Convenient synthesis of 4-hydroxy-1,2-dihydroquinoline-3-carboxylate derivatives and 4-oxo-1,2,3,4-tetrahydroquinoline-3-carboxylates

Bulletin of the Chemical Society of Japan

Volumn 76, Issue 6, 2003, Pages 1257-1259

  Kobayashi, Kazuhiro ^a   Nakahashi, Ryoji ^a   Mano, Masaaki ^a   Morikawa, Osamu ^a   Konishi, Hisatoshi ^a  

^a TOTTORI UNIVERSITY   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

CONDENSATION; DERIVATIVES; SYNTHESIS (CHEMICAL);

CLAISEN-TYPE CONDENSATION;

ORGANIC COMPOUNDS;

4 HYDROXY 1,2 DIHYDROQUINOLINE 3 CARBOXYLATE; 4 OXO 1,2,3,4 TETRAHYDROQUINOLINE 3 CARBOXYLATE; BENZOIC ACID DERIVATIVE; CARBOXYLIC ACID DERIVATIVE; MAGNESIUM; METHYL 2 (METHYLAMINO)BENZOATE; UNCLASSIFIED DRUG;

ARTICLE; CHEMICAL REACTION; CHEMICAL STRUCTURE; CLAISEN CONDENSATION; CONJUGATE; POLYMERIZATION; STRUCTURE ANALYSIS; SYNTHESIS;

EID: 0038389872     PISSN: 00092673     EISSN: None     Source Type: Journal    
DOI: 10.1246/bcsj.76.1257     Document Type: Article

References (22)

