Application of 2075-45-8, These common heterocyclic compound, 2075-45-8, name is 4-Bromo-1H-pyrazole, its 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.
To a stirred solution of 4-bromo-pyrazole (10.44 g, 71.03 mmol) in anhydrous DMF (96 mL), cooled to 0C, was slowly added NaH (60% in mineral oil) (3.13 g, 78.133 mmol). The solution was stirred for 1 hour at 0C. 4-Methanesulfonyloxy-piperidine-1-carboxylic acid tert-butyl ester (19.82 g , 71.03 mmol) was added slowly and the reaction was heated to 100C overnight or until consumption of the pyrazole by NMR. The reaction was cooled to room temperature and water added (20 mL) followed by extraction with EtOAc. The combined extracts were washed with saturated aqueous NaCI (4 x 20 mL), dried with Na2SO4 and concentrated to afford 4-(4-bromo-pyrazol-1-yl)-piperidine-1-carboxylic acid tert-butyl ester as an orange oil. The oil was purified using silica gel chromatography eluting with 10% EtOAc/hexanes to 25% EtOAc/hexanes to provide 4-(4-bromo-pyrazol-1-yl)-piperidine-1-carboxylic acid tert-butyl ester as a white solid (10.55 g, 45% yield) with a R^= 0.4 (25% EtOAc/hexanes, using iodine as the stain). 1H NMR (CDCI3, 400 MHz) 8 7.46 (s, 1H), 7.43 (s, 1H), 4.23 (m, 3H), 2.88 (m, 2H), 2.10 (m, 2H), 1.88(m, 2H), 1.47(s, 9H).
Statistics shows that 4-Bromo-1H-pyrazole is playing an increasingly important role. we look forward to future research findings about 2075-45-8.
Reference:
Patent; PFIZER INC.; WO2006/21881; (2006); A2;,
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics