HETEROCYCLES

Paper | Special issue | Vol. 90, No. 2, 2015, pp. 1072-1081
Received, 1st July, 2014, Accepted, 23rd July, 2014, Published online, 5th August, 2014.
DOI: 10.3987/COM-14-S(K)76

■ Facile and Convenient Syntheses for Fluorine-Containing Pyrazolo[4,3-c]quinolines, Isoxazoloquinolines, and 1,4-Diazepino[6,5-c]quinolines

Etsuji Okada,* Mizuki Hatakenaka, and Takushi Sakaemura

Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan

Abstract

N,N-Dimethyl-3-trifluoroacetyl-4-quinolylamine underwent an aromatic nucleophilic N-N exchange reaction with hydrazines followed by cyclocondensation to afford the corresponding novel fluorine-containing 1H- and 2H-pyrazolo[4,3-c]quinolines in good to high yields. This reaction could be extended to the synthesis of novel CF3-containing isoxazoloquinolines using hydroxylamine. Furthermore, the use of 1,2-ethylenediamine and 1,2-phenylenediamines gave the corresponding fluorine-containing 1,4-diazepino[6,5-c]quinoline derivatives in high yields.

INTRODUCTION
Pyrazolo[4,3-c]quinolines have attracted much attention because of their pharmacological properties. For example, they have demonstrated potential applications as antiproliferative,1,2 antitumor,1,3 allergy inhibit,2 anti-inflammatory,2 antiparkinsonian,4 analgesic,5 and antipyretic activities.5 Isoxazoloquinoline and the related derivatives show interesting biological activities such as antioxidant,6 analgesic,7 anticonvulsant,7 antiepileptic,7 anxiolytic,7 antidepressant,7,8 antimalarial,9 and antibacterial activities.10 1,4-Diazepino[6,5-c]quinoline derivatives are also important heterocyclic systems having interesting biological properties such as anti-alzheimer,11 antiproliferative,11 antitumor,11 antiviral,11 antibacterial,12 and HIV-1 reverse transcriptase inhibit activities.13 Besides, considerable attention in recent years has been paid to the development of new methodologies for the syntheses of many kinds of fluorine-containing heterocycles, since these compounds are now widely recognized as important organic materials showing interesting biological activities for their potential use in medicinal and agricultural scientific fields.14　　Thus, it would be very important to develop facile and convenient synthetic methods for novel fluorine-containing pyrazolo[4,3-c]quinolines, isoxazoloquinolines, and 1,4-diazepino[6,5-c]quinolines, which would be strongly expected to present new bioactivities or functionalities.
Previously, we have found that N,N-dimethyl-2,4-bis(trifluoroacetyl)-1-naphthylamine15 and N,N-dimethyl-5,7-bis(trifluoroacetyl)-8-quinolylamine16 undergoes N-N exchange reaction and the subsequent cyclization with various bifunctional N-nucleophiles to achieve the facile syntheses of naphthalene15 and quinoline16 fused heterocycles bearing trifluoromethyl groups. Recently, we have reported the synthesis of N,N-dimethyl-3-trifluoroacetyl-4-quinolylamine (1) and its aromatic nucleophilic N-N exchange reactions with amines to give the corresponding 3-trifluoroacetyl-4-quinolylamines in high yields.17,18 Later, we succeeded in applying this type of aromatic nucleophilic N-N exchange reaction to the simple synthesis of CF3-containing heterocycles having a quinoline skeleton such as dibenzo[b,h][1,6]naphthyridines by the combination of N-N exchange and acid catalyzed cyclization.19 In connection with this work, we wish to report the facile and convenient syntheses of novel fluorine-containing pyrazolo[4,3-c]quinolines (2, 3), isoxazolo[4,3-c]quinolines (5), and 1,4-diazepino[6,5-c]quinolines (8, 9) through the N-N exchange reaction and cyclization of 1 with bifunctional N-nucleophiles such as hydrazines, hydroxylamine, and 1,2-diamines. Furthermore, we also report the synthetic method for isoxazolo[4,5-c]quinoline derivative (7), the regioisomer of 5, from 3-trifluoroacetyl-4-quinolylamine (6) with hydroxylamine hydrochloride.

RESULTS AND DISCUSSION
Firstly, we examined the reaction of 1 with hydrazines (Scheme 1 and Table 1). Reaction of 1 with hydrazine monohydrate proceeded easily at room temperature for 4 h in acetonitrile to afford the N-unsubstituted 1H-pyrazolo[4,3-c]quinoline (2a) in almost quantitative yield. A treatment of methylhydrazine at room temperature gave a mixture of the two regioisomers 2b/3b in a ratio of about 5:1. Interestingly, when the reaction was carried out in refluxing acetonitrile, the ratio changed to about 1:3 (yield: 87%). Separation of a mixture of 1H-isomer (2b) and 2H-isomer (3b) was easily effected by chromatography on a silica gel column. tert-Butylhydrazine hydrochloride reacted readily with 1 in the presence of triethylamine to provide solely the 2H-isomer (3c) in 95% yield. Like­wise, phenyl­hydrazine gave the corresponding 2-phenyl-2H-pyrazoloquinoli­nes (3d) regioselectively in 97% yield. In the case of p-nitrophenylhydrazine hydrochloride, the reaction required more forced conditions (3 equiv of hydrazine and the prolonged time to 24 h) to afford the corresponding 2-p-nitrophenyl-2H-pyrazoroquinoline derivative (3e) in good yield.

The structural discrimination between these two regioisomers 2 and 3, was definitely made by comparison of 13C-NMR spectral data with those of 1H- and 2H-isomers of benz[g]indazoles15 and pyrazolo[4,3-h]quinolines16 having trifluoromethyl group at the 3-position.
The possibility that the reaction proceeds via the prior formation of a hydrazone at the 2-trifluoroacetyl group followed by an intramolecular N-N exchange to give the cyclized product seems unlikely, since
the reaction of 1 with N,N-dimethylhydrazine gave the exchange product 4 and the corresponding hydrazone could not be detected (Scheme 2).

Hydroxylamine hydrochloride was also successfully used as a nucleophile in reaction with 1 to give 3-trifluoromethylisoxazolo[4,3-c]quinoline (5) in high yield (Scheme 3). Its possible structural isomer, the isoxazolo[4,5-c]quinoline derivative (7) was prepared from 3-trifluoroacetyl-4-quinolylamine (6)17,18 with hydroxylamine hydrochloride in refluxing pyridine for 4 h (Scheme 4). 13C-NMR spectrometry enabled discrimination between these two isomer. The trifluoromethyl-substituted carbon (at the 3-position) of 5 appeared at δ = 154.0, while the trifluoromethyl-substituted carbon (at the 3-position) of 7 gave a signal at δ = 149.9.
Finally, we attempted to carry out the reaction of 1 with 1,2-diamines (Scheme 5). Reaction of 1 with 1,2-ethylenediamine proceeded successfully for 1 h in refluxing acetonitrile to give the desired 5-(trifluoro­methyl)-2,3-dihydro-1H-[1,4]diazepino[6,5-c]quinoline (8) almost quantitatively without the formation of the intermediate cyclic hemiaminal. Aromatic diamines such as 1,2-phenylenediamine and its 4,5-dimethyl-substituted derivative also reacted with 1 under forced conditions (24 h in refluxing butyronitrile) to afford solely the corresponding diazepinoquinolines (9a and 9b) in high yields.
In summary, we succeeded in the reactions of 1 with various bifunctional N-nucleophiles and demonstrated a facile and convenient approach for the syntheses of 1H- and 2H-pyrazolo[4,3-c]quinolines (2, 3), isoxazolo[4,3-c]quinolines (5), and 1,4-diazepino[6,5-c]quinolines (8, 9) which are not easily

accessible by other methods. Furthermore, we also found that isoxazolo[4,5-c]quinolone derivative (7), structural isomer of 5, was easily prepared from 3-trifluoroacetyl-4-quinolylamine (6) with hydroxylamine hydrochloride. Evaluation of biological activities for all new compounds 2, 3, 5, and 7-9 is now under way.

EXPERIMENTAL
All reagents and solvents were purchased as reagent grade and used without further purification. Melting points were determined on an electrothermal digital melting point apparatus and are uncorrected. 1H NMR spectra were obtained with JEOL PMX 60SI (60 MHz) and Bruker Avance 500 (500 MHz) spectrometers and 13C NMR spectra were obtained with JEOL FX-90Q (22.5 MHz) and Bruker Avance 500 (125 MHz) spectrometers; TMS was used as an internal standard. IR spectra were recorded on Hitachi EPI-G3 and PerkinElmer Spectrum ONE spectrophotometers. Microanalyses were taken with a Yanaco CHN-Coder MT-5 analyzer.
1H- and 2H-Pyrazolo[4,3-c]quinolines 2 and 3; General Procedure
Using Hydrazine monohydrate, Methyl- and Phenylhydrazines; To a solution of 117,18 (268 mg, 1 mmol) in MeCN (7 mL) was added the appropriate hydrazines (1-3 mmol) and the mixture was stirred at room temperature-reflux temperature for 4-72 h. The solvent was evaporated in vacuo to give the practically pure product 2a. In the case of 2b, 3b, d, the crude product was chromatographed using n-hexane:EtOAc, 5:1 for 2b and n-hexane:EtOAc, 10:1 for 3b, d, as eluents.
Using tert-Butyl- and p-Nitrophenylhydrazine Hydrochlorides; To a solution of 1 (268 mg, 1 mmol) in MeCN (7 mL) was added hydrazine hydrochlorides (3 mmol) and Et3N (304 mg, 3 mmol) and the mixture was stirred at reflux temperature for 1-24 h. The solvent was evaporated under reduced pressure, and CH2Cl2 (50 mL) was added to the residue. The solution was washed with H2O (50 mL), and the organic layer was separated and dried (Na2SO4). The solvent was evaporated in vacuo and the crude product was chromatographed using n-hexane:EtOAc, 20:1 for 3c and n-hexane:EtOAc, 6:1 for 3e, as eluents.
3-(Trifluoromethyl)-1H-pyrazolo[4,3-c]quinoline (2a): mp 246 °C (dec.) (n-hexane/EtOAc); IR (KBr): 3064, 1172, 1143, 1109 cm-1; 1H NMR (DMSO-d6-CDCl3): δ 14.89-14.26 (br, 1H, NH), 9.28 (s, 1H, H-4), 8.44 (d, J = 7.4 Hz, 1H), 8.25 (d, J = 7.4 Hz, 1H), 7.79 (t, J = 7.4 Hz, 1H), 7.69 (t, J = 7.4 Hz, 1H); 13C NMR (DMSO-d6-CDCl3): 143.6, 142.6, 140.6, 134.9 (q, JCF = 38.7 Hz), 128.6, 128.3, 126.3, 121.1, 120.6 (q, JCF = 268.5 Hz), 114.2, 112.0. Anal. Calcd for C11H6F3N3: C, 55.70; H, 2.55; N, 17.72. Found: C, 55.49; H, 2.78; N, 17.84.
3-(Trifluoromethyl)-1-methyl-1H-pyrazolo[4,3-c]quinoline (2b): mp 137-138 °C (n-hexane/EtOAc); IR (KBr): 1180, 1133, 1098 cm-1; 1H NMR (CDCl3): δ 9.25 (s, 1H, H-4), 8.37 (d, J = 7.5 Hz, 1H), 8.30 (d, J = 7.5 Hz, 1H), 7.82 (t, J = 7.5 Hz, 1H), 7.73 (t, J = 7.5 Hz, 1H), 4.57 (s, 3H, CH3); 13C NMR (CDCl3): 145.4, 141.1, 139.7, 134.6 (q, JCF = 39.1 Hz), 130.6, 129.2, 127.4, 121.4 (q, JCF = 269.8 Hz), 120.9, 115.7, 114.5, 40.7. Anal. Calcd for C12H8F3N3: C, 57.37; H, 3.21; N, 16.73. Found: C, 57.19; H, 3.24; N, 16.88.
3-(Trifluoromethyl)-2-methyl-2H-pyrazolo[4,3-c]quinoline (3b): mp 116-117 °C (n-hexane/EtOAc); IR (KBr): 1184, 1121, 1109 cm-1; 1H NMR (CDCl3): δ 9.24 (s, 1H, H-4), 8.50 (d, J = 7.7 Hz, 1H), 8.18 (d, J = 7.7 Hz, 1H), 7.75 (t, J = 7.7 Hz, 1H), 7.68 (t, J = 7.7 Hz, 1H), 4.38 (s, 3H, CH3); 13C NMR (CDCl3): 146.2, 144.5, 144.3, 130.0, 128.9, 127.6, 125.3 (q, JCF = 40.3 Hz), 121.8, 120.6 (q, JCF = 269.8 Hz), 119.2, 115.0, 39.4. Anal. Calcd for C12H8F3N3: C, 57.37; H, 3.21; N, 16.73. Found: C, 57.35; H, 3.39; N, 16.43.
2-tert-Butyl-3-(trifluoromethyl)-2H-pyrazolo[4,3-c]quinoline (3c): mp 83-84 °C (n-hexane/EtOAc); IR (KBr): 1180, 1155, 1122 cm-1; 1H NMR (CDCl3): δ 9.28 (s, 1H, H-4), 8.55 (d, J = 7.5 Hz, 1H), 8.14 (d, J = 7.5 Hz, 1H), 7.72 (t, J = 7.5 Hz, 1H), 7.65 (t, J = 7.5 Hz, 1H), 1.88 (s, 9H, CH3); 13C NMR (CDCl3): 145.7 (q, JCF = 4.9 Hz), 144.4, 144.2, 130.0, 128.8, 127.5, 124.8 (q, JCF = 41.5 Hz), 121.9, 121.2 (q, JCF = 268.6 Hz), 119.8, 117.3, 66.1, 30.0. Anal. Calcd for C15H14F3N3: C, 61.43; H, 4.81; N, 14.33. Found: C, 61.43; H, 4.91; N, 14.23.
3-(Trifluoromethyl)-2-phenyl-2H-pyrazolo[4,3-c]quinoline (3d): mp 162-163 °C (n-hexane/EtOAc); IR (KBr): 1182, 1128, 1109 cm-1; 1H NMR (CDCl3): δ 9.34 (s, 1H, H-4), 8.57 (d, J = 7.7 Hz, 1H), 8.20 (d, J = 7.7 Hz, 1H), 7.78 (t, J = 7.7 Hz, 1H), 7.68 (t, J = 7.7 Hz, 1H), 7.65-7.54 (m, 5H, C6H5); 13C NMR (CDCl3): 147.2, 145.2, 144.5, 138.9, 130.4, 130.1, 129.5, 129.3, 127.9, 126.5 (q, JCF = 41.0 Hz), 126.2, 122.1, 120.1 (q, JCF = 270.4 Hz), 119.2, 115.6. Anal. Calcd for C17H10F3N3: C, 65.18; H, 3.22; N, 13.41. Found: C, 65.25; H, 3.49; N, 13.18.
3-(Trifluoromethyl)-2-(4-nitrophenyl)-2H-pyrazolo[4,3-c]quinoline (3e): mp 165-166 °C (n-hexane/EtOAc); IR (KBr): 1530, 1351, 1194, 1137, 1111 cm-1; 1H NMR (CDCl3): δ 9.35 (s, 1H, H-4), 8.56 (d, J = 7.5 Hz, 1H), 8.50 (d, J = 8.7 Hz, 2H), 8.22 (d, J = 7.5 Hz, 1H), 7.90 (d, J = 8.7 Hz, 1H), 7.82 (t, J = 7.5 Hz, 1H), 7.72 (t, J = 7.5 Hz, 1H); 13C NMR (CDCl3): 148.5, 147.9, 145.0, 144.5, 143.5, 130.2, 130.0, 128.3, 127.0, 126.6 (q, JCF = 41.5 Hz), 122.1, 119.9 (q, JCF = 270.8 Hz), 118.8, 116.1. Anal. Calcd for C17H9F3N4O2: C, 56.99; H, 2.53; N, 15.64. Found: C, 57.02; H, 2.71; N, 15.43.
2,2,2-Trifluoro-1-(4-[(dimethylamino)amino]quinolin-3-yl)ethanone (4)
To a solution of 1 (268 mg, 1 mmol) in MeCN (7 mL) was added N,N-dimethylhydrazine (72 mg, 1.2 mmol) and the mixture was heated in a sealed tube at 80 °C for 4 h. The solvent was evaporated in vacuo and the crude product was chromatographed using EtOAc as an eluent to give 4. 4: mp 178-179 °C (n-hexane/EtOAc); IR (KBr): 2845, 1689, 1191, 1120, 1060 cm-1; 1H NMR (CDCl3): δ 8.15 (s, 1H, H-2), 7.90 (d, J = 7.7 Hz, 1H), 7.82 (d, J = 7.7 Hz, 1H), 7.71 (t, J = 7.7 Hz, 1H), 7.48 (t, J = 7.7 Hz, 1H), 7.35 (br s, 1H, NH), 2.65 (s, 6H, N(CH3)2); 13C NMR (CDCl3): 182.0 (q, JCF = 41.0 Hz), 152.4, 146.7, 144.9, 130.9, 126.7, 125.3, 122.9, 117.7 (q, JCF = 285.9 Hz), 116.5, 108.7, 45.2. Anal. Calcd for C13H12F3N3O: C, 55.12; H, 4.27; N, 14.84. Found: C, 54.93; H, 4.34; N, 14.72.
3-(Trifluoromethyl)isoxazolo[4,3-c]quinoline (5)
A solution of hydroxylamine hydrochloride (83 mg, 1.2 mmol), Et3N (121 mg, 1.2 mmol), and 1 (268 mg, 1 mmol) in MeCN (7 mL) was stirred at reflux temperature for 1 h. The solvent was evaporated under reduced pressure, and CH2Cl2 (50 mL) was added to the residue. The solution was washed with H2O (50 mL), and the organic layer was separated and dried (Na2SO4). The solvent was evaporated in vacuo to give the practically pure product 5. 5: mp 143-144 °C (n-hexane/EtOAc); IR (KBr): 1208, 1176, 1147 cm-1; 1H NMR (CDCl3): δ 9.15 (s, 1H, H-4), 8.50 (d, J = 7.7 Hz, 1H), 8.14 (d, J = 7.7 Hz, 1H), 7.86 (t, J = 7.7 Hz, 1H), 7.73 (t, J = 7.7 Hz, 1H); 13C NMR (CDCl3): 155.7, 154.0 (q, JCF = 43.9 Hz), 144.8, 144.0, 132.2, 130.7, 129.4, 123.8, 118.3 (q, JCF = 271.0 Hz), 115.2, 111.7. Anal. Calcd for C11H5F3N2O: C, 55.47; H, 2.12; N, 11.76. Found: C, 55.23; H, 2.49; N, 11.89.
3-(Trifluoromethyl)isoxazolo[4,5-c]quinoline (7)
A solution of hydroxylamine hydrochloride (139 mg, 2 mmol) and 1 (268 mg, 1 mmol) in pyridine (7 mL) was stirred at reflux temperature for 4 h. The solvent was evaporated under reduced pressure, and CH2Cl2 (50 mL) was added to the residue. The solution was washed with H2O (50 mL), and the organic layer was separated and dried (Na2SO4). The solvent was evaporated in vacuo and the crude product was chromatographed using n-hexane:EtOAc, 15:1 as an eluent to give 7. 7: mp 118-119 °C (n-hexane/EtOAc); IR (KBr): 1181, 1153, 1112 cm-1; 1H NMR (CDCl3): δ 9.26 (s, 1H, H-4), 8.46 (d, J = 7.5 Hz, 1H), 8.35 (d, J = 7.5 Hz, 1H), 7.98 (t, J = 7.5 Hz, 1H), 7.83 (t, J = 7.5 Hz, 1H); 13C NMR (CDCl3): 167.1, 149.9 (q, JCF = 40.3 Hz), 147.7, 143.1, 132.1, 130.2, 128.7, 121.3, 120.0 (q, JCF = 271.0 Hz), 114.2, 110.7. Anal. Calcd for C11H5F3N2O: C, 55.47; H, 2.12; N, 11.76. Found: C, 55.45; H, 2.24; N, 11.89.
1,4-Diazepino[6,5-c]quinolines 8 and 9; General Procedure
Using 1,2-Ethylenediamine; To a solution of 1 (268 mg, 1 mmol) in MeCN (7 mL) was added 1,2-ethylenediamine (60 mg, 1 mmol) and the mixture was stirred at reflux temperature for 1 h. The solvent was evaporated in vacuo to give the practically pure product 8.
Using 1,2-Phenylenediamines; To a solution of 1 (268 mg, 1 mmol) in PrCN (7 mL) was added the appropriate 1,2-phenylenediamines (3 mmol) and the mixture was stirred at reflux temperature for 24 h. The solvent was evaporated under reduced pressure, and CH2Cl2 (50 mL) was added to the residue. The solution was washed with 1 N HCl (50 mL) and H2O (50 mL), and the organic layer was separated and dried (Na2SO4). The solvent was evaporated in vacuo and the crude product was chromatographed using n-hexane:EtOAc, 4:1 for 9a and n-hexane:EtOAc, 5:1 for 9b, as eluents.
5-(Trifluoromethyl)-2,3-dihydro-1H-[1,4]diazepino[6,5-c]quinoline (8): mp 231-232 °C (n-hexane/EtOAc); IR (KBr): 3234, 1183, 1154, 1120 cm-1; 1H NMR (DMSO-d6-CDCl3): δ 8.74 (s, 1H, H-6), 8.03 (d, J = 7.8 Hz, 1H), 7.94 (d, J = 7.8 Hz, 1H), 7.71 (t, J = 7.8 Hz, 1H), 7.48 (t, J = 7.8 Hz, 1H), 7.34 (br s, 1H, NH), 4.30-4.20 (m, 2H, CH2), 3.87-3.76 (m, 2H, CH2); 13C NMR (DMSO-d6-CDCl3): 158.2 (q, JCF = 33.5 Hz), 150.4, 147.5, 130.9, 129.4, 125.7, 122.0, 120.8 (q, JCF = 280.7 Hz), 119.3, 116.8, 102.4, 53.4, 48.6. Anal. Calcd for C13H10F3N3: C, 58.87; H, 3.80; N, 15.84. Found: C, 58.77; H, 3.98; N, 15.76.
7-Trifluoromethyl-13H-quino[4,​3-​b]​[1,​5]​benzodiazepine (9a): mp 144-145 °C (n-hexane/ EtOAc); IR (KBr): 3321, 1195, 1177, 1125 cm-1; 1H NMR (CDCl3): δ 8.74 (s, 1H, H-6), 8.06 (d, J = 7.7 Hz, 1H), 7.94 (d, J = 7.7 Hz, 1H), 7.78 (t, J = 7.7 Hz, 1H), 7.61 (t, J = 7.7 Hz, 1H), 7.28 (dd, J = 7.7, 1.3 Hz, 1H), 7.18 (td, J = 7.7, 1.3 Hz, 1H), 7.13 (td, J = 7.7, 1.3 Hz, 1H), 6.77 (dd, J = 7.7, 1.3 Hz, 1H), 6.19 (br s, 1H, NH); 13C NMR (CDCl3): 160.8, 156.3 (q, JCF = 33.2 Hz), 148.8, 147.9 (q, JCF = 3.7 Hz), 140.8, 139.0, 131.3, 129.5, 129.4, 129.1, 126.8, 125.1, 121.6, 120.6, 119.4 (q, JCF = 280.0 Hz), 113.2. Anal. Calcd for C17H10F3N3: C, 65.18; H, 3.22; N, 13.41. Found: C, 65.54; H, 3.26; N, 13.41.
10,11-Dimethyl-7-trifluoromethyl-13H-quino[4,​3-​b]​[1,​5]​benzodiazepine (9b): mp 136-137 °C (n-hexane/ EtOAc); IR (KBr): 3308, 1194, 1178, 1124 cm-1; 1H NMR (CDCl3): δ 8.72 (s, 1H, H-6), 8.06 (d, J = 7.9 Hz, 1H), 7.91 (d, J = 7.9 Hz, 1H), 7.78 (t, J = 7.9 Hz, 1H), 7.62 (t, J = 7.9 Hz, 1H), 7.07 (s, 1H, H-9), 6.53 (s, 1H, H-12), 5.98 (br s, 1H, NH), 2.19 (s, 6H, CH3); 13C NMR (CDCl3): 160.3, 155.7 (q, JCF = 33.9 Hz), 149.3, 148.7 (q, JCF = 3.7 Hz), 139.1, 137.9, 136.8, 134.1, 131.6, 130.9, 130.2, 127.2, 122.6, 120.2, 120.0 (q, JCF = 279.5 Hz), 119.9, 113.6, 19.1, 18.6. Anal. Calcd for C19H14F3N3: C, 66.86; H, 4.13; N, 12.31. Found: C, 66.81; H, 4.07; N, 12.48.

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