1. K. Kobayashi, H. Takabatake, T. Kitamura, O. Morikawa, and H. Konishi, Bull. Chem. Soc. Jpn., 70, 1697 (1997).
2. K. Kobayashi, R. Nakahashi, A. Shimizu, T. Kitamura, O. Morikawa, and H. Konishi, J. Chem. Soc., Perkin Trans. 1, 1999, 1547.
3. For recent reports on the synthesis and utility of 1,2-dihydroquinoline derivatives: S. Torii, H. Okumoto, and L. H. Xu, Tetrahedron Lett., 47, 665 (1991); L. Zhi, C. M. Tegley, E. A. Kallel, K. B. Marschke, D. E. Mais, M. M. Gottardis, and M. M. Jones, J. Med. Chem., 41, 291 (1998); J. P. Edwards, S. J. West, K. B. Marschke, D. E. Mais, M. M. Gottardis, and T. K. Jones, J. Med. Chem., 41, 303 (1998); L. G. Hamann, R. I. Higuchi, L. Zhi, J. P. Edwards, X.-N. Wang, K. B. Marschke, J. W. Kong, L. J. Farmer, and T. K. Jones, J. Med. Chem., 41, 623 (1998); J. P. Edwards, J. D. Ringgenberg, and T. K. Jones, Tetrahedron Lett., 39, 5139 (1998); H. Tokuyama, M. Sato, T. Ueda, and T. Fukuyama, Heterocycles, 54, 105 (2001); R. Yamaguchi, T. Nakayasu, B. Hatano, T. Nagura, S. Kozima, and K. Fujita, Tetrahedron, 57, 109 (2001); P. A. Evans, J. E. Robinson, and K. K. Mofett, Org. Lett., 3, 3269 (2001); M. Arisawa, C. Theeraladanon, A. Nishida, and M. Nakagawa, Tetrahedron Lett., 42, 8029 (2001). See also pertinent references cited in these papers and Refs. 1 and 2.
4. For recent reports on the synthesis and utility of 1,2-dihydroquinoline derivatives: S. Torii, H. Okumoto, and L. H. Xu, Tetrahedron Lett., 47, 665 (1991); L. Zhi, C. M. Tegley, E. A. Kallel, K. B. Marschke, D. E. Mais, M. M. Gottardis, and M. M. Jones, J. Med. Chem., 41, 291 (1998); J. P. Edwards, S. J. West, K. B. Marschke, D. E. Mais, M. M. Gottardis, and T. K. Jones, J. Med. Chem., 41, 303 (1998); L. G. Hamann, R. I. Higuchi, L. Zhi, J. P. Edwards, X.-N. Wang, K. B. Marschke, J. W. Kong, L. J. Farmer, and T. K. Jones, J. Med. Chem., 41, 623 (1998); J. P. Edwards, J. D. Ringgenberg, and T. K. Jones, Tetrahedron Lett., 39, 5139 (1998); H. Tokuyama, M. Sato, T. Ueda, and T. Fukuyama, Heterocycles, 54, 105 (2001); R. Yamaguchi, T. Nakayasu, B. Hatano, T. Nagura, S. Kozima, and K. Fujita, Tetrahedron, 57, 109 (2001); P. A. Evans, J. E. Robinson, and K. K. Mofett, Org. Lett., 3, 3269 (2001); M. Arisawa, C. Theeraladanon, A. Nishida, and M. Nakagawa, Tetrahedron Lett., 42, 8029 (2001). See also pertinent references cited in these papers and Refs. 1 and 2.
5. For recent reports on the synthesis and utility of 1,2-dihydroquinoline derivatives: S. Torii, H. Okumoto, and L. H. Xu, Tetrahedron Lett., 47, 665 (1991); L. Zhi, C. M. Tegley, E. A. Kallel, K. B. Marschke, D. E. Mais, M. M. Gottardis, and M. M. Jones, J. Med. Chem., 41, 291 (1998); J. P. Edwards, S. J. West, K. B. Marschke, D. E. Mais, M. M. Gottardis, and T. K. Jones, J. Med. Chem., 41, 303 (1998); L. G. Hamann, R. I. Higuchi, L. Zhi, J. P. Edwards, X.-N. Wang, K. B. Marschke, J. W. Kong, L. J. Farmer, and T. K. Jones, J. Med. Chem., 41, 623 (1998); J. P. Edwards, J. D. Ringgenberg, and T. K. Jones, Tetrahedron Lett., 39, 5139 (1998); H. Tokuyama, M. Sato, T. Ueda, and T. Fukuyama, Heterocycles, 54, 105 (2001); R. Yamaguchi, T. Nakayasu, B. Hatano, T. Nagura, S. Kozima, and K. Fujita, Tetrahedron, 57, 109 (2001); P. A. Evans, J. E. Robinson, and K. K. Mofett, Org. Lett., 3, 3269 (2001); M. Arisawa, C. Theeraladanon, A. Nishida, and M. Nakagawa, Tetrahedron Lett., 42, 8029 (2001). See also pertinent references cited in these papers and Refs. 1 and 2.
