2,3-DIAMINOACRYLONITRILE DERIVATIVES

Abstract: 2,3-Diaminoacrylonitrile derivs. of formula (I) are new: where R is alkyl (opt. substd. by phenyl, substd. phenyl, halogen, 1-6C alkoxycarbonyl, carboxy, (1-6C alkoxycarbonyl) alkylthio, OH, SH, cycloalkyl or O-contg. heterocyclyl), alkenyl, cycloalkyl, aryl (opt. substd. by halogen, 1-6C alkyl, nitro, phenyl, substd. phenyl or phenoxy), or O or S-contg. heterocyclyl.

Description: Technical Field: The present invention relates to new 2,3-diaminoacrylonitrile derivatives where the 3-position of 2,3-diaminoacrylonitrile is substituted by alkylthio groups, arylthio groups or hetero­ cycliothio groups. The 2,3-diaminoacrylonitrile derivatives of this invention can be used as starting materials for the manufacture of pharmaceutical and/or agricultural intermediates such as cyanoimidazoles, cyanopyrazines and cyano-substituted heterocycles. They can also be used as materials for the manufacture of diaminomaleonitrile, known as a pharmaceutical intermediate. Background Art : Some of the compounds derived from hydrogen cyanide are known as useful starting materials for the manufacture of pharma­ ceutical and/or agricultural intermediates. For example, 2-­ aminomalononitrile H₂N_C(CN)₂H , a trimer of hydrogen cyanide, tetramers such as diaminomaleonitrile H₂N(CN)C=C(CN)NH₂ diiminosuccinonitrile. Of these compounds, 2-aminomalononitrile is an extremely unstable compound. Generally it exists as p-toluenesulfonate which also is so unstable that it undergoes decomposition and discoloration. Moreover, it is too expensive to be used as industrial materials. The purpose of the present invention is to provide 2,3-­ diaminoacrylonitrile derivatives, a new and stable trimer of hydrogen cyanide, which similar to 2-aminomalononitrile can be used as starting materials for the preparation of a wide variety of organic compounds. It is also aimed to provide the method of producing these derivatives at a moderate price. Disclosure of Invention : In the course of their mechanistic studies on the formation of diaminomaleonitrile by tetramerization of hydrogen cyanide, the inventors discovered stable derivatives of 2,3-­ diaminoacrylonitrile, a trimer of hydrogen cyanide, and thus have completed this invention. The present invention relates to the 2,3-diaminoacrylonitrile derivatives, or their salts, having the formula (I): (wherein R represents an alkyl group which may be substituted by (unsubstituted or substituted phenyl groups, halogen atoms, C 1-6 alkoxycarbonyl groups, carboxy groups, C 1-6 alkoxycarbonyl C 1-6 alkylthio groups, hydroxy groups, mercapto groups, cycloalkyl groups or heterocyclic groups containing oxygen atoms), an alkenyl group, a cycloalkyl group, an aryl group which may be substituted by (halogen atoms, C 1-6 alkyl groups, nitro-groups, unsubstitutcd or substituted phenyl or phenoxy groups) or heterocyclic groups containing oxygen atoms or sulfur atoms). The 2,3-diaminoacrylonitrile derivatives expressed by the general formula (I) above can normally be isolated as crystals in the form of p-toluenesulfonates, hydrochlorides or other salts. These salts are quite stable and can be purified by recrystallization or other normal methods. Further, the free compounds are comparatively stable in aprotic solvents and highly reactive polyfunctional compounds. Best Mode for Carrying Out the Invention: The 2,3-diaminoacrylonitrile derivatives having the formula (I) can be manufactured by the following methods. (1) Method where hydrogen cyanide is used (hereunder called manufacturing method "a") Reactions are allowed to proceed in an organic solvent in the presence of a base. To the reaction mixture is then added organic acids, such as oxalic acid or other organic carboxylic acids; p-­ toluenesulfonic acid, naphthalenesulfonic acid or other organic sulfonic acids; or inorganic acids such as hydrochloric acid, sulfuric acid, or phosphoric acid, to thereby isolate relevant acid salts of 2,3-diaminoacrylonitrile derivatives. For