Synlett 2003(3): 0402-0404
DOI: 10.1055/s-2003-37104
LETTER
© Georg Thieme Verlag Stuttgart · New York

‘Michael-Michael-Wittig’ Reactions of (2,4-Dioxobutylidene)phosphoranes with 3-Formylchromones

Peter Langer*, Edith Holtz
Institut für Chemie und Biochemie der Ernst-Moritz-Arndt-Universität Greifswald, Soldmannstrasse 16, 17487 Greifswald, Germany
e-Mail: peter.langer@uni-greifswald.de;
Further Information

Publication History

Received 5 January 2003
Publication Date:
07 February 2003 (online)

Abstract

4-(2′-Hydroxybenzoyl)salicylic esters and amides were prepared by domino ‘Michael-retro-Michael-Wittig’ reactions of (2,4-dioxobutylidene)triphenylphosphoranes with 3-formylchromones.

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Representative Experimental Procedure: A THF suspension (5 mL) of NaH (78 mg, 3.25 mmol) and 3b (556 mg, 1.43 mmol) was stirred under nitrogen atmosphere at 0 °C for 30 min. A THF solution (10 mL) of 2a (190 mg, 1.1 mmol) was added and the solution was stirred for 60 min at 0 °C. The reaction mixture was refluxed for 24 h, cooled and subsequently stirred for 12 h at 20 °C. To the mixture was added diethyl ether (30 mL), an aqueous solution of HCl (5 mL, 1 M) and a saturated solution of NaCl. The aqueous layer was separated and extracted with CH2Cl2 (3 × 10 mL). The combined organic layers were dried (MgSO4), filtered and the solvent of the filtrate was removed in vacuo. The residue was purified by column chromatography (silica gel, diethyl ether/petroleum ether = 1:20) to give 4b (52%) as a yellow solid. Spectroscopic data of 4b: 1H NMR (CDCl3, 250 MHz): δ = 1.42 (t, 3 J = 7 Hz, 3 H, CH3), 4.45 (q, 3 J = 7 Hz, 2 H, OCH 2CH3), 6.91 (dd, 3 J 1 = 7 Hz, 3 J 2 = 8 Hz, 1 H, Ar), 7.08 (d, 3 J = 8 Hz, 1 H, Ar), 7.10 (d, 3 J = 8 Hz, 1 H, Ar), 7.53 (dd, 3 J 1 = 7 Hz, 3 J 2 = 8 Hz, 1 H, Ar), 7.59 (d, 3 J = 8 Hz, 1 H, Ar), 7.84 (d, 3 J = 8 Hz, 1 H, Ar), 8.30 (s, 1 H, Ar), 11.34 (s, 1 H, OH), 11.87 (s, 1 H, OH). 13C NMR (CDCl3, 50 MHz): δ = 14.15 (CH3), 62.07 (CH2), 112.47, 119.03, 129.00 (C, Ar, ortho and para to OH), 117.74, 118.51, 118.70 (CH, Ar, ortho and para to OH), 132.36, 132.95, 136.18, 136.59 (CH, Ar, meta to OH), 163.00, 164.70, 169.61 (C, C-OH, CO2Et), 199.12 (C, CO). IR (KBr): 3178 (w), 3059 (w), 2987 (w), 2933 (w), 1683 (s), 1629 (s), 1589 (s), 1467 (m), 1444 (m), 1397 (m), 1343 (s), 1293 (s), 1262 (s), 1242 (s), 1176 (m), 1084 (m) cm-1. MS (70 eV): m/z (%) = 286 (100) [M+], 121(94). Anal. Calcd for C16H14O5: C, 67.31; H, 4.93. Found: C, 66.88; H, 5.18. All compounds gave satisfactory spectroscopic and analytical and/or high resolution mass data.