Background technology:
2-chloro-5-fluoro-nicotinic acid is the pharmaceutical intermediate of outbalance, but do not have effective synthetic method so far and prepare this product, once two kinds of preparation methods had been reported in the document, a kind of method is with 2,6-two chloro-5-fluoro-Nikithans at first react with thiomethyl alcohol, thereafter be that catalyst hydrogenation is taken off the first sulfydryl and obtained 2-chloro-5-fluoro-Nikithan with the Raney's nickel, again hydrolysis obtain 2-chloro-5-fluoro-nicotinic acid (J.Med.Chem.1993,2678-2688); Another kind method is from 2-hydroxyl-nicotinic acid, nitrated chloro again gets 2-chloro-5-nitro-nicotinic acid earlier, it obtains 2-chloro-5-amino-nicotinic acid by iron powder reducing, and 2-chloro-5-amino-nicotinic acid obtains 2-chloro-5-fluoro-nicotinic acid (EP0634413A1) after the heating of gained NITRODIAZONIUM FLUOROBORATE after the diazotization in fluoroboric acid.
Document synthetic route 1:
Document synthetic route 2:
In document synthetic route 1, the one, must replace 2 with the thiomethyl alcohol of foreign odor, 6-two chloro-5-fluoro-Nikithans, take off the first sulfydryl with Raney's nickel for the catalyst hydrogenation selectivity simultaneously, yield has only about 30%, and the model of this reaction pair Raney's nickel is had relatively high expectations, and can not get product with general Raney's nickel; And document synthetic route 2 synthesis techniques are long, and last NITRODIAZONIUM FLUOROBORATE heating fluoro-reaction yield is low excessively, and not easy to operate.
We had also once developed a kind of technology of following selectivity dechlorination, and applied for Chinese invention patent (application number: 200310108336.1):
Though this technology is effectively more than the existing technology of document, and avoid using the thiomethyl alcohol of foreign odor; Shorten the route of existing synthesis technique, improve yield, reduce cost.This technology is synthetic comparatively effective for 2-chloro-5-fluoro-nicotinate, but low excessively to 2-chloro-5-fluoro-nicotinic acid synthetic population yield, and the demand pole chromatography purification, and it is small-scale synthetic that it is suitable for the laboratory, can't suitability for industrialized production.
Summary of the invention:
The technical issues that need to address of the present invention are: solved the problem that needs chromatography purification among the existing 2-chloro-5-fluoro-nicotinic acid preparation technology; Shorten the route of existing synthesis technique, improve overall yield, reduce cost, be suitable for large-scale production; Avoid using the thiomethyl alcohol of foreign odor; A kind of industrialized process for preparing of 2-chloro-5-fluoro-nicotinic acid is provided.
Technical scheme of the present invention:
The present invention with conventional, be easy to get 2,6-two chloro-5-fluoro-nicotinic acid are raw material, slough 2 earlier by catalytic hydrogenation method, two chlorine atoms on the 6-two chloro-5-fluoro-nicotinic acid, and then the nitrogen oxidation, the nitrogen oxidation 5-fluoro-nicotinic acid that obtains obtains 2-chloro-5-fluoro-nicotinic acid after handling with chlorizating agent.
Concrete synthesis technique of the present invention is as follows:
In above-mentioned technological process, we adopt the method for direct catalytic hydrogenation to 2, and 6-two chloro-5-fluoro-nicotinic acid are sloughed two chlorine.Auxiliary addition agent is selected triethylamine for use.Catalyzer adopts conventional hydrogenation catalyst, and as Raney's nickel, palladium carbon etc., the reaction consumption is 1~10% (W/W) of reaction substrate, and solvent is an ethanol, methyl alcohol, ethyl acetate etc.; Reaction pressure is a 1-10 normal atmosphere, and optimal pressure range is between 1~5 normal atmosphere; Temperature of reaction is a normal temperature to 100 ℃, and optimum temps is 20~50 ℃.
In 5-fluoro-nicotinic acid nitrogen oxidising process, we select oxygenant commonly used, that be easy to get for use, as hydrogen peroxide, and Peracetic Acid, peroxidation m-chlorobenzoic acid etc., the nitrogen oxidation solvent is acetic acid, methylene dichloride etc., temperature is a normal temperature to 120 ℃.
