Quinoxaline Pyrazole N-Phenylethanamide

전체 글

(1)Journal of the Korean Chemical Society 2001, Vol. 45, No. 5 Printed in the Republic of Korea. Quinoxaline. Pyrazole N-Phenylethanamide.

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(4) Yoshihisa Kurasawa †. ‡.

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(6) (2001. 5. 2 ) †. ‡. Synthesis and Tautomerism of Pyrazoles and N-Phenylethanamides with Quinoxaline Ring Ho Sik Kim*, Kyung Ok Choi, Hyong Choul Lee, Sam Tag Kwag†, and Yoshihisa Kurasawa‡ Department of Chemistry, Catholic University of Taegu, Gyongsan 712-702, Korea † Division of Chemical Engineering, Pukyong National University, Pusan 608-739, Korea ‡ School of Pharmaceutical Sciences, Kitasato University, Tokyo 108-8641, Japan Received May 2, 2001). . 3-Methoxycarbonylmethylene-2-oxo-1,2,3,4-tetrahydroquinoxaline(7) hydrazine hydrate 3-hydrazinocarbonylmethylene-2-oxo-1,2,3,4-tetrahydroquinoxaline(8) !"#. $ 8 alkyl (ethoxymethylene)cyanoacetate% [(quinoxalin-2-ylidene)ethanoyl]-1H-pyrazole%(9)& !"', $ 9b& N-alkylaniline% N-alkyl-(quinoxalin-2-ylidene)-N-phenylethanamide% (10)& !"#. ()* $ 9, 10+ ,-./ enamine0 methylene imine0 12. 334 56 789:;<, 2=> 334?& H NMR @/ AB!"#. 1. ABSTRACT. The reaction of 3-methoxycarbonylmethylene-2-oxo-1,2,3,4-tetrahydroquinoxaline(7) with hydrazine hydrate gave 3-hydrazinocarbonylmethylene-2-oxo-1,2,3,4-tetrahydroquinoxaline(8). The reaction of compound 8 with alkyl (ethoxymethylene)cyanoacetates gave the [(quinoxalin-2-ylidene)ethanoyl]-1H-pyrazoles(9). The reaction of compound 9b with N-alkylanilines provided the N-alkyl-(quinoxalin-2-ylidene)-Nphenylethanamides(10). Compounds 9 and 10 showed the tautomerism between the enamine and methylene imine forms in solution. The tautomer ratios were determined by the 1H NMR.. . + cd. (2-thienyl)-2-chloroquinoxaline(4). CD EF@'G $H Pyrazole quinoxaline I JK=+ LMNOP Q2 R) STU, 2= IJ K=+ V$W X P; Y2 Q#' Z'R) S#. [& =\, 1-phenyl-3,5-diaryl-2-pyrazoline%(1) 3-methyl-1H-quinoxaline-2-thione(2)+ ]^ 78_#' `ab STU, 3-N-methylcarbamoyl-4chloro-1-(2,5-difluorophenyl)-5-phenylpyrazole(3) 31. 2,3. 4,5. , 3-bromo-. 1-(4-fluorophenyl)-5-[4-(methylsulfonyl)-phenyl]-. + ]ef , gG' 3-amino-2-quinoxalinecarbohydrazide imide 4-oxide(6); hij! 2 S#' kk Z'R) S#(Chart 1). l m./; pyrazole quinoxaline IJK=2 n o+ pq P ,J. 1,R' S#; 1m. rs t' quinoxaline 'G. pyrazole 'G u ?v pyrazolo[3,4-b]quinoxaline% pyrazolylpyrazole(5). 6. 7. 454.

(7) Quinoxaline. Pyrazole N-Phenylethanamide

(8) . 455. (:#. gG' Mass + Shimadzu GC/MS QP-5000 u QP-5050 & 1,!p (:#. 3-Methoxycarbonylmethylene-2-oxo-1,2,3,4-tetrahyd-. . Z'v T@ !"#.. 20-22. roquinoxaline(7). 3-Hydrazinocarbonylmethylene-2-oxo-1,2,3,4-tetrahyd-. . Z'v T@ !"#.. 23-25. roquinoxaline(8). Alkyl 5-amino-1-[2-(3-oxo-1,2,3,4-tetrahydroquinoxalin-2-ylidene)ethanoyl]-1H-pyrazole-4-carboxylate. (9) . %k}

(9) v 100 mL z¡.. $ 8(1 g, 4.60 mmol) alkyl (ethoxymethylene)cyanoacetate(6.88 mmol), gG' ¢£ 30 mL& ¤' }¥~¦./ 3§ %¨#. $ m©T@ kª « V v ¬B ip !' .®¯, n-°£ T@ ±²!p ³´µ ¬BH methyl 5-amino-1-[2-(3oxo-1,2,3,4-tetrahydroquinoxalin-2-ylidene)ethanoyl]-. (:#.. 1H-pyrazole-4-carboxylate(9a) 1.25 g(83%) Chart 1. o. mp: 274-275 C; IR(KBr, cm ): 3481, 3369, 1680,. %& w x S#. yz/ l ./; o-phenylenediamine dimethyl acetylenedicarboxylate(DMAD) (+ lactam typeH 3-methoxycarbonylmethylene-2-oxo-1,2,3,4-tetrahydroquinoxaline(7) {|$C@ !p V$W X C YT@ }R; quinoxaline 'G& * pyrazole% u N-phenylethanamide%& kk !"#. gG' w $= ~./ 334@ !; $= . w 334 56 H NMR <2 . >!p '!"#. 8-15. quinoxaline. 1. (DMSO-d6, δ): 12.02(s, 1H, NH), 11.96(s, 1H, NH), 7.77(s, 1H, pyrazole C3-H), 7.67-7.08(m, 4H, aromatic), 6.78(s, 1H, vinylic H), 3.74(s, 3H, CH3). The NH2 proton signal was not observed. Ethyl 5-amino-1-[2-(3-oxo-1,2,3,4-tetrahydroquinoxalin-. ; 1.30 g ³´µ ¬B) (:#. mp: 294-296 C; IR(KBr,. 2-ylidene)ethanoyl]-1H-pyrazole-4-carboxylate(9b) (83%,. o. cm−1): 3437, 3334, 1676, 1624, 1543, 1381, 1282;. MS(m/z): 341(M+); 1H NMR(DMSO-d6, δ): 12.01(s, 1H, NH), 11.96(s, 1H, NH), 7.76(s, 1H, pyrazole H), 4.22(q, J=7.0 Hz, 2H, CH2), 1.28(t, J=7.0 Hz,. l m./ 1,w + Bc!P ' 1,!"#. gG' alkyl (ethoxymethylene)cyanoacetate% ~./ ethyl (ethoxymethylene)cyanoacetate 2 > + !p 1,!"', ,; EP @ 1,!"#. ;+ Haake Buchler1> P ; AB @ (:TU ZB+ !P #. IR + Mattson Polaris FT-IR J& 1 , !p (:', H NMR + Varian Gemini200(200 MHz) u 300(300 MHz) & 1,!p 16-19. 2001, Vol. 45, No. 5. 1630, 1549, 1390, 1286; MS(m/z): 327(M+); 1H NMR. C3-H), 7.65-7.00(m, 4H, aromatic), 6.78(s, 1H, vinylic. . 1. −1. 3H, CH3). The NH2 proton signal was not observed. n-Propyl 5-amino-1-[2-(3-oxo-1,2,3,4-tetrahydroquinoxalin-2-ylidene)ethanoyl]-1H-pyrazole-4-carboxylate. ; 1.37 g(84%, ³´µ ¬B) (:#. mp: 268-. (9c). 269 oC; IR(KBr, cm−1): 3437, 3327, 1682, 1622, 1545, 1381, 1279; MS(m/z): 355(M+); 1H NMR (DMSOd6, δ): 12.02(s, 1H, NH), 11.96(s, 1H, NH), 7.77(s, 1H, pyrazole C3-H), 7.65-7.02(m, 4H, aromatic), 6.78(s, 1H, vinylic H), 4.13(t, J=6.6 Hz, 2H, CH2), 1.68 (sextet, J=6.8 Hz, 2H, CH2), 0.94(t, J=7.3 Hz, 3H, CH3). The NH2 proton signal was not observed..

