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Nitrosubstituted bis(methylONNazoxyfurazanyl)furoxans O. A. Luk´yanov, G. V. Pokhvisneva, and T. V. Ternikova N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation. Email: [email protected] Reaction of bis(aminofurazanyl)furoxan with 2,2dimethyl5nitro5nitroso1,3dioxane in the presence of dibromoisocyanurate and a series of subsequent transformations give rise to the following bis(mononitroalkyl and polynitromethylONNazoxyfurazanyl)furoxans: bis (nitromethylONNazoxyfurazanyl)furoxan, bis(dinitromethylONNazoxyfurazanyl)furoxan, bis(trinitromethylONNazoxyfurazanyl)furoxan, and a number of their derivatives, including bis(fluorodinitrometylONNazoxyfurazanyl)furoxan. Key words: bis(nitroalkylONNazoxyfurazanyl)furoxans, bis(halonitromethylONN azoxyfurazanyl)furoxans, bis(nitromethylONNazoxyfurazanyl)furoxan, bis(dinitromethyl ONNazoxyfurazanyl)furoxan, bis(trinitromethylONNazoxyfurazanyl)furoxan, bis(fluoro dinitromethylONNazoxyfurazanyl)furoxan, nitration, bromination, debromination, deoxy methylation.

This work is a continuation of our longterm research on the synthesis of high energy compounds of a poly nitroalkylONNazoxyfurazan series. Herein, we stud ied bis(polynitromethylONNazoxyfurazanyl)furoxans. Compounds of this type have not been previously de scribed. Taking into account their structure, one can sug gest that bis(polynitromethylONNazoxyfurazanyl)fur oxans will be promising high energy substances. These compounds can be accessed following the approach ela borated for the synthesis of polynitromethylONNfurazans and via a sequence of transformations of aminofurazans.1—3 In this work, bis(aminofurazanyl)furoxan (1) was used as the starting material. The implemented transformations are shown on Schemes 1 and 2, the spectral data for the synthesized compounds are summarized in Table 1. It is found that diamine 1 smoothly reacts with nitroso compound 2 in the presence of dibromoisocyanurate (DBI) to give the target product 3 in nearly quantitative yield (see Scheme 1). Compound 3 is a crystalline substance melting at 85—87 C. The structure of compound 3 was established by mass spectrometry, IR and NMR 1H, 13C, and 14N spectroscopy and confirmed by a series of subse quent transformations. Similarly to the previously synthe sized compounds bearing the same structural moieties,1—3 treatment of compound 3 with AcCl—MeOH results in the ring opening of both the dioxane cycles to give com pound 4 in nearly quantitative yield. Compound 4 is a heavy oil that does not crystallize on standing. It should be noted that this reaction proceeds noticeably slower than in the case of the earlier described compounds with simi lar structure but bearing the only one furazan cycle and

completed at least within 24 h analogously to the reaction involving compounds bearing two furazan cycles.3 Accord ing to 1H NMR data, tetraol 4 was isolated pure and, therefore, was used on the next step without further pur ification. Next, tetraol 4 was successively treated with aqueous KOH and bromine to give tetrabromide 5 in 64% yield. Tetrabromide 5 is a crystalline compound with melting point of 110—113 C. The structure of compound 5 was evaluated based on elemental analysis data and 13C and 14N NMR spectroscopy. Tetrabromide 5 was further reduced with thiourea in acetic acid. The structures of the products and their yields strongly depend on the reaction conditions, mainly, on the reagent and solvent ratios. The isolated target inter mediate 6 very often contained impurity of the byprod uct, which is apparently a partially reduced product 6´ (1H NMR data). In some cases, (for instance, upon carry ing out the reactions in the media with high water con tent) compound 6´ was the only reaction product. Further reduction of compound 6´ afforded product 6. Never theless, we succeeded in finding conditions to access com pletely reduced product 6 in one step in the yield of 67%. Product 6 is a crystalline compound melting at 67—70 C with decomposition. The structure of compound 6 was established based on spectral data confirming the pres ence of the protons and nitro group, mass spectrometry, and subsequent chemical transformations (see Scheme 2). Thus, it was found that compound 6 readily undergoes nitration under conditions used previously for the nitra tion of a series of nitromethyldiazene oxides (with a mix

Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 0137—0141, January, 2015. 10665285/15/64010137 © 2015 Springer Science+Business Media, Inc.