Then, nitrogen oxidation 5-fluoro-nicotinic acid is carried out the selectivity chlorination, chlorizating agent adopts phosphorus oxychloride, reagent such as phosphorus pentachloride, and temperature of reaction is 50-120 ℃.
Beneficial effect of the present invention:
Reaction process of the present invention is selected rationally; it has adopted and has been easy to get, the raw material-2 of energy large-scale production; 6-two chloro-5-fluoro-nicotinic acid through dechlorination, nitrogen oxidation more optionally chloro get 2-chloro-5-fluoro-nicotinic acid; its overall yield reaches 50~60%; and all intermediates can be purified by recrystallization, therefore can carry out industrialized production on a large scale.
Embodiment:
The following example helps to understand the present invention, but is not limited to content of the present invention.
Embodiment 1
Synthetic (the POCl of 2-chloro-5-fluoro-nicotinic acid
3, 50 ℃, 12h)
The first step; Synthesizing of 5-fluoro-nicotinic acid
2, (100g, (101.0g, 1.0mol) and 5% palladium-carbon catalyst (4g), hydrogenation is 12 hours under 3 normal atmosphere, room temperature to add triethylamine in ethanol solution 0.476mol) (2.4L) for 6-two chloro-5-fluoro-nicotinic acid.Remove by filter catalyzer, concentrate, product (66.2g, 0.468mol), productive rate: 98%.
1H?NMR(400MHz,DMSO-d
6):δ8.91(s,1H),8.81(d,J=2.8Hz,1H),8.09(dd,J=8.8&2.8Hz,1H);Ms(M
++1,142)。
Second step: nitrogen oxidation-5-fluoro-nicotinic acid synthetic
(50g 0.36mol) is dissolved in (500mL) in the Glacial acetic acid to 5-fluoro-nicotinic acid, adds 30%H
2O
2(74mL 0.72mol), is heated to 100 ℃, and reaction is spent the night, the pressure reducing and steaming Glacial acetic acid, the washing, product (53g, 0.34mol), productive rate: 95%.
1H?NMR(400MHz,DMSO-d
6):δ8.75(d,J=2.8Hz,1H),8.37(s,1H),7.68(dd,J=8.4&2.8Hz,1H);Ms(M
++1,158)。
The 3rd step: the synthetic (POCl of 2-chloro-5-fluoro-nicotinic acid
3, 50 ℃, 12h)
(10g 63.7mmol) is dissolved in POCl to nitrogen oxidation-5-fluoro-nicotinic acid
3(70mL), be heated to 50 ℃, stir 12h, pressure reducing and steaming POCl
3, add trash ice, stir, separate out light brown solid, filter, crude product (11g), the water as solvent recrystallization, pure product (6.4g, 36.5mmol), productive rate: 57%.
1H?NMR(400MHz,DMSO-d
6):δ8.60(d,J=2.8Hz,1H),8.18(dd,J=8.4&2.8Hz,1H);Ms(M
++1,176,178)。
Embodiment 2
Synthesizing of 2-chloro-5-fluoro-nicotinic acid
2, (50g, (50.5g, 0.5mol) and Raney's nickel catalyst (5g), hydrogenation is 12 hours under 5 normal atmosphere, room temperature to add triethylamine in ethanol solution 0.238mol) (1.2L) for 6-two chloro-5-fluoro-nicotinic acid.Remove by filter catalyzer, concentrate, product (32.8g, 0.232mol), productive rate: 97%.
In the process of preparation 2-chloro-5-fluoro-nicotinic acid, prepare corresponding product according to second step, the 3rd described nitrogen oxidation of step and chloro processing condition and operation steps in the above-mentioned example 1, its test data is shown in above-mentioned example 1.
