Synlett 2005(8): 1337-1339  
DOI: 10.1055/s-2005-868516
LETTER
© Georg Thieme Verlag Stuttgart · New York

Molecular-Iodine-Catalyzed One-Pot Synthesis of 1,5-Benzodiazepine Derivatives under Solvent-Free Conditions

Wei-Yi Chen*, Jun Lu
College of Chemistry and Chemical Engineering, Suzhou University, Suzhou, 215006, P. R. China
Fax: +86(512)65112371; e-Mail: suzhoucwy@163.com;
Further Information

Publication History

Received 7 March 2005
Publication Date:
03 May 2005 (online)

Abstract

2,3-Dihydro-1H-1,5-benzodiazepines have been syn­thesized from o-phenylenediamine (OPDA) and ketones under ­solvent-free conditions in the presence of a catalytic amount of ­molecular iodine. All of the ketones, including cyclic ketones and acyclic ketones, reacted smoothly with OPDA to furnish products. Compared to other reaction conditions, this new protocol has the ­advantage of excellent yield and short reaction time at room temperature.

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General Experimental Procedure: A mixture of OPDA (1 mmol), ketone (2 mmol), and iodine (0.1 mmol) were ground together in a mortar with a pestle at room temperature for several minutes. After completion of the reaction (TLC), the reaction was treated with aqueous Na2S2O3 to furnish the crude products, which were further purified by column chromatography.
3a: Mp 145-146 °C. IR (KBr): 3341, 1637, 1600 cm-1. 1H NMR (CDCl3): δ = 1.37 (s, 6 H), 2.25 (s, 2 H), 2.39 (s, 3 H), 3.44 (br s, 1 H), 6.64-7.41 (m, 4 H). 13C NMR (CDCl3): δ = 29.4, 30.8, 44.9, 68.1, 121.6, 122.3, 126.1, 126.8, 138.2, 140.9, 171.6.
3b: Mp 137-138 °C. IR (KBr): 3328, 1640, 1608 cm-1.1H NMR (CDCl3): δ = 0.98 (t, 3 H, J = 6.8 Hz), 1.24 (t, 3 H, J = 7.1 Hz), 1.72 (q, 2 H, J = 6.8 Hz), 2.18 (m, 2 H), 2.34 (s, 3 H), 2.71 (q, 2 H, J = 7.1 Hz), 3.28 (br s, 1 H), 6.78-7.33 (m, 4 H). 13C NMR (CDCl3): δ = 8.8, 11.2, 26.8, 35.9, 36.0, 42.3, 70.8, 121.9, 125.2, 126.4, 126.8, 137.6, 140.9, 175.8.
3c: Mp 142-144 °C. IR (KBr): 3320, 1638, 1596 cm-1.1H NMR (CDCl3): δ = 0.81-1.15 (m, 10 H), 1.22-1.42 (m, 4 H), 1.52-1.66 (m, 2 H), 2.38-2.56 (m, 2 H), 2.91 (q, 1 H, J = 7.0 Hz), 3.78 (br s, 1 H), 6.56-7.38 (m, 4 H). 13C NMR (CDCl3): δ = 7.6, 7.9, 11.9, 12.4, 28.1, 28.5, 35.5, 46.4, 68.4, 117.6, 118.2, 126.4, 132.7, 139.1, 142.2, 173.9.
3d: Mp 118-120 °C. IR (KBr): 3265, 1651, 1600 cm-1. 1H NMR (CDCl3): δ = 0.96-1.085 (m, 12 H), 1.34 (s, 3 H), 1.50-1.52 (m, 2 H), 1.66-1.75 (m, 1 H), 2.07-2.26 (m, 3 H), 2.25 (d, 2 H, J = 12.7 Hz), 6.60-7.15 (m, 4 H). 13C NMR (CDCl3): δ = 22.6, 22.9, 24.1, 24.8, 25.1, 26.2, 28.3, 43.4, 51.7, 51.9, 70.9, 121.4, 121.5, 125.3, 127.4, 137.9, 140.5, 173.9.
3e: Mp 150-152 °C. IR (KBr): 3268, 1640, 1601 cm-1. 1H NMR (CDCl3): δ = 1.81 (s, 3 H), 3.01 (d, 1 H, J = 12.8 Hz), 3.16 (d, 1 H, J = 12.8 Hz) 3.45 (br s, 1 H), 6.56-7.02 (m, 3 H), 7.14-7.40 (m, 7 H), 7.56-7.65 (m, 4 H). 13C NMR (CDCl3): δ = 29.8, 42.9, 73.5, 121.2, 121.5, 125.3, 126.1, 126.7, 126.9, 127.8, 128.2, 128.5, 129.6, 137.9, 139.4, 139.9, 147.5, 167.6.
3f: Mp 141-143 °C. IR (KBr): 3270, 1644, 1602 cm-1. 1H NMR (CDCl3): δ = 2.11 (s, 9 H,), 3.05 (d, 1 H, J = 13.6 Hz), 3.17 (d, 1 H, J = 13.6 Hz,), 3.60 (br s, 1 H), 7.12-7.61 (m, 11 H). 13C NMR (CDCl3): δ = 21.3, 24.4, 28.4, 29.0, 46.4, 52.5, 114.7, 122.2, 126.2, 127.1, 128.6, 132.7, 133.1, 133.6, 135.5, 136.1, 164.9.
3g: Mp 136-138 °C. IR (KBr): 3342, 1656, 1604 cm-1. 1H NMR (CDCl3): δ = 1.29-1.88 (m, 12 H), 2.31-2.58 (m, 3 H), 4.36 (br s, 1 H), 6.71-7.39 (m, 4 H). 13C NMR (CDCl3): δ = 23.5, 24.1, 24.4, 28.9, 33.4, 38.5, 39.4, 54.4, 67.3, 118.6, 119.5, 126.9, 132.3, 139.3, 143.3, 178.4.
3h: Mp 137-139 °C. IR (KBr): 3321, 1654, 1600 cm-1. 1H NMR (CDCl3): δ = 1.88-2.58 (m, 16 H), 2.46-2.79 (m, 3 H), 4.55 (br s, 1 H), 6.65-7.36 (m, 4 H). 13C NMR (CDCl3): δ = 21.5, 21.7, 23.3, 24.5, 25.4, 33.4, 34.4, 39.3, 40.5, 52.4, 63.2, 121.1, 121.4, 126.3, 129.7, 138.2, 142.4, 178.8.