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Scheme 1

Reagents: i. DBI, CH2Cl2; ii. AcCl, MeOH; iii. 1) KOH, H2O, Et2O, 2) Br2; iv. H2NC(S)NH2, AcOH, H2O.

Scheme 2

B = K (8), NH4 (9)

Reagents and conditions: i. HNO3, N2O4, 45—48 C, 13 h; ii. KOH, MeCN (for 8) or NH3, CH2Cl2 (for 9); iii. XeF2; iv. HNO3, H2SO4, SO3.

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Table 1. Spectral data for (nitroalkylONNazoxyfurazanyl)furoxanes 3, 5—7, 10, and 11 Com pound

IR,

NMR, , J/Hz

Solvent

/cm–1

13C

1H

3

1636, 1578, 1381 (NO2); 1509, 1201 (N2O)

CDCl3

1.60 (s, 12 Н, 4 CH3); 4.75 (s, 8 H, 4 CH2)

5

1607, 1314 (NO2); 1519, 1259 (N2O)

CDCl3

—

6

1635; 1586, 1366 (NO2); 1520, 1212 (N2O)

CDCl3 Acetoned6

6.38, 6.39 (both s, 2 СН2) 7.03, 7.11 (both s, 2 СН2)

7

1639; 1611, 1311 (NO2); 1530, 1272 (N2O)

Acetoned6

9.36, 9.51 (both s, 2 СН)

10

1620, 1323 (NO2); 1530, 1272 (N2O)

CDCl3

— —

11

1641, 1614, 1321 (NO2); 1529, 1270 (N2O)

CDCl3

— —

ture of concentrated nitric acid and nitrogen tetroxide)4. Prolonged heating of compound 6 (~13 h, 45—48 C) furnished the target intermediate 7 in 68% yield. Crystall ine compound 7 melts with decomposition at 124—126 C. The structure of compound 7 was evaluated using elemen tal analysis data, high resolution mass spectrometry, and 1H, 13C, and 14N NMR spectroscopy. We found that compound 7 readily reacts with bases to give the corresponding salts. Potassium salt 8 melts at 118—120 C, ammonium salt 9, at 143—146 C with de composition. Salts 8 and 9 were obtained in the yields of 65—70%. It is worthy of note that potassium salt 8 can be isolated from the reaction mixture by preparative TLC. The structure of salt 8 was confirmed by its quantitative transformation into the starting compound 7 in the acidic media. Potassium salt 8 is moderately soluble in MeCN. Treatment of the MeCN solution of salt 8 with xenon difluoride at 50 C results in furoxan 10. Compound 10 is a crystalline solid with melting point of 65—68 C, it starts to decompose at 190 C with the intensive stage of decom position at 225 C. It was found that prolonged treatment (48 h) of compound 7 with the preliminary prepared mix ture of trifluoroacetic anhydride—HNO3 at 20 C (see

21.9, 22.7, 23.0, 23.8 (CH3); 62.3, 62.4 (CH2); 101.1 (C(CH3)2); 108.1, 108.4 CNO2); 105.4 (C(4)); 136.7 (C(3)); 139.8 (C(5)); 143.6 (C(2)); 153.0 (C(6)); 153.3 (C(1)) 116.5 (C(NO2)Br2); 102.0 (C(4)); 137.4 (C(3)); 140.3 (C(5)); 143.2 (C(2)); 153.5 (C(1), C(6)) 0000000000—

115.1 (CН(NO2)2; 104.6 (C(4)); 139.4 (C(3)); 142.0 (C(5)); 144.6 (C(2)); 153.5 (C(6)); 154.3 (C(1)) 112.0, 115.5 (CF(NO2)2, JC,F = 323.7); 103.1 (C(4)); 137.5 (C(3)); 142.0, 144.6, 140.3, 142.3, 151.4, 152.0 (furazan) 118.4 (C(NO2)3); 102.8 (C4)); 137.8 (C(3)); 140.6 (C(5)); 142.4 (C(2)); 151.6 (C(6)); 152.4 (C(1))

14N

–49.07 (NO); –13.84 (NO2)

–48.40 (NO); –24.30 (NO2) 00000—

–65.12 (NO); –33.99 (NO2)

–72.00 (br.s, NO); –40.99, –40.54 (NO2)

–49.11 (NO2)

