Synlett 2004(7): 1309-1311  
DOI: 10.1055/s-2004-825595
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Microwave-Assisted Facile One-Pot Synthesis of Annelated Pyridines from β-Formyl Enamides via Henry Reaction

Apurba Chetia, Moanochet Longchar, Kushal C. Lekhok, Romesh C. Boruah*
Medicinal Chemistry Division, Regional Research Laboratory, Jorhat-785006, India
Fax: +91(376)2370011; e-Mail: rc_boruah@yahoo.co.in;
Further Information

Publication History

Received 11 January 2004
Publication Date:
10 May 2004 (online)

Abstract

The base-catalysed solid phase condensation of β-formyl enamides with nitromethane under microwave irradiation afforded a novel one-pot synthesis of pyridines via Henry reaction.

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All compounds gave satisfactory spectroscopic and analytical data. Spectral data of representative compound 10: Yield: 90%; mp 208-209 °C; Rf = 0.5 (toluene-EtOAc, 95:5). IR (KBr): 2938, 1730, 1521, 1373 cm-1. 1H NMR (CDCl3): δ = 8.02 (s, 1 H), 5.24 (br s, 1 H), 4.56 (br s, 1 H), 2.50 (s, 3 H), 2.20 (s, 3 H), 1.10 (s, 3 H), 1.09 (s, 3 H), 2.34-1.06 (m, 17 H). 13C NMR (CDCl3): δ = 177.2, 173.3, 170.5, 140.3, 135.2, 134.4, 128.6, 121.7, 73.7, 55.9, 55.5, 50.4, 38.1, 36.8, 33.3, 31.3, 30.7, 29.9, 28.9, 21.4, 20.5, 19.3, 17.2, 17.0, 14.5. MS (ESI): m/z = 447.53 [M+ + 23]. Anal. Calcd for C25H32O4N2: C, 70.73; H, 7.59; N, 6.51. Found: C, 71.26; H, 7.86; N, 6.05. Compound 14: Yield: 86%; mp 78-79 °C; Rf = 0.55 (toluene-EtOAc, 95:5). IR (KBr): 2945, 1525, 1360 cm-1. 1H NMR (CDCl3): δ = 8.05 (s, 1 H), 3.60-3.25 (m, 4 H), 2.05 (s, 3 H), 2.00-1.78 (m, 4 H). 13C NMR (CDCl3): δ = 169.5, 168.7, 140.5, 137.2, 136.5, 55.1, 54.8, 50.3, 47.6, 16.4. MS (ESI): m/z = 215.74 [M+ + 23]. Anal. Calcd for C10H12O2N2: C, 62.49; H, 6.29; N, 14.57. Found: C, 62.30; H, 6.56; N, 14.35.