M. Yu. Belikov

Synthesis of photochromic 5,6-diaryl-2-chloropyridine-3,4-dicarbonitriles from 3,4-diaryl-4-oxobutane-1,1,2,2-tetracarbonitriles

We now propose a new synthetic approach to photochromic diarylethenes, which is based on the reaction of tetracyanoethylene with ketones as key intermediate step. Tetracyanoethylation of ketones has been well documented; however, there are almost no published data on reactions of aryl arylmethyl ketones with tetracyanoethylene. Adducts of tetracyanoethylene with ketones of the general formula R(CO)CH2R′ were used as starting compounds to obtain heterocycles containing an RC=CR′ fragment [4–10]. Analogous reactions with aryl arylmethyl ketones Ar(CO)CH2Ar could give rise to various 1,2-diarylethenes as new potential photochromes. We were the first to react tetracyanoethylene with 1,2-diarylethanones Ia and Ib in the presence of a catalytic amount of hydrochloric acid. As a result, we isolated 3,4-diaryl-4-oxobutane-1,1,2,2-tetracarbonitriles IIa and IIb. The substrates were deoxybenzoin (Ia), the parent compound of the 1,2-diarylethanone series, and 1,2-bis(2,5-dimethylthiophen-3-yl)ethanone (Ib). The latter was selected taking into account that diarylethenes containing thienyl substituents are most promising from the viewpoint of the design of practically useful photochromic devices [1]. Ketone Ib was synthesized in a number of steps starting from hexane2,5-dione [11].

Domino-synthesis and fluorescence properties of 4-cyano-2-oxo-1,2-dihydropyridine-3-carboxamides and 2-oxo-1,2-dihydropyridine-3,4-dicarbonitriles

Non-catalytic conversion of 4-oxoalkane-1,1,2,2-tetracarbonitriles in the presence of water leads to the formation of a mixture of fluorescent 4-cyano-2-oxo-1,2-dihydropyridine-3-carboxamides and 2-oxo-1,2-dihydropyridine-3,4-dicarbonitriles in equal proportions. This transformation was explained, spectral-luminescence properties were investigated, and fluorescence quantum yield was measured.

Spiro heterocyclization of 4-aryl-4-oxobutane-1,1,2,2-tetracarbonitriles to 3H-pyrrole derivatives, 2-oxa-7-azaspiro[4.4]nona-3,6,8-trienes

Abstract4-Aryl-3-methyl-4-oxobutane-1,1,2,2-tetracarbonitriles reacted with morpholine to give 8-amino-3-aryl-1-imino-4-methyl-6-(morpholin-4-yl)-2-oxa-7-azaspiro[4.4]nona-3,6,8-triene-9-carbonitriles.

Synthesis and solid-state fluorescence of aryl substituted 2-halogenocinchomeronic dinitriles

Based on the reaction of available adducts of tetracyanoethylene (TCNE) and aromatic ketones (4-aryl-4-oxoalkane-1,1,2,2-tetracarbonitriles) with hydrogen chloride, several aryl substituted 2-halogencinchomeronic dinitriles were synthesized. We found that aryl substituted derivatives, in contrast to alkyl substituted ones, possess an intensive solid state fluorescence. The relationship between the chemical structures and photophysical properties of these compounds was investigated.

Reaction of tetracyanoethylated cyclohexanones with water in acidic medium

It was reported earlier that 4-oxoalkane-1,1,2,2tetracarbonitriles depending on different factors react with hydrohalic acids to form 2-halopyridine-3,4dicarbonitriles [1–3], 2-halo-6-hydroxy-5,6-dihydroxypyridine-3,4,4(1Н)-tricarbonitriles [4], pyrrolo[3,4-c] pyrrole-1,3,4,6(2H,3аH,5H,6аH)-tetraones [1], 3-halo6-oxo-2,7-diazabicyclo[3.2.1]oct-3-ene-4,5-dicarbonitriles [5]. At the same time the influence of the structure of 4-oxoalkane-1,1,2,2-tetracarbonitriles on the reaction with aqueous sulfuric acid was not studied. Only reaction of 50% sulfuric acid with 3-methyl-4oxopentane-1,1,2,2-tetracarbonitrile to afford 5,6-dimethyl-2-oxo-1,2-dihydropyridine-3,4-dicarbonitrile in 10% yield has been reported [3].

Hydrolysis and acylation of imino group in E/Z-isomers of 3,4-dialkyl-8-amino-1-imino-6-morpholin-4-yl-2-oxa-7-azaspiro[4.4]nona-3,6,8-triene-9-carbonitriles

Acid-catalyzed hydrolysis of 3,4-dialkyl-substituted 8-amino-1-imino-6-morpholin-4-yl-2-oxa-7-azaspiro[4.4]nona-3,6,8-triene-9-carbonitriles under mild conditions led to the formation of 8-amino-6-morpholin-4-yl-1-oxo-2-oxa-7-azaspiro[4.4]nona-3,6,8-triene-9-carbonitriles, and their acylation afforded N-(8-amino-9-cyano-6-morpholin-4-yl-2-oxa-7-azaspiro-[4.4]nona-3,6,8-trien-1-ylidene)acetamides. The NMR spectra of compounds synthesized in contrast to the spectra of initial N-unsubstituted imins contained no doubled proton and carbon signals.

Synthesis of diethylammonium 3,4-dicyano-5,6,7,8-tetrahydroquinolin-2-olates

4-Oxoalkane-1,1,2,2-tetracarbonitriles are products of addition of tetracyanoethylene to ketones. Their molecules possess several electrophilic centers capable of reacting with nucleophiles. However, studies on reactions of these compounds with nitrogen-centered nucleophiles are very few in number. It was reported that reactions of 4-oxoalkane-1,1,2,2-tetracarbonitriles with aqueous ammonia lead to formation of isonicotinic acid derivatives [1] and 2,7-diazabicyclo[3.2.1]oct-3-enes [2].