Ref. 5) leads to compound 11 in 57% yield. Compound 11 can also be obtained by the twostep nitration of com pound 6 without isolation of intermediate 7: on the first step nitration is carried out with 95% nitric acid in the presence of nitrogen tetroxide and on the next step oleum is added. Thus obtained oxidizer 11 is a crystalline com pound with melting point of 68—70 C, temperature of the decomposition onset of 110 C, and temperature of the intensive decomposition of 137 C. Experimental The reaction course was monitored with precoated TLC plates Silufol UV254. IR spectra were recorded on a UR20 spectrophotometer. NMR spectra were run with a Bruker AM300 instrument. High resolution electrospray mass spectro metry was carried out with a Bruker micrOTOF II instrument. Melting points were determined on a Kofler hotstage appara tus. Diamine 1 was synthesized in three steps by the known procedures.6—8 Dibromoisocyanurate9 and 2,2dimethyl5 nitro5nitroso1,3dioxane (2)10 were synthesized as previous ly described. Bis(2,2dimethyl5nitro1,3dioxan5ylONNazoxyfur azanyl)furoxan (3). To a stirred solution of pseudo nitrol 2 (2.36 g,

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12.4 mmol) in CH2Cl2 (20 mL), DBI (5.4 g, 18.8 mmol) and diamine 1 (1.5 g, 6 mmol) were added. The reaction mixture was stirred at 20 C for 1.5 h and passed through a SiO2 pad (elution with CH2Cl2), and the filtrate was concentrated to dryness. The residue was crystallized by triturating with hexane. Yield 3.24 g (87%). M.p. 85—87 C (hexane). MS (ESI), m/z: 629.4282 [M + H]+, 651.4119 [M + Na]+. C18H20N12O14. Calculated: 629.4324 [M + H]+, 651.4142 [M + Na]+. Bis(1,3dihydroxy2nitropropyl2ONNazoxyfurazanyl) furoxan (4). To a stirred solution of compound 3 (0.45 g, 0.7 mmol) in MeOH (20 mL), AcCl (2 mL) was added dropwise. The reaction mixture was kept at 20 C for 24 h and the volatiles were removed in vacuo. The residue was washed with CHCl3 to give tetraol 4 in the yield of 0.38 g (97%), heavy oil. IR, /cm–1: 3425 (OH), 1513, 1231 (N=NO), 1574, 1340 (NO2). 1H NMR (acetoned6), : 4.50 (s, 4 H, 2 CH2); 4.68 (s, 4 H, 2 CH2); 5.30 (br.s, 4 H, 4 OH). Crude compound 4 was deoxymethylated and brominated to give tetrabromide 5 without further purification. Bis(dibromonitromethylONNazoxyfurazanyl)furoxan (5). To a vigorously stirred solution of crude tetraol 4 (1.5 g, 2.74 mmol) in diethyl ether (95 mL), a solution of KOH (2.2 g, 39 mmol) in water (50 mL) was added at 5—15 C (ice cooling). The reaction mixture turned dark red. After the KOH adding, the stirring was continued for 5 min, the cooling was removed, and bromine was added until bromine color faded. The reaction temperature was graduately raised to 20—25 C and after addi tion of all portion of bromine the reaction pH was 7. The organic layer was separated, dried with MgSO4, and the solvent was removed in vacuo. The residue was passed through a SiO2 pad (elution with CH2Cl2). Removal of the solvent in vacuo afforded tetrabromide 5 in the yield of 1.32 g (64% overall yield for three steps from compound 1), heavy oil. Crystalline sample of compound 5 was obtained by recrystallization from diethyl ether—hexane. M.p. 108—113 C (hexane). Found (%): C, 12.91; Br, 42.91; N, 22.47. C8N12Br4O10. Calculated (%): C, 12.90; Br, 43.01; N, 22.58. Bis(nitromethylONNazoxyfurazanyl)furoxan (6). A. To a solution of tetrabromide 5 (0.68 g, 0.92 mmol) in glacial AcOH (4 mL), a solution of thiourea (0.2 g, 2.63 mmol) in water (4 mL) was added dropwise. The reaction mixture was stirred at 20 C for 20 min and then quenched by fast addition of water (10 mL) to precipitate orange oily residue. Further stirring of the residue for 2 h resulted in its crystallization. The precipitate was collect ed by filtration, washed with water, and dried in air to give com pound 6 in the yield of 0.26 g (67%). M.p. 65—70 C (decomp.). MS (ESI), m/z: 427.1817 [M – H]+. C8H4N12O10. Calculated: 427.1824 [M – H]+. B. To a stirred solution of tetrabromide 5 (0.31 g, 0.42 mmol) in glacial AcOH (2 mL), a solution of thiourea (0.1 g, 1.3 mmol) in water (6 mL) was added, and the yellow oily residue was immediately formed. The reaction mixture was stirred at 20 C for 10 min and the solvent was decanted. To the residue, water (6 mL) was added and stirring was continued for 1 h. Yellow crystals of dibromide 6´ were collected by filtration, washed with water, and dried in air. Yield 0.18 g (73%). 1H NMR (CDCl3), : 7.28 (s, 2 CH). 1H NMR (acetoned6), : 8.82, 8.96 (both s, 2 CH). To a stirred solution of dibromide 6´ (0.175 g, 0.26 mmol) in glacial AcOH (2 mL), a solution of thiourea (0.06 g, 0.78 mmol) in water (1 mL) was added. The reaction mixture was stirred at 20 C for 15 min and carefully diluted with water (3 mL) with stirring. The precipitate was collected by filtration, washed with