(10) Yoshihisa Kurasawa. 456. Isopropyl 5-amino-1-[2-(3-oxo-1,2,3,4-tetrahydroqu-. (KBr, cm−1): 3298, 1653, 1599, 753, 693; MS(m/z):. inoxalin-2-ylidene)ethanoyl]-1H-pyrazole-4-carboxylate. 279(M+); 1H NMR(DMSO-d6, δ): 7.80-6.85(m, 9H,. (9d). aromatic), 5.88(s, 1/2H, vinylic H), 3.90(s, 1/2H, CH2).. ; 1.46 g(90%, ³´µ ¬B) (:#. mp: 270-. 271 oC; IR(KBr, cm−1): 3477, 3363, 1674, 1628,. NH protons were observed at 11.73(s), 11.55(s), 10.23. 1541, 1381, 1279; MS(m/z): 355(M+);. (s), 10.05(s) ppm.. 1. H NMR. (DMSO-d6, δ): 12.01(s, 1H, NH), 11.95(s, 1H, NH),. N-Methyl-2-[3-oxo-1,2,3,4-tetrahydroquinoxalin-2-. 6.78(s, 1H, vinylic H), 5.10(septet, J=6.3 Hz, 1H,. ylidene]-N-phenylethanamide(10b); 0.25 g(58%, *w ³´µ ¬B) (:#. mp: 195-197 C; IR(KBr, cm ):. CH), 1.31(d, J=6.1 Hz, 6H, 2CH3). The NH2 proton. 3362, 1681, 1628, 1384, 746, 695; MS(m/z): 293(M+);. signal was not observed.. 1. 7.73(s, 1H, pyrazole C3-H), 7.65-6.85(m, 4H, aromatic),. n-Butyl 5-amino-1-[2-(3-oxo-1,2,3,4-tetrahydroquinoxalin-2-ylidene)ethanoyl]-1H-pyrazole-4-carboxylate. ; 1.65 g(85%, ³´µ ¬B) (:#. mp: 208+. 1381, 1284, 1109; MS(m/z): 369(M );. 1. H NMR. (DMSO-d6, δ): 12.02(s, 1H, NH), 11.95(s, 1H, NH),. H NMR(DMSO-d6, δ): 12.10(s, 1H, NH), 11.54(s,. 1H, NH), 7.59-6.85(m, 9H, aromatic), 5.41(s, 1H, vinylic H), 3.27(s, 3H, CH3). N-Ethyl-2-[3-oxo-1,2,3,4-tetrahydroquinoxalin-2-ylidene]-. (9e). 210 oC; IR(KBr, cm−1): 3435, 2926, 1682, 1630, 1547,. −1. o. ; 0.16 g(59%, ³´µ ¬B). N-phenylethanamide(10c). (:#. mp: 176-178 C; IR(KBr, cm o. −1. ): 3363, 1683,. 1599, 1395, 1270, 758; MS(m/z): 307(M+); 1H NMR. 7.76(s, 1H, pyrazole C3-H), 7.62-6.98(m, 4H, aromatic),. (DMSO-d6, δ): 7.80-6.84(m, 9H, aromatic), 5.28(s, 1/. 6.78(s, 1H, vinylic H), 4.18(t, J=6.4 Hz, 2H, CH2),. 3H, vinylic H), 4.20(br, 2/3H, CH2), 3.72(q, J=7.0. 1.65(quintet, J=7.0 Hz, 2H, CH2), 1.37(sextet, J=7.8. Hz, 4/3H, CH2), 3.50(s, 2/3H, CH 2), 1.21(t, J=7.2. Hz, 2H, CH2), 0.92(t, J=7.2 Hz, 3H, CH3). The NH2. Hz, 1H, CH3), 1.07(t, J=7.2 Hz, 2H, CH3). NH protons. proton signal was not observed.. were observed at 12.30(s), 12.12(s), 11.53 (s) ppm.. 2-Ethylhexyl 5-amino-1-[2-(3-oxo-1,2,3,4-tetrahydroquinoxalin-2-ylidene)ethanoyl]-1H-pyrazole-4-carboxylate. ; 1.58 g(81%, ³´µ ¬B) (:#. mp: 254-255 C; o. (9f). −1. IR(KBr, cm ): 3447, 2926, 1684, 1626, 1542, 1378, 1276; MS(m/z): 425(M+);. 1. H NMR(DMSO-d6, δ):. 12.01(s, 1H, NH), 11.96(s, 1H, NH), 7.74(s, 1H,. N-n-Butyl-2-[3-oxo-1,2,3,4-tetrahydroquinoxalin-2-. ; 0.56 g(29%, ¿+. ylidene]-N-phenylethanamide(10e). ÀÁµ ¬B) (:#. mp: 200-202 C; IR(KBr, cm o. −1. ):. +. 3042, 1681, 1633, 1396, 1275, 744; MS(m/z): 335(M ); 1. H NMR(DMSO-d6, δ): 12.11(s, NH), 11.53(s, NH),. 7.60-6.85(m, 9H, aromatic), 5.29(s, 1H, vinylic H),. pyrazole C3-H), 7.60-7.05(m, 4H, aromatic), 6.78(s,. 3.72(t, J=7.0 Hz, 2H, -NCH2-), 1.45(quintet, J=3.0. 1H, vinylic H), 4.10(d, J=5.7 Hz, 2H, CH2), 1.75-1.55. Hz, 2H, CH2), 1.29(sextet, J=7.0 Hz, 2H, CH2), 0.86. (m, 2H, CH2), 1.45-1.17(m, 7H, CH(CH2)3), 0.85(t,. (t, J=7.2 Hz, 3H, CH3).. J=7.2 Hz, 6H, 2CH3). The NH2 proton signal was. . % k}

