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

Abstract

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. © Pleiades Publishing, Ltd., 2010. Original Russian Text © M.Yu. Belikov, O.V. Ershov, A.V. Eremkin, Ya.S. Kayukov, O.E. Nasakin, 2010, published in Zhurnal Organicheskoi Khimii, 2010, Vol. 46, No. 4, pp. 604–605.