Background and overview of the preparation method of 5-isopropylpyridin-2-amine
5-Isopropylpyridin-2-amine can be used as a pharmaceutical synthesis intermediate. If 5-isopropylpyridin-2-amine is inhaled, move the patient to fresh air; if there is skin contact, take off contaminated clothing, wash the skin thoroughly with soap and water, and seek medical attention if you feel unwell; if In case of eye contact, separate eyelids, rinse with running water or saline, and seek medical attention immediately; if ingested, rinse mouth immediately, do not induce vomiting, and seek medical attention immediately.
Preparation method of 5-isopropylpyridin-2-amine
The preparation of 5-isopropylpyridin-2-amine is divided into the following two steps:
Step 1: 5-(prop-1-en-2-yl)pyridin-2-amine. To a stirred and degassed solution of 5-bromopyridin-2-amine (3.5 g, 20.34 mmol) in aqueous 1,4-dioxane (1:1, 40 mL) was added potassium phosphate (12.94 g, 61.04 mmol), and Continue degassing for 10 minutes. Then, 4,4,5,5-tetramethyl-2-(prop-1-en-2-yl)-1,3,2-dioxaborolane (5.21g, 30.51mmol), Then [1,2-bis(diphenylphosphino))ferrocene] was added with palladium(II) dichloride (1.47 mg, 2.014 mmol), degassed under stirring for 10 minutes and heated to 100°C for 2 hours. . The reaction mixture was cooled to room temperature and filtered through a pad of Celite. Add cold water to the filtrate and extract with ethyl acetate (3 × 200 mL). The organic layer was washed with water (2 × 100 mL), brine (100 mL), dried over sodium sulfate and concentrated. The resulting residue was purified by column chromatography on silica gel (100-200 mesh), eluting with 40% ethyl acetate in petroleum ether, to give 5-(prop-1-en-2-yl)pyridin-2-amine (2.5 g, 18.65 mmol, yield 91%) as a brown solid. MS (ESI) m/z135.18[M+1]+.
Step 2: 5-isopropylpyridin-2-amine. To a slurry of 20% palladium hydroxide (1 g) in ethyl acetate (50 mL) was added 5-(prop-1-en-2-yl)pyridin-2-amine (2.5 g, 18.65 mmol) and stirred at room temperature. Hydrogen balloon (1 arm) for 2 hours. The reaction mixture was filtered through a pad of celite, dried over sodium sulfate and concentrated to give 5-isopropylpyridin-2-amine (2 g, 14.70 mmol of trifluoromethoxypyridine, 79% yield) as a brown liquid. MS (ESI) m/z137.15[M+1]+.
Main reference materials for the preparation method of 5-isopropylpyridin-2-amine
[1] WO2016007848 ANTIPROLIFERATIVE COMPOUNDS ASODIUM CARBONATEND METHODS OF USE THEREOF
