a Molecular Electron Density Theory. All of the considered processes were found to be initiated by the attack of the most nucleophilic oxygen atom in the benzonitrile N-oxide on the most electrophilic carbon atom (Cα) in the nitroalkenes. This type of interaction favours the formation of 4-nitro-substituted
Δ2-isoxazolines.
How to cite this paper
Kula, K & Zawadzińska, K. (2021). Local nucleophile-electrophile interactions in [3+2] cycloaddition reactions between benzonitrile N-oxide and selected conjugated nitroalkenes in the light of MEDT computational study.Current Chemistry Letters, 10(1), 9-16.
References
1 Kamimura A. (1992) Recent Development of the Chemistry of 2-isoxazolines. Focused on its regio- and stereoselectivity. Syn. Org. Synth. Jpn., 50 (9), 808-825.
2 Kanemasa S., and Tsuge O. (1990) Recent advances in synthetic applications of nitrile oxide cycloaddition. Heterocycles, 30 (1), 719-736.
3 Sewald N. (2003) Synthetic Routes towards enantiomerically pure β‐amino acids. Angew. Chem. Int. Ed., 42 (47), 5794-5795.
4 Brandi A., Cordero F. M., De Sarlo F., Goti A., and Guarna A. (1993) New synthesis of azaheterocycles by cearrangement of isoxazoline-5-spirocycloalkane compounds. Synlett, 1, 1-8.
5 Harada K., Kaji E., Takahashi K., and Zen S. (1997) Ring Transformation of 2‐isoxazoline 2‐oxides by Lewis Acids. Rev. Heteroat. Chem., 28 (41), 171-195.
6 Vilela G. D., da Rosa R. R., Schneider P. H., Bechtold I. H., Eccher J., and Merlo A. A. (2011) Expeditious preparation of isoxazoles from Δ2-isoxazolines as advanced intermediates for functional materials. Tetrahedron Lett., 52 (49), 6569-6572.
7 Jeddeloh M. R., Holden J. B., Nouri D. H., and Kurth M. J. (2007) A library of 3-aryl-4,5-dihydroisoxazole-5-carboxamides. J. Comb. Chem., 9 (6), 1041-1045.
8 Bouayad N., Rharrabe K., Lamhamdi M., Nourouti N. G., and Sayah F. (2012) Dietary effects of harmine, α,β-carboline alkaloid, on development, energy reserves and α-amylase activity of Plodia interpunctella Hübner (Lepidoptera: Pyralidae). Saudi J. Biol. Sci., 19 (1), 73-80.
9 Quadrelli P., Vazquez Martinez N., Scrocchi R., Corsaro A., and Pistarà V. (2014) Syntheses of isoxazoline-carbocyclic nucleosides and their antiviral evaluation: A Standard Protocol. Sci. World J., 1-12.
10 Znati M., Debbabi M., Romdhane A., Ben Jannet H., and Bouajila J. (2018) Synthesis of new anticancer and anti-inflammatory isoxazolines and aziridines from the natural (-)-deltoin. J. Pharm. Pharmacol., 70 (12), 1700-1712.
11 Saravanan G., Alagarsamy V., and Dineshkumar P. (2013) Synthesis, analgesic, anti-inflammatory and in vitro antimicrobial activities of some novel isoxazole coupled quinazolin-4(3H)-one derivatives. Arch. Pharmacal Res., 1-11.
12 Filal I., Bouajila J., Znati M., Bousejra-El Garah F., and Ben Jannet H. (2014) Synthesis of new isoxazoline derivatives from harmine and evaluation of their anti-Alzheimer, anti-cancer and anti-inflammatory activities. J. Enzyme Inhibit. Med. Chem., 30 (3), 371-376.
13 Mondal P., Jana S., Balaji A., Ramakrishna R., and Kanthal L. K. (2012) Synthesis of some new isoxazoline ierivatives of chalconised indoline-2-one as a potential analgesic, antibacterial and anthelmimtic agents. J. Young Pharm., 4 (1), 38-41.
14 Barceló M., Raviña E., Masaguer C. F., Domínguez E., Areias F. M., Brea J., and Loza M. I. (2007) Synthesis and binding affinity of new pyrazole and isoxazole derivatives as potential atypical antipsychotics. Bioorg. Med. Chem. Lett., 17 (17), 4873-4877.
