SU454207A1 - The method of obtaining 2-bromo-3-aminopyridine or its derivative in the amino group - Google Patents

Description

one

The invention relates to the coupling of compounds that can be used as moon products in the synthesis of biologically active substances.

A known method for the preparation of 2-bromo-3-aminopyridine is that 2-bromo-3-nitroiiridine is reduced, which in turn is obtained from several stages: iiridine amiation, 2-oxydiiridine diazotiry turn into 2-oxyiridine, nitration 2-hydroxychemide and the effect on 2-hydroxy-3-nitropyridine phosphorus bromide. The yield of the target product in the calculation of readily available pyridine does not exceed 3.8%. The yield of derivatives in the amino group is even lower.

The known method for the preparation of 2-bromo-3-aminopyridine or its derivatives by the amio group is characterized by a multistep process and a low yield of the desired product.

The proposed method allows a reduction in the number of stages, an increase in the yield of the target product, and consists in the fact that 2-nitro-3-amino-iridine or its amino group is reacted with hydrobromic acid when heated, preferably at the boiling point of the reaction mass, in the presence of urea.

The starting 2-nitro-3-aminoprpdine or its derivative by the amino group is obtained from nicotinic acid by its conversion into 3-ethoxycarbonplaminopyridine followed by nitration of the latter and, if it is necessary to have a free amino acid, by alkaline hydrolysis of 2-pitro-3-ethoxycarbonylaminopyridine. The yield of the target product in terms of nicotinic acid is 25-39%.

The introduction of urea into the reaction mixture in a number of cases helps to increase the yield and purity of the target product.

Example 1. 3-Ethoxycarbonnlamino - 2 bromopyridine. 5 g (0.023 mol) of 3-ethoxpcarbonylamino-2-nitropyridine and 10 ml of hydrobromic acid are boiled until they separate, then evaporated, 4 ml of water are added, added with soda, extracted with ether, dried with anhydrous sodium sulfate, the ether is distilled off, filtered, washed with ether, the ether is distilled off and the residue is distilled in vacuum at 129-131.5 ° C / 7 mm Hg. Art. , get 3-ethoxycarbonylamino-2brompridin 3.4 g (yield 55%).

Paideno: N 11.21, 11.33. CsHgNaOsBr. Calculated: N 11.47.

3-amino-2-brominridpn. 0.6 g (0.0025 mol) of 3-ethoxycarbonyl-2-bromiridine is dissolved in a solution of 0.35 g of potassium hydroxide in 1 ml of water and 3 ml of ethanol. The mixture is boiled for 2 hours, evaporated and extracted with benzene. Obtain 0.15 g (45%), crystallized from n-hexane, so pl. 8GS.

Found: N 16.24, 16.28.

CsHsNoBr.

Calculated: N 16,19.

Example 2. Z-amino-2-bromiiridin.

A mixture of 0.39 g (0.003 mol) of 3-amino-2-nitropyridine, 0.36 g (0.006 mol) of urea and 5 ml of hydrobromic acid is boiled for 7 hours, evaporated, 2 ml of water are added, neutralized with soda, and extracted benzene, dried with anhydrous sodium sulfate, get 0.25 g (yield 53%) with so pl. 8GS from n-hexane.

Subject invention

Claims (3)

1. A method of producing 2-bromo-3-aminopyridine or its derivative in the amino group, characterized in that, in order to increase the yield of the target product and simplify the process, 2-nitro-3-aminopyridine or its derivative in the amino group is reacted with hydrobromic acid when heated. 2. Method I, distinguished by the fact that the process is dried at the boiling point of the reaction mass. 3. The method according to claim 1, wherein the process is carried out in the presence of urea.