Synlett 2008(8): 1137-1140  
DOI: 10.1055/s-2008-1072719
LETTER
© Georg Thieme Verlag Stuttgart · New York

Sequential Claisen Rearrangement and Intramolecular Heck Reaction as a Route to Medium-Ring Oxacycle-Fused Heterocycles

Shital K. Chattopadhyay*, Kaushik Neogi, Sovan K. Singha, Rajat Dey
Department of Chemistry, University of Kalyani, Kalyani 741235, West Bengal, India
Fax: +91(33)25828282; e-Mail: skchatto@yahoo.com;
Further Information

Publication History

Received 17 September 2007
Publication Date:
16 April 2008 (online)

Abstract

A synthetic strategy based on tandem application of Claisen rearrangement and intramolecular Heck reaction as key steps has been developed for the synthesis of various hitherto unknown benzoxocine- and benzoxonine-fused coumarin and quinolone derivatives.

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All new compounds reported gave satisfactory spectroscopic and/or analytical data. Compound 8: mp 265-266 °C. IR (KBr): 1755, 1728, 1596, 1395, 1280, 1192, 1109, 1027 cm-1. 1H NMR (300 MHz, CDCl3): δ = 7.34-7.40 (m, 2 H), 7.29-7.32 (m, 1 H), 7.14-7.24 (m, 1 H), 7.13 (s, 1 H), 6.67 (s, 1 H), 6.21 (s, 1 H), 2.38 (s, 3 H), 2.33 (d, J = 1.2 Hz, 3 H), 2.28 (d, J = 1.2 Hz, 3 H). 13C NMR (75 MHz, CDCl3): δ = 164.2 (s), 162.4 (s), 151.8 (s), 151.1 (s), 131.2 (s), 130.8 (d), 128.2 (s), 128.0(d), 127.2 (s), 127.1 (s), 126.6 (d), 126.3 (d), 126.1 (s), 122.6 (d), 121.6 (d), 118.2 (s), 117.3 (s), 114.7 (d), 24.5 (q), 18.7 (q), 9.6 (q). MS (EI, 70 eV): m/z (%) = 332 (10) [M+], 224 (100). Anal. Calcd for C21H16O4: C, 75.89; H, 4.85. Found: C, 75.93; H, 5.01.
Compound 13: mp 205-206 °C. IR (KBr): 1710, 1624, 1588, 1379, 1275, 1078 cm-1. 1H NMR (300 MHz, CDCl3): δ = 7.55 (d, J = 8.6 Hz, 1 H), 7.32-7.37 (m, 2 H), 7.24-7.26 (m, 2 H), 7.11 (d, J = 8.7 Hz, 1 H), 6.55 (d, J = 11.0 Hz, 1 H), 6.22 (s, 1 H), 6.10 (dt, J = 8.5, 10.8 Hz, 1 H), 5.29 (s, 2 H), 3.26 (d, J = 8.5 Hz, 2 H), 2.44 (s, 3 H). 13C NMR (75 MHz, CDCl3): δ = 161.5 (s), 160.1 (s), 152.4 (s), 138.5 (s), 137.4 (s), 136.2 (s), 132.4 (d), 130.6 (d), 129.2 (d), 128.7 (d), 126.4 (d), 125.2 (s), 124.2 (d), 118.4 (d), 116.2 (d), 115.2 (s), 113.1 (d), 75.5 (t), 35.6 (t), 18.9 (q). MS (TOFMS, ES+): m/z = 327 [M + Na]. Anal. Calcd for C20H16O3: C, 78.93; H, 5.30. Found: C, 79.09; H, 5.26.
Compound 21: mp 168-169 °C. IR (KBr): 1710, 1605, 1451, 1299, 1147, 1107 cm-1. 1H NMR (300 MHz, CDCl3): δ = 7.50 (dd, J = 1.2, 7.8 Hz, 1 H), 7.36-7.40 (m, 2 H), 7.23-7.24 (m, 1 H), 7.19-7.22 (m, 2 H), 7.13-7.18 (m, 2 H), 5.45 (d,
J = 1.5 Hz, 1 H), 5.43 (s, 2 H), 5.21 (d, J = 1.0 Hz, 1 H), 3.95 (s, 2 H). 13C NMR (75 MHz, CDCl3): δ = 158.2 (s), 150.7 (s), 146.7 (s), 140.9 (s), 137.7 (s), 133.1 (s), 131.8 (s), 130.6 (s), 129.7 (d), 128.9 (d), 128.8 (d), 128.6 (d), 128.2 (d), 124.4 (d), 123.4 (d), 116.8 (d), 115.8 (t), 74.3 (t), 36.6 (t). MS (TOFMS ES+): m/z = 313 [M + Na]. Anal. Calcd for C19H14O3: C, 78.61; H, 4.86. Found: C, 78.80; H, 4.94.