(11) v 100 mL z¡. $ 9b(0.5 g, 1.47 mmol) N-n-propylaniline(0.59 g, 4.4 mmol), g G' N,N-¹º»¥¶¼½ 25 mL& ¤' }¥~¦. / 3§ %¨#. ,& f|c¾ ª « .®¯ !p ip w p-. $ !p VÂ ¬B ip !"#. gG' 2 ¬B DÃ> Ä@@»¥ !p ÅÆÇ ,È r¡@É3gÊË(ÆÌ, ; .®¯: Ä@@»¥=1:10)@ Bc!"#. ,& f |c¾ ª « $ È VÂ ¬B ip !p ³´µ ¬BH $ 10d(0.07 g, 14%)& (:#. mp:. N-n-Propyl-2-[3-oxo-1,2,3,4-tetrahydroquinoxalin-. 2-ylidene]-N-phenylethanamide(10d). not observed. N-Alkyl-2-[3-oxo-1,2,3,4-tetrahydroquinoxalin-2-. . % k}

(12) v 100 mL z¡. $ 9b(0.20 g, 0.59 mmol) ¶·¸%(1.76 mmol), gG' N,N-¹º »¥¶¼½ 10 mL& ¤' }¥~¦./ 3§ % ¨#. $ m©T@ kª « ,& f|c¾ !', V v ¬B. f%& !p ip w « n-°£T@ ±²!p ³´µ ¬BH 2-[3-oxo-1,2,3,4ylidene]-N-phenylethanamide (10a-c,e). tetrahydroquinoxalin-2-ylidene]-N-phenylethanamide. (:#.. (10a) 0.12 g(73%). mp: 300 oC(dec.); IR. Journal of the Korean Chemical Society.


(14) . 457. 174-176 oC; IR(KBr, cm−1): 3049, 1681, 1618, 1393, 1275, 743; MS(m/z): 321(M+); 1H NMR(DMSO-d6, δ): 12.12(s, NH), 11.54(s, NH), 7.58-6.85(m, 9H, aromatic), 5.30(s, 1H, vinylic H), 3.69(t, J=7.0 Hz, 2H, -NCH2-), 1.47(sextet, J=7.4 Hz, 2H, CH2), 0.86 (t, J=7.2 Hz, 3H, CH3).. l ./; V$W X 2 }R; Í@Î [(quinoxalin-2-ylidene)ethanoyl]-1H-pyrazole% quinoxaline 'G. 3-arylcarbamoyl}& * N-phenylethanamide%> J !";<, 2=> @ ; #Ï o#. o-phenylenediamine DMAD 3-methoxycarbonylmethylene-2-oxo-1,2,3,4-tetrahy $ 7 droquinoxaline(7) !"TU, hydrazine hydrate 3-hydrazinocarbonylmethylene-2-oxo-1,2,3,4-tetrahydroquinoxaline(8) !"#. gG' $ 8 methyl, ethyl, n-propyl, isopropyl, n-butyl u 2-ethylhexyl À o+ `Ð}& * alkyl (ethoxymethylene)cyanoacetate% 9 'G . >È alkyl-5-amino-1-[2-(320-22. Scheme 1. 1H-pyrazole-4-carboxylate (9). ¾Ö $ 9 V × `#(Scheme 2).. $ 9; IR ./ 3481-3327 cm ./ 7 8Ø ¶¼³}> ÙÚ*Û ÜÝ H NMR ./ 7.77-7.73 ppm./ 78Ø pyrazole 'G 3Þ ®D> ß Ë2¡ u MS ÀT@ àH! "#. gG' $ 9~./ $ 9b& áWT@ â ã!p N-alkylaniline% N-alkyl-2-[3-oxo-. 1).. 1,2,3,4-tetrahydroquinoxalin-2-ylidene]-N-phenylethan-. 23-25. oxo-1,2,3,4-tetrahydroquinoxalin-2-ylidene)ethanoyl]-. % & !"#(Scheme. Ñ, $ 82 alkyl (ethoxymethylene)cyanoacetate % !p .®¯ w 2R\/ ~§K A V R', CDÒ> ?IÆ ÓÔ}> ® DÒ& Õ!p 9 'G T@ ~§K B&. −1. 1. % & !"#. lÊ; $ 7 N-alkylaniline% $ 10 !a' J!"T7 RP #. g. amide (10). Scheme 2 2001, Vol. 45, No. 5.