6. For recent reports on the synthesis and utility of 1,2-dihydroquinoline derivatives: S. Torii, H. Okumoto, and L. H. Xu, Tetrahedron Lett., 47, 665 (1991); L. Zhi, C. M. Tegley, E. A. Kallel, K. B. Marschke, D. E. Mais, M. M. Gottardis, and M. M. Jones, J. Med. Chem., 41, 291 (1998); J. P. Edwards, S. J. West, K. B. Marschke, D. E. Mais, M. M. Gottardis, and T. K. Jones, J. Med. Chem., 41, 303 (1998); L. G. Hamann, R. I. Higuchi, L. Zhi, J. P. Edwards, X.-N. Wang, K. B. Marschke, J. W. Kong, L. J. Farmer, and T. K. Jones, J. Med. Chem., 41, 623 (1998); J. P. Edwards, J. D. Ringgenberg, and T. K. Jones, Tetrahedron Lett., 39, 5139 (1998); H. Tokuyama, M. Sato, T. Ueda, and T. Fukuyama, Heterocycles, 54, 105 (2001); R. Yamaguchi, T. Nakayasu, B. Hatano, T. Nagura, S. Kozima, and K. Fujita, Tetrahedron, 57, 109 (2001); P. A. Evans, J. E. Robinson, and K. K. Mofett, Org. Lett., 3, 3269 (2001); M. Arisawa, C. Theeraladanon, A. Nishida, and M. Nakagawa, Tetrahedron Lett., 42, 8029 (2001). See also pertinent references cited in these papers and Refs. 1 and 2.
7. For recent reports on the synthesis and utility of 1,2-dihydroquinoline derivatives: S. Torii, H. Okumoto, and L. H. Xu, Tetrahedron Lett., 47, 665 (1991); L. Zhi, C. M. Tegley, E. A. Kallel, K. B. Marschke, D. E. Mais, M. M. Gottardis, and M. M. Jones, J. Med. Chem., 41, 291 (1998); J. P. Edwards, S. J. West, K. B. Marschke, D. E. Mais, M. M. Gottardis, and T. K. Jones, J. Med. Chem., 41, 303 (1998); L. G. Hamann, R. I. Higuchi, L. Zhi, J. P. Edwards, X.-N. Wang, K. B. Marschke, J. W. Kong, L. J. Farmer, and T. K. Jones, J. Med. Chem., 41, 623 (1998); J. P. Edwards, J. D. Ringgenberg, and T. K. Jones, Tetrahedron Lett., 39, 5139 (1998); H. Tokuyama, M. Sato, T. Ueda, and T. Fukuyama, Heterocycles, 54, 105 (2001); R. Yamaguchi, T. Nakayasu, B. Hatano, T. Nagura, S. Kozima, and K. Fujita, Tetrahedron, 57, 109 (2001); P. A. Evans, J. E. Robinson, and K. K. Mofett, Org. Lett., 3, 3269 (2001); M. Arisawa, C. Theeraladanon, A. Nishida, and M. Nakagawa, Tetrahedron Lett., 42, 8029 (2001). See also pertinent references cited in these papers and Refs. 1 and 2.
8. For recent reports on the synthesis and utility of 1,2-dihydroquinoline derivatives: S. Torii, H. Okumoto, and L. H. Xu, Tetrahedron Lett., 47, 665 (1991); L. Zhi, C. M. Tegley, E. A. Kallel, K. B. Marschke, D. E. Mais, M. M. Gottardis, and M. M. Jones, J. Med. Chem., 41, 291 (1998); J. P. Edwards, S. J. West, K. B. Marschke, D. E. Mais, M. M. Gottardis, and T. K. Jones, J. Med. Chem., 41, 303 (1998); L. G. Hamann, R. I. Higuchi, L. Zhi, J. P. Edwards, X.-N. Wang, K. B. Marschke, J. W. Kong, L. J. Farmer, and T. K. Jones, J. Med. Chem., 41, 623 (1998); J. P. Edwards, J. D. Ringgenberg, and T. K. Jones, Tetrahedron Lett., 39, 5139 (1998); H. Tokuyama, M. Sato, T. Ueda, and T. Fukuyama, Heterocycles, 54, 105 (2001); R. Yamaguchi, T. Nakayasu, B. Hatano, T. Nagura, S. Kozima, and K. Fujita, Tetrahedron, 57, 109 (2001); P. A. Evans, J. E. Robinson, and K. K. Mofett, Org. Lett., 3, 3269 (2001); M. Arisawa, C. Theeraladanon, A. Nishida, and M. Nakagawa, Tetrahedron Lett., 42, 8029 (2001). See also pertinent references cited in these papers and Refs. 1 and 2.
