2.5- diamino-3,4-dicyano

Addition reactions with tetracyanoethane have provided access to 2,5-diamino-3,4-dicyano-thiophene and -selenophene (58JA2775,81ZOR1958). Base catalyzed rearrangement gives the isomeric pyrrolethiol (Scheme 53). 

Selenophene, 2,5-diamino-3,4-dicyano-synthesis, 4, 119, 964 Selenophene, 2,4-diaryl-synthesis, 4, 967 UV spectra, 4, 941 Selenophene, 2,5-diaryl-synthesis, 4, 967, 969 UV spectra, 4, 941 Selenophene, 2,5-dichloro-metallation, 4, 949 Selenophene, dihydro-3-methylene-synthesis, 4, 963 Selenophene, 2,5-dimethoxy-lithiation, 4, 949 Selenophene, 2,4-dimethyl-... 

Thiophene, 2,4-diamino-3,5-dicyano-synthesis, 4, 889, 924 Thiophene, 2,5-diamino-3,4-dicyano-synthesis, 4, 119, 888, 889 Thiophene, 2,5-diaroyl-... 

Malononitrile (133) undergoes Pd(0)-catalyzed dimerization to give 134[125,126]. The trimerization of malononitrile in boiling benzene catalyzed by potassium tetrakis(pentalluorophenyl)palladate gives 4.6-diamino-3,5-dicyano-2-cyanomethylpyridine (135)[127]. 

Substituted 2,6-Diamino-3,5-dicyano-4H-thiopyrans (21) Prepared According to Scheme 1... 

When R in the formimidate is —CH2CF3, 4,5-diamino-2,6-dicyano-pyrimidine forms. This occurs because —OCH2CF3 is a better leaving group than cyanide and is eliminated in the first step rather than cyanide. Cyanoformimidates are available from reaction of alcohols with cyanogen (75USP3883532). 

Diamino-3,4-dicyanothiophene is thus converted by NaOH to 2-amino-3,4-dicyano-5-mercaptopyrrole (Scheme 132) (58JA2822). Here, prior to the recyclization of the intermediate (396), a rotation around the 4,5-bond has occurred. With other substrates such as (397), recyclization results in a thiophene, different from the precursor. Here the 3-substituent is involved in the cyclization and so a rotation around the 3,4-bond is mandatory. One can therefore postulate an intermediate of the type (398) in such reactions ring closure of this will lead to a thiophene-3-carbonitrile which could be either (399) or (400). Some examples are shown in Scheme 133 (75JPR861, 77JCR(S)294). 

Pyridine, 3-amino, 30, 3 5-ETHYL-2-METHYL, 30, 41 4-Pyrimidol, 2,6-diamino-, 32, 45 Pyrogallol-1,3-dimethyl ether, 31, 92 Pyrolysis, of, V-a.zo-bis- -cyclohexane-nitrile to l,l -dicyano-l,l -bicyclo-hexyl, 32, 48... 

As part of a study of the pyrolysis and photolysis of some 4//-thiopyrans, mass spectrometry was used to evaluate fragmentation pathways. The fragmentation pattern of 2,6-diamino-3,5-dicyano-4//-thiopyran is representative of the range of compounds evaluated which included some 4-aryl analogues (Scheme 8) <1998RRC163>. 

Cyclization also occurs extensively with glutaronitriles. In hydrogenation of 1,3-dicyano-2-propanol with Raney Ni, the formation of 4-hydroxypiperidine predominated over the formation of l,5-diamino-3-propanol even in the presence of liquid ammonia.114 Hydrogenation in the absence of ammonia further increased the yield of the piperidine (eq. 7.62). Adiponitrile was transformed to azacycloheptane in high selectivity in the hydrogenation over y-Al203-supported Ni catalysts in a continuous process at 170°C and 0.1 MPa H2 in the absence of ammonia.115... 

The green synthesis of 6-aryl-2,4-diamino-l,3,5-triazines (xviii) from corresponding aryl-nitriles and dicyano diamide using computer controlled microwave irradiation in conjugation with a green solvent [bmim] [PFg] has also been achieved [30]. 

Bredereck and Schmotzer (1044), from diaminomaleonitrile (DAMN hydrogen cyanide tetramer) and oxalyl chloride, prepared 2,3-dicyano-5,6-dihydroxy-pyrazine but Stetten and Fox (1049) could not prepare 23-diamino-5-hydroxy-pyrazine from glycine amide and oxamide. Section 11.3 lists preparations from a, -diamino or a, -diimino compounds and reagents other than a,0-dicarbonyl compounds (384) with additional data (1050) and oxidation of 23-dichloro-quinoxaline with hot aqueous potassium permanganate gave 23-dicarboxy-5,6-dihydroxypyrazine (1051). 

Tetracyanopyrazine has been reported to react with liquid ammonia in tetra-hydrofuran to give 2,6-diamino-3,5-dicyanopyrazine (1180, 1182), and with dimethylamine in tetrahydrofuran at 0° to give 2,3,5-tricyano-6-dimethylamino-pyrazine (97.7%) (158), and this on treatment with ammonia in tetrahydrofuran gave 2-amino-3,5-dicyano-6-dimethylaminopyrazine (89%) (158). 

The following nitriles have been used to prepare carboxypyrazines 2-cyano-3-phenyl [NaOH/ethylene glycol/reflux (1274) or heated with H2S04/NaN02 (1024)] 3-cyano-2,5-dimethyl (NaOH/EtOH/reflux) (1015) 3-cyano-2,5-diphenyl (NaOH) (286) 2,3-dicyano [NaOH/EtOH (354) aq. KOH/EtOH (353) NajOj (357)] 2,6-dicyano (5% NaOH/10072h)(865) 23-dicyano-5,6-dimethyl(Na202) (357) 2-cyano-6-ethylthio(propylthio or phenylthio) (NaOH/EtOH/reflux) (992) 2hydrochloric acid to 2-(3 -carboxy-3 -phenylpropyl)pyrazine (731). 

The dipole moment of 2-chloro-3-cyanopyrazine has been determined as 3.44D in dioxane (749). Polymers have been prepared from 2,3-diamino-5,6-dicyano-... 

Tetracyanopyrazine with liquid ammonia in tetrahydrofuran formed 2,6-diamino-3,5-dicyanopyrazine (1180, 1182), and tetracyanopyrazine with piperazine similarly gave 2,6-dicyano-3,5-dipiperazin-l -ylpyrazine (1182). 

The preparation of some 2,3-dihydropyrazines from a, -dicarbonyl compounds with a,0-diamino compounds has been recorded in Section 11.2 (330, 330a, 331, 333, 334, 338-344, 349, 356, 357), with further data given in references 6, 337, 345, and 1547-1549. In addition hexamethyl-2,3-dihydropyrazine (16) has been prepared from 2,3-diamino-2,3-dimethylbutane and butane-2,3-dione (1550). Condensation of oxalyl chloride with diiminosuccinonitrile (10) in ether has been shown to give 2,3-dichloro-2,3-dicyano-5,6-dihydroxy-2,3-dihydropyrazine (17) (383). 

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