15 Krupa A., Zwierzyńska E., and Pietrzak B. (2013) Zonisamid – lek nie tylko przeciwpadaczkowy. Aktualn. Neurol., 13 (3), 183-188.
16 Sharifi B., Zade B. G., Zoladl M., Najafi D. S., Ghafarian S., Hamid R., Hashemi M., and Abad N. (2012) Side effects of risperidone. Life Sci. J., 9 (3), 1463-1467.
17 Kaur K., Kumar V., Sharma A. K., and Gupta G. K. (2013) Isoxazoline containing natural products as anticancer agents: A review. Eur. J. Med. Chem., 77, 121-133.
18 Lingaraju G. S., Balaji K. S., Jayarama S., Anil S. M., Kiran K. R., and Sadashiva M. P. (2018) Synthesis of new coumarin tethered isoxazolines as potential anticancer agents. Bioorg. Med. Chem. Lett., 28 (23-24), 3606-3612.
19 Chen F., Yang X.-L, Wu Z.-W., and Han B. (2016) Synthesis of isoxazoline/cyclic nitrone-featured methylenes using unsaturated ketoximes: A dual role of TEMPO. J. Org. Chem., 81 (7), 3042-3050.
20 Minakata S., Okumura S., Nagamachi T., and Takeda Y. (2011) Generation of nitrile oxides from oximes using t-BuOI and their cycloaddition. Org. Lett., 13 (11), 2966-2969.
21 Łapczuk-Krygier A., Kącka-Zych A., and Kula K. (2019) Recent progress in the field of cycloaddition reactions involving conjugated nitroalkenes. Current Chem. Lett., 8 (1), 13-38.
22 Domingo L. R., Ríos-Gutiérrez M., Silvi B., and Pérez P. (2018) The mysticism of pericyclic reactions: A contemporary rationalisation of organic reactivity based on electron density analysis. Eur. J. Org. Chem., 2018 (9), 1107-1120.
23 Jasiński R., Jasińska E., and Dresler E. (2017) A DFT computational study of the molecular mechanism of [3+2] cycloaddition reactions between nitroethene and benzonitrile N-oxides. J. Mol. Model., 23, 13-21.
24 Łapczuk-Krygier A., Ponikiewski Ł., and Jasiński R. (2014) The crystal structure of (1RS,4RS,5RS, 6SR)-5-cyano-5-nitro-6-phenylbicyclo[2.2.1]hept-2-ene. Crystallogr. Rep., 59 (7), 961-963.
25 Ono N. (2001) The nitro group in organic synthesis, 1st Ed, Wiley-VCH, New York.
26 Feuer H. (2001) Nitrile oxides, nitrones, and nitronates in organic synthesis, 2nd Ed, John Wiley & Sons, New Jersey.
27 Jasiński R., Kula K., Kącka A. and Mirosław B. (2017) Unexpected course of reaction between (E)-2-aryl-1-cyano-1-nitroethenes and diazafluorene: why is there no 1,3-dipolar cycloaddition? Monats. Chem., 148 (5), 909-915.
28 Boguszewska-Czubara A., Kula K., Wnorowski A., Biernasiuk A., Popiołek Ł., Miodowski D., Demchuk O. M., and Jasiński R. (2019) Novel functionalized β-nitrostyrenes: Promising candidates for new antibacterial drugs. Saudi Pharm. J., 27 (4), 593-601.
29 Bigotti S., Malpezzi L., Molteni M., Mele A. Panzeri W., and Zanda M. (2009) Functionalized fluoroalkyl heterocycles by 1,3-dipolar cycloadditions with γ-fluoro-α-nitroalkenes. Tetrahedron Lett., 50 (21), 2540-2542.
30 Frisch M. J., Trucks G. W., Schlegel H. B., Scuseria G. E., Robb M. A., Cheeseman J. R., Scalmani G., Barone V., Mennucci B., Petersson G. A., Nakatsuji H., Caricato M., Li X., Hratchian H. P., Izmaylov A. F., Bloino J., Zheng G., Sonnenberg J. L., Hada M., Ehara M., Toyota K., Fukuda R., Hasegawa J., Ishida M., Nakajima T., Honda Y., Kitao O., Nakai H., Vreven T., Montgomery J. A. Jr., Peralta J. E., Ogliaro F., Bearpark M., Heyd J. J., Brothers E., Kudin K. N., Staroverov V. N., Keith T., Kobayashi R., Normand J., Raghavachari K., Rendell A., Burant J. C., Iyengar S. S., Tomasi J., Cossi M., Rega N., Millam J. M., Klene M., Knox J. E., Cross J. B., Bakken V., Adamo C., Jaramillo J., Gomperts R., Stratmann R. E., Yazyev O., Austin A. J., Cammi R., Pomelli C., Ochterski J. W., Martin R. L., Morokuma K., Zakrzewski V. G., Voth G. A., Salvador P., Dannenberg J. J., Dapprich S., Daniels A. D., Farkas O., Foresman J. B., Ortiz J. V., Cioslowski J., and Fox D. J. (2013) Gaussian 16, Revision A.03. Gaussian Inc., Wallingford CT.
31 Parr R. G., and Yang W. (1979) Density-functional theory of atoms and molecules, in: Fukui K., and Pullman B. (Eds) Horizons of Quantum Chemistry. Springer, Netherlands, 5-15.
32 Pérez P., Domingo L. R., Aizman A., and Contreras R. (2007) The electrophilicity index in organic chemistry, in: Toro-Labbé A. (Eds) Theoretical and Computational Chemistry. Elsevier, Oxford, United Kingdom, 139-201.
33 Perez P., Domingo L. R., Aurell M. J., and Contreras R. (2003) Quantitative characterization of the global electrophilicity pattern of some reagents involved in 1,3-dipolar cycloaddition reactions. Tetrahedron, 59 (17), 3117-3125.
34 Pérez P., Domingo L. R., Duque-Noreña M., and Chamorro E. (2009) A condensed-to-atom nucleophilicity index. An application to the director effects on the electrophilic aromatic substitutions. J. Mol. Struct. (THEOCHEM), 895 (1-3), 86-91.
35 Domingo L. R., Perez P., and Saez J. A. (2013) Understanding the local reactivity in polar organic reactions through electrophilic and nucleophilic Parr functions. RSC Adv., 3 (5), 1486-1494.
36 Domingo L. R., and Saez J. A. (2009) Understanding the mechanism of polar Diels-Alder reactions. Org. Biomol. Chem., 7 (17), 3576-3583.
37 Kapłon K., Demchuk O. M., Wieczorek M., and Pietrusiewicz K. M. (2014) Brönsted acid catalyzed direct oxidative arylation of 1,4-naphthoquinone. Current Chem. Lett., 3 (1), 23-36.
38 Parr R. G., Szentpály L., and Liu S. (1999) Electrophilicity Index. J. Am. Chem. Soc., 121 (9), 1922-1924.
39 Domingo L. R., Ríos-Gutiérrez M., and Pérez P. (2016) Applications of the Conceptual Density Functional Theory Indices to Organic Chemistry Reactivity. Molecules, 2016, 21 (6), 748-769.
40 Jasiński R., Żmigrodzka M., Dresler E., and Kula K. (2017) A full regio- and stereoselective synthesis of 4-nitroisoxazolidines via stepwise [3+2] cycloaddition reactions between (Z)-C-(9-anthryl)-N-arylnitrones and (E)-3,3,3-trichloro-1-nitroprop-1-ene: Comprehensive experimental and theoretical study. J. Heterocycl. Chem., 54 (6), 3314-3320.
41 Kula K., Dobosz J., Jasiński J., Kącka-Zych A., Łapczuk-Krygier A., Mirosław B., and Demchuk O. M. (2020) [3+2] Cycloaddition of diaryldiazomethanes with (E)-3,3,3-trichloro-1-nitroprop-1-ene: An experimental, theoretical and structural study. J. Mol. Struct., 1203, 127473.
42 Mloston G., Jasiński R., Kula K., and Heimgartner H. (2020) A DFT study on the Barton–Kellogg reaction – The molecular mechanism of the formation of thiiranes in the reaction between diphenyldiazomethane and diaryl thioketones. Eur. J. Org. Chem., 2020 (2), 176-182.
43 Jasiński R. (2015) A stepwise, zwitterionic mechanism for the 1,3-dipolar cycloaddition between (Z)-C-4-methoxyphenyl-N-phenylnitrone and gem-chloronitroethene catalyzed by 1-butyl-3-methylimidazolium ionic liquid cations. Tetrahedron Lett., 56 (3), 532-535.
44 Cholewka E. (1995) Kinetic of reactions of benzonitrile N-oxides with trans-β-nitrostyrenes and thermolysis if obtained diarylisoxazolines, PhD dissertation, Cracow, Poland.
45 Boyer J. H. (1986) Nitroazoles. The C-Nitro Derivatives of Five-Membered N- and N,O- Heterocycles. VCH Publisher, United States.
2 Kanemasa S., and Tsuge O. (1990) Recent advances in synthetic applications of nitrile oxide cycloaddition. Heterocycles, 30 (1), 719-736.
3 Sewald N. (2003) Synthetic Routes towards enantiomerically pure β‐amino acids. Angew. Chem. Int. Ed., 42 (47), 5794-5795.
4 Brandi A., Cordero F. M., De Sarlo F., Goti A., and Guarna A. (1993) New synthesis of azaheterocycles by cearrangement of isoxazoline-5-spirocycloalkane compounds. Synlett, 1, 1-8.
5 Harada K., Kaji E., Takahashi K., and Zen S. (1997) Ring Transformation of 2‐isoxazoline 2‐oxides by Lewis Acids. Rev. Heteroat. Chem., 28 (41), 171-195.
6 Vilela G. D., da Rosa R. R., Schneider P. H., Bechtold I. H., Eccher J., and Merlo A. A. (2011) Expeditious preparation of isoxazoles from Δ2-isoxazolines as advanced intermediates for functional materials. Tetrahedron Lett., 52 (49), 6569-6572.
7 Jeddeloh M. R., Holden J. B., Nouri D. H., and Kurth M. J. (2007) A library of 3-aryl-4,5-dihydroisoxazole-5-carboxamides. J. Comb. Chem., 9 (6), 1041-1045.
8 Bouayad N., Rharrabe K., Lamhamdi M., Nourouti N. G., and Sayah F. (2012) Dietary effects of harmine, α,β-carboline alkaloid, on development, energy reserves and α-amylase activity of Plodia interpunctella Hübner (Lepidoptera: Pyralidae). Saudi J. Biol. Sci., 19 (1), 73-80.
9 Quadrelli P., Vazquez Martinez N., Scrocchi R., Corsaro A., and Pistarà V. (2014) Syntheses of isoxazoline-carbocyclic nucleosides and their antiviral evaluation: A Standard Protocol. Sci. World J., 1-12.
10 Znati M., Debbabi M., Romdhane A., Ben Jannet H., and Bouajila J. (2018) Synthesis of new anticancer and anti-inflammatory isoxazolines and aziridines from the natural (-)-deltoin. J. Pharm. Pharmacol., 70 (12), 1700-1712.
11 Saravanan G., Alagarsamy V., and Dineshkumar P. (2013) Synthesis, analgesic, anti-inflammatory and in vitro antimicrobial activities of some novel isoxazole coupled quinazolin-4(3H)-one derivatives. Arch. Pharmacal Res., 1-11.
12 Filal I., Bouajila J., Znati M., Bousejra-El Garah F., and Ben Jannet H. (2014) Synthesis of new isoxazoline derivatives from harmine and evaluation of their anti-Alzheimer, anti-cancer and anti-inflammatory activities. J. Enzyme Inhibit. Med. Chem., 30 (3), 371-376.
13 Mondal P., Jana S., Balaji A., Ramakrishna R., and Kanthal L. K. (2012) Synthesis of some new isoxazoline ierivatives of chalconised indoline-2-one as a potential analgesic, antibacterial and anthelmimtic agents. J. Young Pharm., 4 (1), 38-41.
14 Barceló M., Raviña E., Masaguer C. F., Domínguez E., Areias F. M., Brea J., and Loza M. I. (2007) Synthesis and binding affinity of new pyrazole and isoxazole derivatives as potential atypical antipsychotics. Bioorg. Med. Chem. Lett., 17 (17), 4873-4877.
15 Krupa A., Zwierzyńska E., and Pietrzak B. (2013) Zonisamid – lek nie tylko przeciwpadaczkowy. Aktualn. Neurol., 13 (3), 183-188.
16 Sharifi B., Zade B. G., Zoladl M., Najafi D. S., Ghafarian S., Hamid R., Hashemi M., and Abad N. (2012) Side effects of risperidone. Life Sci. J., 9 (3), 1463-1467.
17 Kaur K., Kumar V., Sharma A. K., and Gupta G. K. (2013) Isoxazoline containing natural products as anticancer agents: A review. Eur. J. Med. Chem., 77, 121-133.
18 Lingaraju G. S., Balaji K. S., Jayarama S., Anil S. M., Kiran K. R., and Sadashiva M. P. (2018) Synthesis of new coumarin tethered isoxazolines as potential anticancer agents. Bioorg. Med. Chem. Lett., 28 (23-24), 3606-3612.
19 Chen F., Yang X.-L, Wu Z.-W., and Han B. (2016) Synthesis of isoxazoline/cyclic nitrone-featured methylenes using unsaturated ketoximes: A dual role of TEMPO. J. Org. Chem., 81 (7), 3042-3050.
20 Minakata S., Okumura S., Nagamachi T., and Takeda Y. (2011) Generation of nitrile oxides from oximes using t-BuOI and their cycloaddition. Org. Lett., 13 (11), 2966-2969.
21 Łapczuk-Krygier A., Kącka-Zych A., and Kula K. (2019) Recent progress in the field of cycloaddition reactions involving conjugated nitroalkenes. Current Chem. Lett., 8 (1), 13-38.
22 Domingo L. R., Ríos-Gutiérrez M., Silvi B., and Pérez P. (2018) The mysticism of pericyclic reactions: A contemporary rationalisation of organic reactivity based on electron density analysis. Eur. J. Org. Chem., 2018 (9), 1107-1120.
23 Jasiński R., Jasińska E., and Dresler E. (2017) A DFT computational study of the molecular mechanism of [3+2] cycloaddition reactions between nitroethene and benzonitrile N-oxides. J. Mol. Model., 23, 13-21.
24 Łapczuk-Krygier A., Ponikiewski Ł., and Jasiński R. (2014) The crystal structure of (1RS,4RS,5RS, 6SR)-5-cyano-5-nitro-6-phenylbicyclo[2.2.1]hept-2-ene. Crystallogr. Rep., 59 (7), 961-963.
25 Ono N. (2001) The nitro group in organic synthesis, 1st Ed, Wiley-VCH, New York.
26 Feuer H. (2001) Nitrile oxides, nitrones, and nitronates in organic synthesis, 2nd Ed, John Wiley & Sons, New Jersey.
27 Jasiński R., Kula K., Kącka A. and Mirosław B. (2017) Unexpected course of reaction between (E)-2-aryl-1-cyano-1-nitroethenes and diazafluorene: why is there no 1,3-dipolar cycloaddition? Monats. Chem., 148 (5), 909-915.
28 Boguszewska-Czubara A., Kula K., Wnorowski A., Biernasiuk A., Popiołek Ł., Miodowski D., Demchuk O. M., and Jasiński R. (2019) Novel functionalized β-nitrostyrenes: Promising candidates for new antibacterial drugs. Saudi Pharm. J., 27 (4), 593-601.
29 Bigotti S., Malpezzi L., Molteni M., Mele A. Panzeri W., and Zanda M. (2009) Functionalized fluoroalkyl heterocycles by 1,3-dipolar cycloadditions with γ-fluoro-α-nitroalkenes. Tetrahedron Lett., 50 (21), 2540-2542.
30 Frisch M. J., Trucks G. W., Schlegel H. B., Scuseria G. E., Robb M. A., Cheeseman J. R., Scalmani G., Barone V., Mennucci B., Petersson G. A., Nakatsuji H., Caricato M., Li X., Hratchian H. P., Izmaylov A. F., Bloino J., Zheng G., Sonnenberg J. L., Hada M., Ehara M., Toyota K., Fukuda R., Hasegawa J., Ishida M., Nakajima T., Honda Y., Kitao O., Nakai H., Vreven T., Montgomery J. A. Jr., Peralta J. E., Ogliaro F., Bearpark M., Heyd J. J., Brothers E., Kudin K. N., Staroverov V. N., Keith T., Kobayashi R., Normand J., Raghavachari K., Rendell A., Burant J. C., Iyengar S. S., Tomasi J., Cossi M., Rega N., Millam J. M., Klene M., Knox J. E., Cross J. B., Bakken V., Adamo C., Jaramillo J., Gomperts R., Stratmann R. E., Yazyev O., Austin A. J., Cammi R., Pomelli C., Ochterski J. W., Martin R. L., Morokuma K., Zakrzewski V. G., Voth G. A., Salvador P., Dannenberg J. J., Dapprich S., Daniels A. D., Farkas O., Foresman J. B., Ortiz J. V., Cioslowski J., and Fox D. J. (2013) Gaussian 16, Revision A.03. Gaussian Inc., Wallingford CT.
31 Parr R. G., and Yang W. (1979) Density-functional theory of atoms and molecules, in: Fukui K., and Pullman B. (Eds) Horizons of Quantum Chemistry. Springer, Netherlands, 5-15.
32 Pérez P., Domingo L. R., Aizman A., and Contreras R. (2007) The electrophilicity index in organic chemistry, in: Toro-Labbé A. (Eds) Theoretical and Computational Chemistry. Elsevier, Oxford, United Kingdom, 139-201.
33 Perez P., Domingo L. R., Aurell M. J., and Contreras R. (2003) Quantitative characterization of the global electrophilicity pattern of some reagents involved in 1,3-dipolar cycloaddition reactions. Tetrahedron, 59 (17), 3117-3125.
34 Pérez P., Domingo L. R., Duque-Noreña M., and Chamorro E. (2009) A condensed-to-atom nucleophilicity index. An application to the director effects on the electrophilic aromatic substitutions. J. Mol. Struct. (THEOCHEM), 895 (1-3), 86-91.
35 Domingo L. R., Perez P., and Saez J. A. (2013) Understanding the local reactivity in polar organic reactions through electrophilic and nucleophilic Parr functions. RSC Adv., 3 (5), 1486-1494.
36 Domingo L. R., and Saez J. A. (2009) Understanding the mechanism of polar Diels-Alder reactions. Org. Biomol. Chem., 7 (17), 3576-3583.
37 Kapłon K., Demchuk O. M., Wieczorek M., and Pietrusiewicz K. M. (2014) Brönsted acid catalyzed direct oxidative arylation of 1,4-naphthoquinone. Current Chem. Lett., 3 (1), 23-36.
38 Parr R. G., Szentpály L., and Liu S. (1999) Electrophilicity Index. J. Am. Chem. Soc., 121 (9), 1922-1924.
39 Domingo L. R., Ríos-Gutiérrez M., and Pérez P. (2016) Applications of the Conceptual Density Functional Theory Indices to Organic Chemistry Reactivity. Molecules, 2016, 21 (6), 748-769.
40 Jasiński R., Żmigrodzka M., Dresler E., and Kula K. (2017) A full regio- and stereoselective synthesis of 4-nitroisoxazolidines via stepwise [3+2] cycloaddition reactions between (Z)-C-(9-anthryl)-N-arylnitrones and (E)-3,3,3-trichloro-1-nitroprop-1-ene: Comprehensive experimental and theoretical study. J. Heterocycl. Chem., 54 (6), 3314-3320.
41 Kula K., Dobosz J., Jasiński J., Kącka-Zych A., Łapczuk-Krygier A., Mirosław B., and Demchuk O. M. (2020) [3+2] Cycloaddition of diaryldiazomethanes with (E)-3,3,3-trichloro-1-nitroprop-1-ene: An experimental, theoretical and structural study. J. Mol. Struct., 1203, 127473.
42 Mloston G., Jasiński R., Kula K., and Heimgartner H. (2020) A DFT study on the Barton–Kellogg reaction – The molecular mechanism of the formation of thiiranes in the reaction between diphenyldiazomethane and diaryl thioketones. Eur. J. Org. Chem., 2020 (2), 176-182.
43 Jasiński R. (2015) A stepwise, zwitterionic mechanism for the 1,3-dipolar cycloaddition between (Z)-C-4-methoxyphenyl-N-phenylnitrone and gem-chloronitroethene catalyzed by 1-butyl-3-methylimidazolium ionic liquid cations. Tetrahedron Lett., 56 (3), 532-535.
44 Cholewka E. (1995) Kinetic of reactions of benzonitrile N-oxides with trans-β-nitrostyrenes and thermolysis if obtained diarylisoxazolines, PhD dissertation, Cracow, Poland.
45 Boyer J. H. (1986) Nitroazoles. The C-Nitro Derivatives of Five-Membered N- and N,O- Heterocycles. VCH Publisher, United States.