Embodiment 3
Synthetic (the POCl of 2-chloro-5-fluoro-nicotinic acid
3+ PCl
5, 70 ℃, 12h)
According to the first step, described reaction conditions of second step and working method in the above-mentioned example 1, prepare nitrogen oxidation-5-fluoro-nicotinic acid intermediate.Then, (10g 63.7mmol) is dissolved in POCl with nitrogen oxidation-5-fluoro-nicotinic acid
3(50mL), under the ice bath, add PCl
5, (20g) be heated to 50 ℃, stir 12h, pressure reducing and steaming POCl
3, add the 50g trash ice, stir, separate out light brown solid, filter, crude product 11g, the water recrystallization, pure product (6.7g, 38.2mmol), productive rate: 60%.
Embodiment 4
Synthetic (the POCl of 2-chloro-5-fluoro-nicotinic acid
3, 110 ℃, 5h)
According to the first step, described reaction conditions of second step and working method in the above-mentioned example 1, prepare nitrogen oxidation-5-fluoro-nicotinic acid intermediate.Then, (10g 63.7mmol) is dissolved in POCl with nitrogen oxidation-5-fluoro-nicotinic acid
3(70mL), stir, be heated to backflow 5h, pressure reducing and steaming POCl
3, add trash ice, stir, separate out light brown solid, filter, crude product (10.5g), the water recrystallization, pure product (6.7g, 38.2mmol), productive rate: 60%
Embodiment 5
Synthetic (the POCl of 2-chloro-5-fluoro-nicotinic acid
3+ PCl
5, 110 ℃, 5h)
According to the first step, described reaction conditions of second step and working method in the above-mentioned example 1, prepare nitrogen oxidation-5-fluoro-nicotinic acid intermediate.Then, (10g 63.7mmol) is dissolved in POCl with nitrogen oxidation-5-fluoro-nicotinic acid
3(70mL), stirring and dissolving adds PCl in batches under the ice bath
5(15g), be heated to backflow 5h, add trash ice, stir, separate out light brown solid, filter, crude product (11g), the water as solvent recrystallization, pure product (7.5g, 42.7mmol), productive rate: 67%.
Embodiment 6
Synthetic (the POCl of 2-chloro-5-fluoro-nicotinic acid
3+ PCl
5, 110 ℃, 5h, large scale)
According to the first step, described reaction conditions of second step and working method in the above-mentioned example 1, prepare nitrogen oxidation-5-fluoro-nicotinic acid intermediate.Then, (500g 3.18mol) is dissolved in POCl with nitrogen oxidation-5-fluoro-nicotinic acid
3(2000mL), stirring and dissolving adds PCl in batches under the ice bath
5(700g), be heated to backflow 5h, pressure reducing and steaming POCl
3, add trash ice, stir, separate out light brown solid, filter, crude product (545g), the water recrystallization, pure product (362g, 2.06mol), productive rate: 65%.
Embodiment 7
Synthesizing of 2-chloro-5-fluoro-nicotinic acid
2, catalyzer is a Raney's nickel in the 6-two chloro-5-fluoro-nicotinic acid catalytic hydrogenations, and consumption is 8.0 grams, and solvent is selected ethyl acetate for use, and reaction pressure is 7 normal atmosphere, and temperature of reaction is 60 ℃; In 5-fluoro-nicotinic acid nitrogen oxidising process, oxygenant is selected Peracetic Acid for use, and reaction solvent is a methylene dichloride, and temperature of reaction is 60 ℃; Then, nitrogen oxidation 5-fluoro-nicotinic acid is carried out the selectivity chlorination, chlorizating agent adopts phosphorus pentachloride, and temperature of reaction is 80 ℃, and all the other are identical with embodiment 1.
Embodiment 8
Synthesizing of 2-chloro-5-fluoro-nicotinic acid
2, reaction solvent is selected methyl alcohol for use in the 6-two chloro-5-fluoro-nicotinic acid catalytic hydrogenations, and reaction pressure is 4 normal atmosphere, and temperature of reaction is 40 ℃; In 5-fluoro-nicotinic acid nitrogen oxidising process, oxygenant is selected the peroxidation m-chlorobenzoic acid for use, and reaction solvent is a methylene dichloride, and temperature of reaction is 80 ℃; Then, nitrogen oxidation 5-fluoro-nicotinic acid is carried out the selectivity chlorination, temperature of reaction is 60 ℃, and all the other are identical with embodiment 1.