Synthesis of 5-amino-3H-pyrrole-3,4-dicarbonitriles from 4-aryl-4-oxobutane-1,1,2,2-tetracarbonitriles

It is known that 4-oxoalkane-1,1,2,2-tetracarbonitriles react with nitrogen-centered nucleophiles, such as ammonia and amines, to give 3-amino-7-oxo-4,6-diazabicyclo[3.2.1]oct-2-ene-1,2-dicarbonitriles [1], 3-amidinio-2-aminopyridine-4-carboxylates [2], diethylammonium 3,4-dicyano-5,6,7,8-tetrahydroquinolin-2-olates [3], and ammonium 4-aryl-4-oxo-1,1,2-tricyanobut-2-en-1-ides [4]. However, these results do not allow us to draw a definite conclusion on the direction of attack by N-nucleophiles on the reaction centers in polyelectrophilic 4-oxoalkane-1,1,2,2-tetracarbonitriles.

Synthesis of a new organic anion by reaction of 4-aryl(hetaryl)-4-oxobutane-1,1,2,2-tetracarbonitriles with ammonia

4-Oxoalkane-1,1,2,2-tetracarbonitriles are known to react with concentrated aqueous ammonia to produce compounds of two types. Adducts of tetracyanoethylene and cyclic ketones (such as cyclopentanone and cyclohexanone) give rise to 2,7-diazabicyclic compounds [1], whereas from aliphatic tetracyanoethylated ketones isonicotinic acid derivatives are formed [2]. There are no published data on reactions of aqueous ammonia with tetracyanoalkanones derived from methyl aryl(hetaryl) ketones. When such reactions were carried out under the conditions reported in [1, 2], strong tarring occurred, and no individual products were isolated. By varying the conditions of this reaction we succeeded in obtaining ammonium 4-aryl1,1,2,2-tetracyano-4-oxobutan-1-ides IIa–IIc by mixing ketones Ia–Ic with a freshly prepared solution of ammonia in ethyl acetate at reduced temperature. Structures analogous to IIa–IIc but having singly charged metal cations were reported in [3, 4]. Compounds IIa–IIc turned out to be unstable in the solid state: on exposure to air they lost hydrogen cyanide with formation of ammonium 4-aryl-1,1,2-tricyano-4oxobut-2-en-1-ides IIIa–IIIc that are derivatives of a new organic anion. Intermediate formation of ammonium salts IIa–IIc is confirmed by their transformation into initial ketones Ia–Ic by the action of dilute hydrochloric acid immediately after isolation. Some structural similarity of salts IIIa–IIIc to betaines described in [5] may be noted. The latter were synthesized from tetracyanoethylene and pyridinium ylides. The structure of compounds IIIa–IIIc was confirmed by their IR, H NMR, and mass spectra and elemental analyses. The synthesis of salts III is an example of new reaction pathway of 4-oxoalkane1,1,2,2-tetracarbonitriles with ammonia. Ammonium 1,1,2-tricyano-4-(4-methoxyphenyl)4-oxobut-2-en-1-ide (IIIa). 4-(4-Methoxyphenyl)-4oxobutane-1,1,2,2-tetracarbonitrile (Ia), 0.139 g (0.5 mmol), was added to 2 ml of a freshly prepared solution of ammonia in ethyl acetate, cooled to –10°C, and the mixture was vigorously stirred until it became homogeneous. After several minutes, a solid separated and was filtered off, washed with cold ethyl acetate, and kept for 5–7 days on exposure to air. Yield 0.115 g (86%), mp 84–85°C. IR spectrum, ν, cm: 2230, 2199 (C≡N); 1667 (C=O). H NMR spectrum, δ, ppm: 3.81 s (3H, OCH3), 6.51 s (1H, CH), 7.01 d (2H, Harom), 7.07 br.s (4H, NH4), 7.79 d (2H, Harom). Mass spectrum: m/z 251 (Irel 49%) [M – NH3]. Found, %: C 62.51; H 4.77; N 20.95. C14H12N4O2. Calculated, %: C 62.68; H 4.51; N 20.88. Compounds IIIb and IIIc were synthesized in a similar way. Ammonium 1,1,2-tricyano-4-oxo-4-(2-thienyl)but-2-en-1-ide (IIIb). Yield 0.096 g (79%), mp 85– 87°C. IR spectrum, ν, cm: 2221, 2196 (C≡N); 1672 (C=O). H NMR spectrum, δ, ppm: 6.41 s (1H, CH), 7.16 d.d (1H, Harom), 7.19 br.s (4H, NH4), 7.65 d.d (1H, R = 4-MeOC6H4 (a), 2-thienyl (b), 3,4-(MeO)2C6H3 (c). ISSN 1070-4280, Russian Journal of Organic Chemistry, 2010, Vol. 46, No. 4, pp. 597–598.

Synthesis, solution and solid-state fluorescence of 2-diethylaminocinchomeronic dinitrile derivatives

A facile approach to the synthesis of novel 2-diethylaminocinchomeronic dinitriles, which are found to be fluorescent both in the solution and in a solid states, was developed. Absorption, fluorescence and solvatochromic properties as well as a crystal structure of the synthesized compounds were investigated. It was found that the 2-diethylaminocinchomeronic dinitrile derivatives with methoxy groups in the aryl moiety possess the most intensive emission in nonpolar solvents with fluorescence quantum yields up to 0.59.