Luk´yanov et al.

water, and dried in air to give compound 6 in the yield of 0.05 g (39%). Physicochemical properties of the samples obtained by methods A and B are identical. Bis(dinitromethylONNazoxyfurazanyl)furoxan (7). A mix ture of compound 6 (0.29 g, 0.68 mmol), 95% HNO3 (4 mL), and N2O4 (2 mL) was heated at 45—48 C for 13 h in a sealed flask. The reaction mixture was cooled down, poured onto ice, the precipitate formed was collected by filtration, washed with water, and dried in air to give tetranitro derivative 7 in the yield of 0.24 g (68%). M.p. 124—126 C (decomp.). Found (%): C, 18.49; H, 0.25; N, 37.33. C8H2N14O14. Calculated (%): C, 18.53; H, 0.39; N, 37.84. MS (ESI), m/z: 517.1635 [M + H]+. C8H2N14O14. Calculated: 517.1658 [M + H]+. Dipotassium salt of bis(dinitromethylONNazoxyfurazan yl)furoxan (8). To a solution of tetranitro derivative 7 (0.24 g, 0.46 mmol) in anhydrous MeCN (10 mL), a finely powdered KOH (0.052 g, 0.92 mmol) was added. The resulted suspension was stirred at 20 C for 40 min, filtered, and the solvent was removed to dryness in vacuo. Purification of the residue by pre parative TLC (elution with benzene—acetone, 1 : 2) afforded potassium salt 8 in the yield of 0.19 g (69%), m.p. 115—118 C. Addition of an aqueous HCl solution to a suspension of salt 8 in CH2Cl2 led to compound 7 in quantitative yield. Diammonium salt of bis(dinitromethylONNazoxyfurazanyl) furoxan (9). A solution of tetranitro derivative 7 (0.19 g, 0.37 mmol) in anhydrous CH2Cl2 (6 mL) was stirred for 30 min under gas eous ammonia. The precipitate formed was filtered and washed with diethyl ether to give salt 9 in the yield of 0.13 g (64%), m.p. 143—146 C (decomp.). Found (%): C, 17.30; H, 1.18. C8H8N16O14. Calculated (%): C, 17.39; H, 1.45. 1H NMR (acet oned6), : 7.00 (br.s, 2 NH4). 13C NMR (acetoned6), : 103.81, 137.82 (furoxan); 141.09, 144.22, 154.03, 155.31 (furazan). 14N NMR (acetoned ), : –33.99 (NO ), –362.93 (NH +). IR, 6 2 4 /cm–1: 3433, 3246, 1650, 1597, 1478, 1261, 1150. Bis(fluoronitromethylONNazoxyfurazanyl)furoxan (10). A mixture of salt 8 (0.19 g, 0.32 mmol) and XeF2 (0.215 g, 1.27 mmol) in anhydrous MeCN (15 mL) was stirred at 50 C for 1 h and then kept at 20 C for 16 h. Removal of the solvent in vacuo and purification of the residue by preparative TLC (elu tion with benzene—hexane, 1 : 1) afforded fluorinated compound 10 in the yield of 0.079 g (45%), colorless crystals. M.p. 65—68 C. Found (%): C, 17.52; N, 34.88. C8F2N14O14. Calculated (%): C, 17.32; N, 35.38. 19F NMR (CDCl3), : –88.62; –89.07. Bis(trinitromethylONNazoxyfurazanyl)furoxan (11). A. To a solution of trifluoroacetic anhydride (1.7 mL) in CH2Cl2 (2.4 mL), fuming HNO3 (2 mL) was added at 0—5 C. After 15 min stirring, tetranitro derivative 7 (0.12 g, 0.23 mmol) was added. The reaction mixture was stirred at 20 C for 14 h, poured onto ice, extracted with CH2Cl2 (3×5 mL), washed with water (3×3 mL), and dried with MgSO4. Removal of the solvent and purification of the residue by preparative TLC (elution with benz ene—hexane, 1 : 1) afforded hexanitro compound 11 in the yield of 0.08 g (57%), m.p. 68—70 C. Found (%): C, 15.85; N, 36.42. C8N16O18. Calculated (%): C, 15.80; N, 36.84. B. A mixture of compound 6 (0.089 g, 0.21 mmol), 95% HNO3 (1.5 mL), and N2O4 (0.6 mL) was heated in a sealed flask at 45—48 C for 13 h. After cooling down, 16% oleum (1.5 mL) was added and the mixture was kept at 68—70 C for 14 h. Then, the mixture was poured onto ice, extracted with CH2Cl2 (3×5 mL), washed with water (3×3 mL), and dried with MgSO4. Removal of the solvent in vacuo and purification of the residue

