Electric Literature of 14521-80-3,Some common heterocyclic compound, 14521-80-3, name is 3-Bromo-1H-pyrazole, molecular formula is C3H3BrN2, traditional synthetic route has been very mature, but the traditional synthetic route has various shortcomings, such as complicated route, low yield, poor purity, etc, below Introduce a new synthetic route.
General procedure: In a150 mL pressure vessel, a suspension of 3-bromo-1H-pyrazole (8 g, 54.43 mmol) cesiumcarbonate (53.2 g, 163.29 mmol), and difluoroiodomethane (10% wt. in THF, 200 ml, 106.23mmol) was heated at 45C overnight. The reaction mixture was cooled to room temperature andthen filtered through Celite. The filter cake was washed with Et20 (3 x 150 mL). The filtrate was washed with brine, dried over sodium sulfate and carefully concentrated (20 C bath, 100 mb vacuum) to give 17 g of a 1.5:1 ratio of regioisomers and solvent still present. This crude material was combined with 3,5-Difluoro-4-formylphenylboronic acid (12.65 g, 68.03 mmol),Palladium acetate (0.31 g, 1.381 mmol), butyldi- 1 -adamantylphosphine (1.171 g, 3.265 mmol) and Potassium carbonate (22.80 g, 164.96 mmol) in dioxane (150 mL) and water (50 mL) the mixture was degassed for 10 mm with argon, then heated at 100 C overnight. The reaction mixture was cooled to room temperature, concentrated under reduce pressure, the residue was diluted with EtOAc and washed with brine 2x then dried over Na2504, filtered and concentratedunder reduced pressure. The crude residue was purified by silica column chromatography (5% to15% EtOAc/Hex). Mixed fractions were recrystallized (5:1 Hex/EtOAc) combined pure product afforded P4. 1HNMR (400 MHz, Chloroform-d) oe 10.35 (d, J = 1.0 Hz, 1H), 7.92 (d, J = 2.8 Hz, 1H), 7.46 (d, J = 9.6 Hz, 2H), 7.24 (t, J = 60.5 Hz, 1H), 6.80 (d, J = 2.8 Hz, 1H).
These compound has a wide range of applications. It is believed that with the continuous development of the source of the synthetic route 3-Bromo-1H-pyrazole, its application will become more common.