disulfides, these corresponding to the intended compounds are suitably used. Further, unsymmetrical disulfides may be used. For the solvents, acetonitrile or other polar solvents, and toluene or other nonpolar solvents may be used. Their combined use is also possible. For the base, sodium cyanide or other inorganic bases are used as well as organic bases such as triethylamine, pyridine, diazabicycloundecene (DBU) or other organic bases. The reactions are controlled under conditions where both tetramerization or polymerization are prevented. Normally these reactions are carried out at room temperature and under atmospheric pressure, though the levels of the temperature and pressure vary with the type of solvents and media used, the amount of their use, etc. The salts of 2,3-diaminoacrylonitrile derivatives isolated from reaction mixture are treated by alkali to give readily intended products in free forms. Incidentally, instead of the disulfides expressed by the general formula (II), it is also possible to allow etc. to react with hydrogen cyanide and to thereby obtain the compounds of the invention. (2) Method where 2-aminomalononitrile is used (hereunder called the manufacturing method "b"): Reactions are allowed to proceed in an organic solvent in the presence of a base. For the organic solvent and the base, the items specified for the manufacturing method "a" can be used and so can alcohols. 2-Aminomalononitrile as expressed by the formula (VI) is so unstable that normally salts of p-toluenesulfonic acid, etc. are used. After the reactions are completed the similar procedures operated under the manufacturing method "a" are carried out to obtain salts or free forms of intended products. (3) Manufacturing method : In the 2,3-diaminoacrylonitrile derivatives having the formula (I), depending on the type of the substituent expressed by R, exchange reactions of (I) with R′SH shown by the following scheme, can also produce the compounds (VIII) which the invention concerns. The structure of the compound of the invention has been determined from the result of IR, NMR, MASS or other analyses. The present invention is described in more detail by using examples. The scope of the invention, however, is by no means limited by these examples. Example 1 A solution of diphenyl disulfide (1 g), triethylamine (3 g) and hydrogen cyanide (7 g) in acetonitrile (21 g) was stirred for 1 hour at room temperature. To the residue left after evaporation of the solvent, p-toluenesulfonic acid (1.5 g) was added with well stirring to give a light-yellow precipitate (2.3 g) which was collected by filtration, washed thoroughly with n-hexane and dried in vacuo. Recrystallization from acetonitrile gave white crystals: m.p. 148-149°C (dec.) Anal. Calcd for C 16 H 17 N₃O₃S₂; C, 52.9; M, 4.7; N, 11.6; S, 17.6 Found: C, 52.9; H, 4.4; N, 11.6; S, 17.5 This compound was identified as 2,3-diamino-3-phenylthio-­ acrylonitrile-p-toluenesulfonate (Compound No. 1) by its I.R. and N.M.R. spectra. Example 2 A solution of diphenyl disulfide (8 g), triethylamine (10 g) and hydrogen cyanide (18 g) in xylene (60 ml) was stirred for 50 minutes at room temperature. The tar left after evaporation of the solvent under reduced pressure was filterd, and a solution of p-toluenesulfonic acid (20 g) in acetonitrile (50 ml) was added to the filtrate. A light yellow precipitate formed was collected by filtration, thoroughly washed successively with acetonitrile and n-hexane, dried in vacuo, and recrystallized from acetonitrile to give light-yellow crystals (5.7 g): m.p. 148-149°C (dec.) The infrared spectrum of this compound was identical with that of 2,3-diamino-3-phenylthio-acrylonitrile-p-toluenesulfonate obtained in example 1. Example 3 To a solution of triethylamine (2 g) and diphenyl disulfide (2 g) in acetonitrile (30 ml) was added 2-aminomalononitrile-p-­ toluenesulfonate (1 g) with stirring for 10 minutes at room temperature. After removal of a half volume of the solvent, p-­ toluenesulfonic