9. For recent reports on the synthesis and utility of 1,2-dihydroquinoline derivatives: S. Torii, H. Okumoto, and L. H. Xu, Tetrahedron Lett., 47, 665 (1991); L. Zhi, C. M. Tegley, E. A. Kallel, K. B. Marschke, D. E. Mais, M. M. Gottardis, and M. M. Jones, J. Med. Chem., 41, 291 (1998); J. P. Edwards, S. J. West, K. B. Marschke, D. E. Mais, M. M. Gottardis, and T. K. Jones, J. Med. Chem., 41, 303 (1998); L. G. Hamann, R. I. Higuchi, L. Zhi, J. P. Edwards, X.-N. Wang, K. B. Marschke, J. W. Kong, L. J. Farmer, and T. K. Jones, J. Med. Chem., 41, 623 (1998); J. P. Edwards, J. D. Ringgenberg, and T. K. Jones, Tetrahedron Lett., 39, 5139 (1998); H. Tokuyama, M. Sato, T. Ueda, and T. Fukuyama, Heterocycles, 54, 105 (2001); R. Yamaguchi, T. Nakayasu, B. Hatano, T. Nagura, S. Kozima, and K. Fujita, Tetrahedron, 57, 109 (2001); P. A. Evans, J. E. Robinson, and K. K. Mofett, Org. Lett., 3, 3269 (2001); M. Arisawa, C. Theeraladanon, A. Nishida, and M. Nakagawa, Tetrahedron Lett., 42, 8029 (2001). See also pertinent references cited in these papers and Refs. 1 and 2.
10. For recent reports on the synthesis and utility of 1,2-dihydroquinoline derivatives: S. Torii, H. Okumoto, and L. H. Xu, Tetrahedron Lett., 47, 665 (1991); L. Zhi, C. M. Tegley, E. A. Kallel, K. B. Marschke, D. E. Mais, M. M. Gottardis, and M. M. Jones, J. Med. Chem., 41, 291 (1998); J. P. Edwards, S. J. West, K. B. Marschke, D. E. Mais, M. M. Gottardis, and T. K. Jones, J. Med. Chem., 41, 303 (1998); L. G. Hamann, R. I. Higuchi, L. Zhi, J. P. Edwards, X.-N. Wang, K. B. Marschke, J. W. Kong, L. J. Farmer, and T. K. Jones, J. Med. Chem., 41, 623 (1998); J. P. Edwards, J. D. Ringgenberg, and T. K. Jones, Tetrahedron Lett., 39, 5139 (1998); H. Tokuyama, M. Sato, T. Ueda, and T. Fukuyama, Heterocycles, 54, 105 (2001); R. Yamaguchi, T. Nakayasu, B. Hatano, T. Nagura, S. Kozima, and K. Fujita, Tetrahedron, 57, 109 (2001); P. A. Evans, J. E. Robinson, and K. K. Mofett, Org. Lett., 3, 3269 (2001); M. Arisawa, C. Theeraladanon, A. Nishida, and M. Nakagawa, Tetrahedron Lett., 42, 8029 (2001). See also pertinent references cited in these papers and Refs. 1 and 2.
11. For recent reports on the synthesis and utility of 1,2-dihydroquinoline derivatives: S. Torii, H. Okumoto, and L. H. Xu, Tetrahedron Lett., 47, 665 (1991); L. Zhi, C. M. Tegley, E. A. Kallel, K. B. Marschke, D. E. Mais, M. M. Gottardis, and M. M. Jones, J. Med. Chem., 41, 291 (1998); J. P. Edwards, S. J. West, K. B. Marschke, D. E. Mais, M. M. Gottardis, and T. K. Jones, J. Med. Chem., 41, 303 (1998); L. G. Hamann, R. I. Higuchi, L. Zhi, J. P. Edwards, X.-N. Wang, K. B. Marschke, J. W. Kong, L. J. Farmer, and T. K. Jones, J. Med. Chem., 41, 623 (1998); J. P. Edwards, J. D. Ringgenberg, and T. K. Jones, Tetrahedron Lett., 39, 5139 (1998); H. Tokuyama, M. Sato, T. Ueda, and T. Fukuyama, Heterocycles, 54, 105 (2001); R. Yamaguchi, T. Nakayasu, B. Hatano, T. Nagura, S. Kozima, and K. Fujita, Tetrahedron, 57, 109 (2001); P. A. Evans, J. E. Robinson, and K. K. Mofett, Org. Lett., 3, 3269 (2001); M. Arisawa, C. Theeraladanon, A. Nishida, and M. Nakagawa, Tetrahedron Lett., 42, 8029 (2001). See also pertinent references cited in these papers and Refs. 1 and 2.
12. Few reports on the synthesis of this class of compounds have been recorded: Z. B. Zheng and P. Dowd, Tetrahedron Lett., 34, 7709 (1993).