(15) Yoshihisa Kurasawa. 458. Scheme 3. k ï YT@ }!"# (Scheme 4). $ 9 ; H NMR ./ ?·} ß Ë2¡ 6.78 ppm./ 78ðT7 ¹ºñ ß Ë2¡ 7 87P + YT@/ enamine0(9C)T@ò w# ; Y ` S:#(Scheme 5). gq7 $ 10a 10c> ó; enamine0(10C) > ?·} ß Ë2¡ 5.88 ppm 5.28 ppm, methylene imine0 10D> ¹ºñ ß Ë2¡ 3.90 ppm 3.50 ppm./ kk 78ð#. gG' 2= 334> ? $ 10a> ó.; 50%: 50%,. $ 10c> ó; 33%: 67%@/ 2=+ DMSO-d ,-./ enamine0(10C) methylene imine0(10D) 2 o2 w#; Y ` S:#. wô, $ 10b, 10d, 10e> ó; ?·} ß Ë2¡ò 5.41 ppm, 5.30 ppm, 5.29 ppm./ kk 78Ø YT@ Z ¶ enamine0(10C)T@ò w#; Y `# 26,27. 1. Scheme 4. Ê/ $ 9b& aniline, N-methylaniline, N-ethylaniline, N-n-propylaniline u N-butylaniline kk . $ 9b> pyrazole 'G Ù. ¶·¸% v. $ 10 !"#. 2 ./ $ 9b> pyrazole 'G; ä+ 2}@/ åæ 2 ç ) è ` S:#(Scheme 3).. $ 10+ $ 9b> IR ./ 3437 cm 3334 cm ./ 78Ø 1é ¶ê%> 2Ì> N-H Ù Ú*Û ÜÝ~ w Ì ë)P', H NMR ./ 7.76 ppm./ 78Ø $ 9b> pyrazole 'G 3Þ ®D> ß Ë2¡ ë)* Y MS ÀT@ àH!"#. gì< $ 9, 10 o+ í& * $+ #Ï o+ îP 334 Ñ, enamine0(C) methylene imine0(D)> 334@ k −1. −1. 1. 6. (Scheme 6, Table 1).. 26> ¬ o2 Í@Î[(quinoxalin-2-ylidene)ethanoyl]-1H-pyrazole% quinoxaline 'G. 3-arylcarbamoyl}& * N-phenylethanamide%& !"T U, 2= $. w 334 56 '!"#.. Scheme 5 Journal of the Korean Chemical Society.


(17) . 459. Scheme 6 Table 1. NMR spectral data for compounds 10 Compound 10a 10b 10c 10d 10e. Tautomer Ratioa. Chemical Shift (δ ppm). C. D. Vinyl. Methylene. 150 100 133 100 100. 50 10 67 10 10. 5.88(s, 0.50H) 5.41(s, 1H) 5.28(s, 0.33H) 5.30(s, 1H) 5.29(s, 1H). 3.90(s, 0.50H) − 3.50(s, 0.67H) − −. a. Calculated from the integral curves of the vinylic H and methylene proton signals.. õT@ w $. w V$W X . w J ö *÷!p Ù]V$C u Ùø Ì|> X, p