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by preparative TLC (elution with benzene—hexane, 1 : 1) af forded compound 11 in the yield of 0.68 g (54% for 2 steps). Physicochemical properties of the samples obtained by methods A and B are identical.

Authors are grateful to M. I. Struchkova, E. D. Lubuzh, and N. G. Kolotyrkina (N. D. Zelinsky Institute of Organic Chemistry, RAS) for the measuring NMR, IR, and mass spectra and Yu. N. Burtsev and I. B. Barskaya (N. S. Kurnakov Institute of General and Inorganic Chemistry, RAS) for the determination of melting points and decom position points of several compounds. References 1. O. A. Luk´yanov, G. V. Pokhvisneva, T. V. Ternikova, N. I. Shlykova, M. E. Shagaeva, Russ. Chem. Bull. (Int. Ed.), 2011, 60, 1703 [Izv. Akad. Nauk, Ser. Khim., 2011, 1678]. 2. O. A. Luk´yanov, G. V. Pokhvisneva, T. V. Ternikova, N. I. Shlykova, Russ. Chem. Bull. (Int. Ed.), 2012, 61, 360 [Izv. Akad. Nauk, Ser. Khim., 2012, 358].

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3. O. A. Luk´yanov, G. V. Pokhvisneva, T. V. Ternikova, Russ. Chem. Bull. (Int. Ed.), 2012, 61, 1783 [Izv. Akad. Nauk, Ser. Khim., 2012, 1767]. 4. O. A. Luk´yanov, G. V. Pokhvisneva, T. V. Ternikova, Russ. Chem. Bull. (Int. Ed.), 2015, 64, 83 [Izv. Akad. Nauk, Ser. Khim., 2015, 83]. 5. V. V. Parakhin, A. Luk´yanov, Russ. Chem. Bull. (Int. Ed.), 2013, 62, 2007 [Izv. Akad. Nauk, Ser. Khim., 2013, 2007]. 6. T. Ichikawa, T. Kato, T. Takenishi, J. Het. Chem., 1965, 2, 253. 7. US Pat. Appl. 20100015178; http://appft.uspto.gov/netahtml/ PTO/srchnum.html. 8. J. Wang, J. Li, Q. Liang, H. Dong, Propellants Explos. Pyro tech., 2008, 347. 9. W. Gottardi, Monatsh. Chem., 1968, 99, 815. 10. O. A. Luk´yanov, Yu. B. Salamonov, A. B. Bass, Yu. A. Strelenko, Bull. Acad. Sci. USSR, Div. Chem. Sci. (Engl. Transl.), 1991, 40, 93 [Izv. Akad. Nauk, Ser. Khim., 1991, 109]. Received May 7, 2014; in revised form July 3, 2014