acid (2 g) was added to the residue. Work-up in an analogous manner as described in example 1 gave white crystals: m.p. 118-149°C (dec.) The infrared spectrum of this compound was identical with that of 2,3-diamino-3-phenylthio-acrylonitrile-p-toluenesulfonate obtained in example 1. Example 4 A suspension of 2,3-diamino-3-phenylthio-acrylonitrile-p-­ toluenesulfonate (10 g) obtained in example 1 in ethyl acetate (100 ml) was treated with saturated sodium carbonate solution (80 ml) at room temperature. The organic layer was separated, washed with brine and dried with magnesium sulfate. Removal of the solvent under reduced pressure left yellow crystals which were recrystallized from chloroform-n-hexane as light yellow needles: m.p. 86.5-87.5°C (dec.) This compound was identified as 2,3-diamino-3-phenylthio-­ acrylonitrile (Compound No. 3) by its I.R., N.M.R., and MASS and spectra. Example 5 To a chilled solution of dimethyl disulfide (18.8 g), triethylamine (40%) in benzene (250 ml) was added hydrogen cyanide (48 ml) and stirred for 1.5 hours at room temperature. The reaction mixture was poured into an ice-cold 10% sodium hydroxide solution, extracted with ethyl acetate (100 ml). The extract was washed with brine, dried with magnesium sulfate. A solution of p-toluenesulfonic acid (38 g) in acetonitrile (100 ml) was added to this extract to afford a precipitate solid which was collected by filtration, thoroughly washed successively with acetonitrile and n-hexane, and dried in vacuo. 5.2 g of 2,3-diamino-3-methylthio-acrylonitrile-p-­ toluenesulfonate (Compound No. 21) was obtained as light-brown powder: m.p. 181-183°C (dec.) Example 6 To a stirred suspension of thiophenol (10.5 g), 2-­ aminomalononitrile-p-toluenesulfonate (20 g) in acetonitrile (300 ml) was added triethylamine (20 g) at room temperature. After stirring for 1 hour, the solvent was evaporated under reduced pressure to give the residue to which acetonitrile (200 ml) was added followed by adding p-toluenesulfonic acid (20 g). A precipitate solid formed was collected by filtration and thoroughly washed successively with acetonitrile and n-­ hexane to give 7 g of white crystals. Infrared spectrum of this compound was identical with that of 2, 3-diamino-3-phenylthio-­ acrylonitrile-p-toluenesulfonate prepared in example 1. Example 7 To a suspension of ethyl 2-mercaptopropionate (0.4 g) and 2-­ aminomalononitrile-p-toluenesulfonate (0.76 g) was added dropwise triethylamine (0.6 g) at room temperature and stirred for 5 hours. The mixture was evaporated under reduced pressure. Ethyl acetate was added to the residue, washed with water, dried with magnesium sulfate and evaporated again. A solution of p-toluenesulfonic acid (0.6 g) in acetonitrile (20 ml) was added to the residue and allowed to stand overnight in the refrigerator. The precipitate solid was collected by filtration, washed thoroughly with acetonitrile and dried in vacuo. 0.46 g of 2,3-diamino-3-(1-ethoxycarbonylethylthio)acrylo­ nitrile-p-toluenesulfonate (Compound No. 33) was obtained as white powder: m.p. 197-199°C (dec.) Example 8 To a suspension of S-phenyl thioacetate (0.76 g) and 2-­ aminomalononitrile-p-toluenesulfonate (1.26 g) in acetonitrile (10 ml) was added dropwise triethylamine (1 g) at room temperature and stirring was continued for 30 minutes. After evaporation of the solvent under reduced pressure, a solution of p-toluenesulfonic acid (1 g) in acetonitrile (10 ml) was added to the residue to give a crude compound No. 1 which was purified by thoroughly washing acetonitrile and recrystallization from acetonitrile. Example 9 A solution of 2,3-diamino-3-phenylthio-acrylonitrile (1.9 g), benzyl mercaptan (3.7 g) and triethylamine (3 g) in acetonitrile (30 ml) was heated under reflux overnight. After evaporation of the solvent under reduced pressure, a solution of p-­ toluenesulfonic acid (1.7 g) in acetonitrile (30 ml) was added to the residue. The precipitate solid formed was collected by filtration and thoroughly washed