(18) . rÈ/J ö R)ù ï Y2#.. 1. (a) Elguero, J. Comprehensive Heterocyclic Chemistry II; Katrizky, A. R., Rees, C. W., Scriven, E. F. V., Eds.; Pergamon Press: Oxford, U. K., 1996; Vol. 3, pp 1-75. (b) Sato, N. Comprehensive Heterocyclic Chemistry II; Katrizky, A. R., Rees, C. W., Scriven, E. F. V., Eds.; Pergamon Press: Oxford, U. K., 1996; Vol. 6, pp 234278. (c) Cheeseman, G. W. H.; Cookson, R. F. The Chemistry of Heterocyclic Compounds. Condensed Pyrazines; Weissberger, A., Taylor, E. C., Eds.; John Wiley & Sons: New York, U. S. A., 1979; pp 1-290. 2. Ankhiwala, M. D.; Hathi, M. V. Ind. J. Heterocyclic Chem. 1996, 5, 229. 2001, Vol. 45, No. 5. 3. Awad, I. M. A. Ind. J. Chem. 1991, 30B, 89. 4. Kudo, N.; Furuta, S.; Taniguchi, M.; Endo, T.; Sato, K. Chem. Pharm. Bull. 1999, 47, 857. 5. Makino, K.; Yoshioka, H. Heterocycles 1987, 26, 1215. 6. Tsuji, K.; Nakamura, K.; Konishi, N.; Tojo, T.; Ochi, T.; Senoh, H.; Matsuo, M. Chem. Pharm. Bull. 1997, 45, 987. 7. Monge, A.; Palop, J. A.; Urbasos, I.; Fern ndez-Alvarez, E. J. Heterocyclic Chem. 1989, 26, 1623. 8. Kurasawa, Y.; Kim, H. S.; Yonekura, K.; Takada, A.; Okamoto, Y. J. Heterocyclic Chem. 1989, 26, 857. 9. Kim, H. S.; Kurasawa, Y.; Takada, A. J. Heterocyclic Chem. 1989, 26, 1511. 10. Kim, H. S.; Kurasawa, Y.; Yoshii, C.; Masuyama, M.; Takada, A.; Okamoto. Y. J. Heterocyclic Chem. 1990, 27, 1111. 11. Kurasawa, Y.; Katoh, R.; Mori, F.; Fukuchi, M.; Okamoto, M.; Takada, A.; Kim, H. S.; Okamoto, Y. J. Heterocyclic Chem. 1992, 29, 1009..

(19) 460. Yoshihisa Kurasawa. 12. Kurasawa, Y.; Takano, A.; Kato, K.; Takada, A.; Kim, H. S.; Okamoto, Y. J. Heterocyclic Chem. 1996, 33, 757. 13. Kim, H. S.; Chung, J. Y.; Kim, E. K.; Park, Y. T.; Hong, Y. S.; Lee, M. K.; Kurasawa, Y.; Takada, A. J. Heterocyclic Chem. 1996, 33, 1855. 14. Kim, H. S.; Kwag, S. T.; Choi, K. O.; Okamoto, Y.; Kajiwara, S.; Fujiwara, N.; Kurasawa, Y. J. Heterocyclic Chem. 2000, 37, 103. 15. Kim, H. S.; Kwag, S. T. J. Korean Chem. Soc. 2000, 44, 229. 16. Fuson, R. C.; Parham, W. E.; Reed, L. J. J. Org. Chem. 1946, 11, 194. 17. Jones, R. G. J. Am. Chem. Soc. 1951, 73, 3684. 18. Jones, R. G. J. Am. Chem. Soc. 1952, 74, 4889. 19. Horning, E. C. Organic Syntheses, Parham, W. E., Reed, L. J., Eds.; John Wiley & Sons: New York,. USA., 1995; Collective Vol. 3, pp 395-397. 20. Iwanami, Y. Nippon Kagaku Zasshi 1961, 82, 778. 21. Weygard, F.; Steglich, W.; Tanner, H. Ann. Chem. 1962, 658, 128. 22. Suschitzky, H.; Wakefeld, B. J.; Whittker, R. A. J. Chem. Soc., Perkin Trans. 1, 1975, 401. 23. Kurasawa, Y.; Moritaki, Y.; Takada, A. Synthesis 1983, 238. 24. Kurasawa, Y.; Moritaki, Y.; Ebukuro, T.; Takada, A. Chem. Pharm. Bull. 1983, 31, 3897. 25. Kim, H. S.; Kim, E. K.; Kim, S. S.; Park, Y. T.; Hong, Y. S.; Kurasawa, Y. J. Heterocyclic Chem. 1997, 34, 39. 26. Kurasawa, Y.; Takada, A.; Kim, H. S. Heterocycles 1995, 41, 2057. 27. Kim, H. S.; Choi, K. O.; Kurasawa, Y. J. Korean Chem. Soc. 2000, 44, 435.. Journal of the Korean Chemical Society.

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Quinoxaline  Pyrazole  N-Phenylethanamide

Quinoxaline Pyrazole N-Phenylethanamide