13. For recent syntheses of heterocycles using 2-aminobenzoic acid derivatives: M. Preshad, L. Chen, O. Repic, and T. J. Blachlock, Synth. Commun., 28, 2125 (1998); C. J. Lovely and H. Mahmud, Tetrahedron Lett., 40, 2079 (1999); D. J. Connolly and P. J. Guiry, Synlett, 2001, 1707; P. Hradil, L. Kvapil, J. Hlavac, T. Weidlich, A. Lycka, and K. Lemr, J. Heterocycl., Chem., 37, 831 (2000); A. Madrigal, M. Grande, and C. Avandano, Tetrahedron: Asymmetry, 11, 3515 (2000); J. K. Son, S. I. Kim, and Y. Jahng, Heterocycles, 55, 1981 (2001); J. Gimiene, D. Gueyrard, A. Tatibouët, A. Sackus, and P. Rollin, Tetrahedron Lett., 42, 2977 (2001); M. S. Khajavi, A. A. Mohammadi, and S. S. S. Hosseini, Synth. Commun., 31, 3647 (2001); X. G. Li, X. Cheng, and Q. L. Zhou, Synth. Commun., 32, 2477 (2002).
14. For recent syntheses of heterocycles using 2-aminobenzoic acid derivatives: M. Preshad, L. Chen, O. Repic, and T. J. Blachlock, Synth. Commun., 28, 2125 (1998); C. J. Lovely and H. Mahmud, Tetrahedron Lett., 40, 2079 (1999); D. J. Connolly and P. J. Guiry, Synlett, 2001, 1707; P. Hradil, L. Kvapil, J. Hlavac, T. Weidlich, A. Lycka, and K. Lemr, J. Heterocycl., Chem., 37, 831 (2000); A. Madrigal, M. Grande, and C. Avandano, Tetrahedron: Asymmetry, 11, 3515 (2000); J. K. Son, S. I. Kim, and Y. Jahng, Heterocycles, 55, 1981 (2001); J. Gimiene, D. Gueyrard, A. Tatibouët, A. Sackus, and P. Rollin, Tetrahedron Lett., 42, 2977 (2001); M. S. Khajavi, A. A. Mohammadi, and S. S. S. Hosseini, Synth. Commun., 31, 3647 (2001); X. G. Li, X. Cheng, and Q. L. Zhou, Synth. Commun., 32, 2477 (2002).
15. For recent syntheses of heterocycles using 2-aminobenzoic acid derivatives: M. Preshad, L. Chen, O. Repic, and T. J. Blachlock, Synth. Commun., 28, 2125 (1998); C. J. Lovely and H. Mahmud, Tetrahedron Lett., 40, 2079 (1999); D. J. Connolly and P. J. Guiry, Synlett, 2001, 1707; P. Hradil, L. Kvapil, J. Hlavac, T. Weidlich, A. Lycka, and K. Lemr, J. Heterocycl., Chem., 37, 831 (2000); A. Madrigal, M. Grande, and C. Avandano, Tetrahedron: Asymmetry, 11, 3515 (2000); J. K. Son, S. I. Kim, and Y. Jahng, Heterocycles, 55, 1981 (2001); J. Gimiene, D. Gueyrard, A. Tatibouët, A. Sackus, and P. Rollin, Tetrahedron Lett., 42, 2977 (2001); M. S. Khajavi, A. A. Mohammadi, and S. S. S. Hosseini, Synth. Commun., 31, 3647 (2001); X. G. Li, X. Cheng, and Q. L. Zhou, Synth. Commun., 32, 2477 (2002).
16. For recent syntheses of heterocycles using 2-aminobenzoic acid derivatives: M. Preshad, L. Chen, O. Repic, and T. J. Blachlock, Synth. Commun., 28, 2125 (1998); C. J. Lovely and H. Mahmud, Tetrahedron Lett., 40, 2079 (1999); D. J. Connolly and P. J. Guiry, Synlett, 2001, 1707; P. Hradil, L. Kvapil, J. Hlavac, T. Weidlich, A. Lycka, and K. Lemr, J. Heterocycl., Chem., 37, 831 (2000); A. Madrigal, M. Grande, and C. Avandano, Tetrahedron: Asymmetry, 11, 3515 (2000); J. K. Son, S. I. Kim, and Y. Jahng, Heterocycles, 55, 1981 (2001); J. Gimiene, D. Gueyrard, A. Tatibouët, A. Sackus, and P. Rollin, Tetrahedron Lett., 42, 2977 (2001); M. S. Khajavi, A. A. Mohammadi, and S. S. S. Hosseini, Synth. Commun., 31, 3647 (2001); X. G. Li, X. Cheng, and Q. L. Zhou, Synth. Commun., 32, 2477 (2002).
17. For recent syntheses of heterocycles using 2-aminobenzoic acid derivatives: M. Preshad, L. Chen, O. Repic, and T. J. Blachlock, Synth. Commun., 28, 2125 (1998); C. J. Lovely and H. Mahmud, Tetrahedron Lett., 40, 2079 (1999); D. J. Connolly and P. J. Guiry, Synlett, 2001, 1707; P. Hradil, L. Kvapil, J. Hlavac, T. Weidlich, A. Lycka, and K. Lemr, J. Heterocycl., Chem., 37, 831 (2000); A. Madrigal, M. Grande, and C. Avandano, Tetrahedron: Asymmetry, 11, 3515 (2000); J. K. Son, S. I. Kim, and Y. Jahng, Heterocycles, 55, 1981 (2001); J. Gimiene, D. Gueyrard, A. Tatibouët, A. Sackus, and P. Rollin, Tetrahedron Lett., 42, 2977 (2001); M. S. Khajavi, A. A. Mohammadi, and S. S. S. Hosseini, Synth. Commun., 31, 3647 (2001); X. G. Li, X. Cheng, and Q. L. Zhou, Synth. Commun., 32, 2477 (2002).
