DD151749A1 - PROCESS FOR THE PREPARATION OF PYRIDINE CARBONITRILES - Google Patents

Abstract

The aim of the invention is to develop a process for the preparation of 4-aryl-2,3-bis (methylthio) -pyridine-3-car-bonitriles. The pyridinecarbonitriles of the general formula in which R is an optionally alkoxy-, alkyl- or halogen-substituted phenyl radical can be prepared by reacting the butadiene dicarbonitriles of the general formula I in which R has the above meaning, with bases. These pyridinecarbonitriles can be used as organic intermediates for further syntheses. They are suitable for the preparation of a whole range of other pyridine derivatives.

Description

-λ- 2 2 2 19 8

Process for the preparation of pyridinecarbonitriles Field of application of the invention;

The invention relates to a process for the preparation of 4-aryl-2,3-bis (methylthio) -pyridine-3-carbonitriles. These pyridinecarbonitriles can be used as organic intermediates for further syntheses. They are suitable for the preparation of a whole series of further pyridine derivatives.

Characteristic of the known technical solutions

4-aryl-2,3-bis (methylthio) -p3tridin-3-carbonitriles are not yet known,

Object of the invention

The aim of the invention is to develop a process for the preparation of 4-aryl-2,3-bis (methylthio) -pyridine-3-carbonitriles.

Explanation of the essence of the invention

The pyridinecarbonitriles of the general formula II in which R is an optionally alkoxy-, alkyl- or halogen-substituted phenyl radical can be prepared by reacting the butadiene dicarbonitriles of the general formula I in which R has the above meaning, with bases organic solvents, preferably in alcohols. As bases are

22 2 198

Sodium salts of malononitrile, or cyanoacetic esters used · The reaction temperatures are from 2O ⁰ C to the boiling point of the verv / ended solvent · If necessary, stirring of the reaction mixtures require

really. The reaction times range from a few minutes to 5 hours, depending on the reaction temperatures. On cooling, the compounds II crystallize out. The yields of II can be reduced by concentration of the mother liquor or by precipitation with water

Ί0 · Purification takes place by recrystallization from alcohols.

Embodiments Example 1

2,3-bis (methylthio) -4-phenyl-pyridine-3-carbonitrile 15

0.005 mol of sodium are dissolved in 10 ml of absolute ethanol. Add 0.005 mol of malononitrile and 0.005 mol of 4,4-bis (methylthio) -2-phenyl-buta-1,3-diene-1,1-dicarbonitrile and the mixture is stirred for 5 hours at 20 ⁰ C. The precipitate is filtered off , washed with ethanol and recrystallized from ethanol.

Yield: 25 # d.Th · Melting point: 128-130 ⁰ C CHN ¹ E-MSL (CDCl _3): (T _CH 6.81 ppm

Ber. 61.73 4.44 10.28 (TSCH, 2. 56 ppm

Gef. "62.02 4.41 10.39 ⁵ _{2> 6o ppm}

Embodiment 2

2,3-bis (methylthio) -4-phenyl-pyridine-3-carbonitrile

Dissolve 0.005 mol of sodium and 0.005 mol of malononitrile in 10 ml of absolute ethanol successively, add 0.005 mol of 4,4-bis (methylthio) -2-phenyl-1,3-butadiene-1,1-dicarbonitrile, heat the reaction mixture two minutes

-3-222198

under Eückflußkühlung to boiling and allowed to "stand at 20 ⁰ C for crystallization · The precipitate is abfil-. trated and washed with ethanol. From the filtrate is obtained by precipitation with water additional product. The combined crude products is crystallized from ethanol..

Yield: 23 $ d.Th, melting point: 128-13O ⁰ C

Exemplary embodiment 3 2,3-bis (methylthio) -4-phenyl-pyridine-3-carbonitrile

0.005 mol of sodium is dissolved in 10 ml of absolute ethanol. After the addition of 0.005 mol of ethyl cyanoacetate and 0.005 mol of 4,4-bis (methylthio) -2-phenylbuta-1,3-diene-1,1-dicarbonitrile, the mixture is heated two minutes under reflux cooling, allowed to cool to 20 ⁰ C, filtered, the precipitate is washed with ethanol and from the filtrate by precipitation with T / ater another product · the combined crude products are recrystallized from ethanol yield: 30 $ theory Melting point: 128-130 ⁰ C

Embodiment 4

2,3-bis (methylthio) -4-phenyl-pyridine-3-carbonitrile

0.005 mol of sodium are dissolved in 10 ml of methanol. After the addition of 0.005 mol of methyl cyanoacetate and 0.005 niol of 4,4-bis (methylthio) -2-phenyl-buta-1,3-diene-1,1-dicarbonitrile is heated for three minutes under refluxing to boiling. After cooling to 20 ⁰ C is filtered off and washed with methanol. The precipitate is dissolved in chloroform. The insoluble matter is filtered off (is discarded), the filtrate is concentrated in vacuo and the residue is recrystallised from ethanol.

Yield: 29iS d.Th. Melting point: 128-130 ⁰ C

222198

Embodiment 5

4- (p-methoxy ~ phenyl) -2,3-bis (methylthio) pyridine-3-carbonitrile

Dissolve 0.005 moles of sodium and 0.005 mCrol of halononitrile in 10 ml of absolute ethanol, add 0.005 mol of 2- (p-methoxy-phenyl) -4,4-bis (methylthio) -buta-1,3-diene ~ 1,1- dicarbonitrile and the reaction mixture is heated to reflux for two minutes under reflux. After cooling to 20 ⁰ C is filtered off. The precipitate is washed with ethanol and recrystallized from ethanol

Yield: 18 # dO? H. Melting point: 158-160 ⁰ C

N ¹ H -IVIVR (CDClPiT ₀₁₁ 6.79 ppm

^Ber · ^{9 '27} "/ SCH, 2.55 ppm

^{Vascular 9 '38 5} ppm 2.59

Exemplary Embodiment 6

4- (p-chloro-phenyl) -2,3-bis (methylthio) pyridine-3-carbonitrile

Dissolve 0.005 mol of sodium and 0.005 mol of malononitrile in 10 ml of absolute ethanol, heated after addition of 0.005 mol of 2- (p-chloro-phenyl) -4,4-bis (methylthio) -buta-1,3-dicarbonitrile two minutes with refluxing to boiling, allowed to cool to 20 ⁰ C, filtered off and washed with ethanol. The precipitate is recrystallised from ethanol. Yield: 16% of theory Melting point: 174-177 ⁰ C

CHN ¹ H-NMR _(CDCl3) 6.86 ppm J _QE

Bex. 54.80 3.62 9.14 cT SCH, 2.59 ppm

Gef. 55.00 3.33 9.22 '2.63 ppm

Claims (2)

_ a _ 222198 claims A process for the preparation of Pyridincarbonitrilen of the general formula II, in which R for a given. when alkoxy-, alkyl- or halogen-substituted phenyl radical, characterized in that butadiendicarbonitriles of the general formula I, in which R is as defined above, are reacted with bases. 2 Method according to point 1, characterized in that as bases preferably sodium salts of the malononitrile or of cyanoacetic acid esters · For this 1 page formulas 2 2 2 19 8 - R C ^NC \ NC NC-C ' C = C CH C-SCH, II 27. ^ 1.1980 * 8,082 ^ ":