.
Application
In a nitrogen atmosphere, 1,4-dioxane (4.3 mL) solution of the compound 82-2 (200 mg) was added to the mixture of cyclopropylboronic acid furanate (215 mg), 2N potassium phosphate aqueous solution (1.28 mL), and XPhos-Pd-G2 (50 mg), and the mixture was stirred at 100°C for 2 hours.
Additionally, 107 mg of cyclopropylboronic acid furanate, 0.64 mL of 2N potassium phosphate aqueous solution, and 50 mg of XPhos-Pd-G2 were added to the mixture, and the mixture was stirred at 100°C for 2 days. 1N hydrochloric acid was added to the reaction mixture, and the mixture was extracted with ethyl acetate.
The extract was washed with saturated brine and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure.
The resulting residue was purified by silica gel column chromatography (hexane:ethyl acetate = 70:30 – 40:60) to obtain the crude purified product 9-(4-cyclopropylphenyl)nonanoic acid (82 mg), which is a yellow solid.
MS (ESI) m/z: 273.3 (m-H) .
Synthesis
Under nitrogen protection, the anhydrous tetrahydrofuran (THF) solution of isopropylboronic acid phthalate was slowly added to the THF solution of cyclopropyl bromide.
The addition process lasted for more than 30 minutes. After the addition was completed, the mixture was stirred at room temperature for 5 hours, then naturally heated to 25°C and stirred for another 16-20 hours.
The reaction progress was monitored by TLC. After the reaction was completed, the reaction solution was poured into a mixed solution of saturated ammonium chloride aqueous solution and ethyl acetate with a volume ratio of 1:1.
The organic phase was separated by stirring and washed with saturated salt water, dried and concentrated.
Finally, the product was purified by column chromatography to obtain the cyclopropylboronic acid phthalate.
Throughout the reaction process, the drying degree of the solvent and the inert atmosphere of the operating environment need to be strictly controlled to ensure the smooth progress of the reaction and the acquisition of high-purity products.