successively with acetonitrile and benzene to give 2.2 g of 2,3-diamino-3-benzylthio-­ acrylonitrile-p-toluenesulfonate (Compound No. 26) as light brown powder: m.p. 173-174°C (dec.) Inclusive the above, each compound with the scope of the present invention which can be prepared in analogous method is tabulated in Table 1. Industrial Applicability: The diaminoacrylonitrile derivatives of the present invention can be isolated as stable compounds because the introduction of RS-group into 3 position of 2,3-diaminoacrylonitrile contributes to their stability. As the reference example below shows, said derivatives are so highly reactive that they are useful as materials for preparing a wide variety of organic compounds. Further, as examples above show, said derivatives can be directly synthesized from hydrogen cyanide under mild reaction conditions, hence their manufacture at a low cost is possible. 2-Aminomalononitrile is noted as a trimer of hydrogen cyanide but its high cost and lack of stability have put it out of industrial use. In place of this, the invention offers low-­ cost, stable 2,3-diaminoacrylonitrile derivatives and their manufacturing method, and accordingly its industrial significance is very great. Reference example 1 White crystals obtained in example 1 were, dissolved in a filtrate resulted from the filtration of the crude crystals obtained in example 1. To this solution was added a small amount of triethylamine and then hydrogen cyanide followed by stirring for 10 minutes. Diaminomaleonitrile, a tetramer of hydrogen cyanide, was produced quantitatively.

Claims: 1. A 2,3-diaminoacrylonitrile derivative having the formula (wherein R represents a C 1-24 alkyl group which may be substituted by (unsubstituted or substituted phenyl groups, halogen atoms, C 1-6 alkoxycarbonyl groups, carboxy groups, C 1-6 alkoxycarbonyl C 1-6 alkylthio groups, hydroxy groups, mercapto groups or heterocyclic groups containing oxygen atoms) a C 2-12 alkenyl group, a cycloalkyl group, a C 6-14 aryl group which may be substituted by (halogen atoms, C 1-6 alkyl groups, cycloalkyl groups, nitro-groups, unsubstituted or substituted phenyl or phenoxy groups) or heterocyclic groups containing oxygen atoms or sulfur atoms). 2. A process for the production of a 2,3-diaminoacrylonitrile or salts thereof having the formula which comprises reacting hydrogen cyanide with a compound having the formula RSSR (wherein R represents an alkyl group which may be substituted by (unsubstituted or substituted phenyl groups, halogen atoms, C 1-6 alkoxycarbonyl groups, carboxy groups, C 1-6 alkoxycarbonyl C 1-6 alkylthio groups, hydroxy groups, mercapto groups, cycloalkyl groups or heterocyclic groups containing oxygen atoms), an alkenyl group, a cycloalkyl group, an aryl group which may be substitued by (halogen atoms, C 1-6 alkyl groups, cycloalkyl groups, nitro-groups unsubstituted or substituted phenyl or phenoxy groups) or heterocyclic groups containing oxygen atoms or sulfur atoms). 3. A process for the production of a 2,3-diaminoacrylonitrile derivative or salts thereof having the formula which comprises reacting 2-aminomalononitrile with a compound having the formula (wherein R represents an alkyl group which may be substituted by (unsubstituted or substituted phenyl groups, halogen atoms, C 1-6 alkoxycarbonyl groups, carboxy groups, C 1-6 alkoxycarbonyl C 1-6 alkylthio groups, hydroxy groups, mercapto groups, cycloalkyl groups or heterocyclic groups containing oxygen atoms), an alkenyl group, a cycloalkyl group, an aryl group which may be substituted by (halogen atoms, C 1-6 alkyl groups, cycloalkyl groups, nitro groups, unsubstituted or substituted phenyl or phenoxy groups) or heterocyclic groups containing oxygen atoms or sulfur atoms).

Inventors: HAMAMOTO, ISAMI, MIKUMA, KATSUNORI, UMEDA, NOBUHIRO, YAGIHARA, TOMIO
Applicants: NIPPON SODA CO., LTD.
Application year: 1987
Main classification: C07C323
IPC codes: C07C67, C07D307, C07C313, C07D521, C07D333, C07C323, C07C319