Synlett 2003(3): 0357-0360
DOI: 10.1055/s-2003-37125
LETTER
© Georg Thieme Verlag Stuttgart · New York

Facile Synthesis of 3-Alkylidene-3H-isobenzofuranones from the Baylis-Hillman Reaction of 2-Carboxybenzaldehyde

Ka Young Lee, Jeong Mi Kim, Jae Nyoung Kim*
Department of Chemistry and Institute of Basic Science, Chonnam National University, Gwangju 500-757, Korea
Fax: +82(62)5303389; e-Mail: kimjn@chonnam.chonnam.ac.kr;
Further Information

Publication History

Received 10 December 2002
Publication Date:
07 February 2003 (online)

Abstract

Baylis-Hillman reaction of 2-carboxybenzaldehyde (1) and some activated alkenes 2 gave the enol lactone derivatives 4 in moderate yields. The stereochemistry of the enol lactones was elucidated.

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Representative spectroscopic data of 4a, 4e and 3g are as follows:
4a-E: white solid, mp 69-70 °C (lit. [5a] 71-73 °C); IR (KBr)1790, 1715, 1633 cm-1; 1H NMR (CDCl3) δ 1.39 (t,
J = 7.1 Hz, 3 H), 2.27 (s, 3 H), 4.36 (q, J = 7.1 Hz, 2 H), 7.60 (t, J = 7.5 Hz, 1 H), 7.74 (m, 1 H), 7.94 (m, 1 H), 8.56 (d,
J = 8.1 Hz, 1 H); 13C NMR (CDCl3) δ 13.19, 13.88, 60.36, 112.00, 124.32, 125.17, 125.44, 129.94, 133.88, 135.81, 150.58, 164.87, 166.23; Mass (70 eV) m/z (rel. intensity) 77(45), 103(46), 131(46), 149(82), 158(94), 187(100), 232 (M+, 82).
4e-E: white solid, mp 103-104 °C (lit. [4c] 115-120 °C); IR (KBr) 1779, 1695 cm-1; 1H NMR (CDCl3) δ 2.33 (s, 3 H), 2.48 (s, 3 H), 7.59 (td, J = 7.5 and 0.9 Hz, 1 H), 7.70 (td,
J = 7.5 Hz and 1.2 Hz, 1 H), 7.93 (m, 1 H), 8.24 (d, J = 8.0 Hz, 1 H); 13C NMR (CDCl3) δ 15.15, 29.65, 120.11, 125.19, 125.35, 126.04, 131.03, 134.95, 136.93, 148.65, 166.01, 201.17; Mass (70 eV) m/z (rel. intensity) 43(32), 77(23), 103(27), 131(18), 160(100), 187(25), 202 (M+, 44).
4e-Z: white solid, mp 113-115 °C (lit. [4c] 104-105 °C); IR (KBr) 1780, 1662 cm-1; 1H NMR (CDCl3) δ 2.31 (s, 3 H), 2.72 (s, 3 H), 7.70 (td, J = 7.5 Hz and 0.9 Hz, 1 H), 7.83 (m, 1 H), 7.98 (d, J = 8.0 Hz, 1 H), 8.05 (d, J = 7.6 Hz, 1 H);
13C NMR (CDCl3) δ 12.69, 32.49, 118.13, 125.39, 125.68, 126.31, 131.27, 134.97, 138.96, 149.67, 165.30, 198.76; Mass (70 eV) m/z (rel. intensity) 43 (49), 77 (27), 103 (28), 131 (35), 160 (100), 187 (25), 202 (M+, 40).
3g: oil; IR (KBr) 1765, 1672 cm-1; 1H NMR (CDCl3) δ 1.90-2.14 (m, 2 H), 2.30-2.48 (m, 2 H), 2.50-2.58 (m, 2 H), 6.43 (s, 1 H), 6.98 (t, J = 4.2 Hz, 1 H), 7.49-7.91 (m, 4 H); 13C NMR (CDCl3) δ 22.33, 25.62, 38.25, 77.39, 123.27, 124.92, 125.62, 129.23, 134.33, 135.75, 146.95, 149.57, 170.68, 198.17; Mass (70 eV) m/z (rel. intensity) 77 (48), 105 (53), 133 (66), 144 (55), 172 (100), 228 (M+, 79).

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As an example, the Rf values of 4e-E and 4e-Z are 0.27 and 0.25, respectively, in hexane-diethyl ether = 3:2 solvent system.