18. For recent syntheses of heterocycles using 2-aminobenzoic acid derivatives: M. Preshad, L. Chen, O. Repic, and T. J. Blachlock, Synth. Commun., 28, 2125 (1998); C. J. Lovely and H. Mahmud, Tetrahedron Lett., 40, 2079 (1999); D. J. Connolly and P. J. Guiry, Synlett, 2001, 1707; P. Hradil, L. Kvapil, J. Hlavac, T. Weidlich, A. Lycka, and K. Lemr, J. Heterocycl., Chem., 37, 831 (2000); A. Madrigal, M. Grande, and C. Avandano, Tetrahedron: Asymmetry, 11, 3515 (2000); J. K. Son, S. I. Kim, and Y. Jahng, Heterocycles, 55, 1981 (2001); J. Gimiene, D. Gueyrard, A. Tatibouët, A. Sackus, and P. Rollin, Tetrahedron Lett., 42, 2977 (2001); M. S. Khajavi, A. A. Mohammadi, and S. S. S. Hosseini, Synth. Commun., 31, 3647 (2001); X. G. Li, X. Cheng, and Q. L. Zhou, Synth. Commun., 32, 2477 (2002).
19. For recent syntheses of heterocycles using 2-aminobenzoic acid derivatives: M. Preshad, L. Chen, O. Repic, and T. J. Blachlock, Synth. Commun., 28, 2125 (1998); C. J. Lovely and H. Mahmud, Tetrahedron Lett., 40, 2079 (1999); D. J. Connolly and P. J. Guiry, Synlett, 2001, 1707; P. Hradil, L. Kvapil, J. Hlavac, T. Weidlich, A. Lycka, and K. Lemr, J. Heterocycl., Chem., 37, 831 (2000); A. Madrigal, M. Grande, and C. Avandano, Tetrahedron: Asymmetry, 11, 3515 (2000); J. K. Son, S. I. Kim, and Y. Jahng, Heterocycles, 55, 1981 (2001); J. Gimiene, D. Gueyrard, A. Tatibouët, A. Sackus, and P. Rollin, Tetrahedron Lett., 42, 2977 (2001); M. S. Khajavi, A. A. Mohammadi, and S. S. S. Hosseini, Synth. Commun., 31, 3647 (2001); X. G. Li, X. Cheng, and Q. L. Zhou, Synth. Commun., 32, 2477 (2002).
20. For recent syntheses of heterocycles using 2-aminobenzoic acid derivatives: M. Preshad, L. Chen, O. Repic, and T. J. Blachlock, Synth. Commun., 28, 2125 (1998); C. J. Lovely and H. Mahmud, Tetrahedron Lett., 40, 2079 (1999); D. J. Connolly and P. J. Guiry, Synlett, 2001, 1707; P. Hradil, L. Kvapil, J. Hlavac, T. Weidlich, A. Lycka, and K. Lemr, J. Heterocycl., Chem., 37, 831 (2000); A. Madrigal, M. Grande, and C. Avandano, Tetrahedron: Asymmetry, 11, 3515 (2000); J. K. Son, S. I. Kim, and Y. Jahng, Heterocycles, 55, 1981 (2001); J. Gimiene, D. Gueyrard, A. Tatibouët, A. Sackus, and P. Rollin, Tetrahedron Lett., 42, 2977 (2001); M. S. Khajavi, A. A. Mohammadi, and S. S. S. Hosseini, Synth. Commun., 31, 3647 (2001); X. G. Li, X. Cheng, and Q. L. Zhou, Synth. Commun., 32, 2477 (2002).
21. For recent syntheses of heterocycles using 2-aminobenzoic acid derivatives: M. Preshad, L. Chen, O. Repic, and T. J. Blachlock, Synth. Commun., 28, 2125 (1998); C. J. Lovely and H. Mahmud, Tetrahedron Lett., 40, 2079 (1999); D. J. Connolly and P. J. Guiry, Synlett, 2001, 1707; P. Hradil, L. Kvapil, J. Hlavac, T. Weidlich, A. Lycka, and K. Lemr, J. Heterocycl., Chem., 37, 831 (2000); A. Madrigal, M. Grande, and C. Avandano, Tetrahedron: Asymmetry, 11, 3515 (2000); J. K. Son, S. I. Kim, and Y. Jahng, Heterocycles, 55, 1981 (2001); J. Gimiene, D. Gueyrard, A. Tatibouët, A. Sackus, and P. Rollin, Tetrahedron Lett., 42, 2977 (2001); M. S. Khajavi, A. A. Mohammadi, and S. S. S. Hosseini, Synth. Commun., 31, 3647 (2001); X. G. Li, X. Cheng, and Q. L. Zhou, Synth. Commun., 32, 2477 (2002).
22. When the reaction was carried out with an equimolar amounts of 2a, a small amount (ca. 20%) of the starting material 1 was recovered.