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resulted was allowed to warm to 70 °C and stirred for 3 h. The mix-
ture was then cooled to room temperature, after which EtOAc
(10 mL) and a saturated solution of NaHCO3(aq) (10 mL) were added
carefully. The aqueous layer was extracted with EtOAc (3 ꢃ 10 mL),
and the combined organic layers were washed successively with
saturated solutions of NaHCO3(aq) and NaCl(aq) after which it was
dried (MgSO4). After filtration the solvent was removed under re-
duced pressure and the solid residue purified by flash column
chromatography on silica gel using n-hexane/EtOAc (15:1) as the
eluent. The flavone was obtained in 97% (29 mg, 0.092 mmol) yield.
Rf: 0.51 on silica gel (n-hexane/EtOAc 6:1); mp = 187 °C; 1H
NMR (300 MHz, CDCl3) d 8.18 (d, J = 2.6 Hz, 1H), 7.82–7.85 (m,
2H), 7.62 (dd, J = 9.0, 2.6 Hz, 1H), 7.50–7.56 (m, 3H), 6.80 (s, 1H),
1,37 (s, 9H); 13C NMR (75 MHz, CDCl3) d 177.2, 163.9, 155.7,
154.5, 133.8, 131.1, 128.5, 126.2, 126.1, 125.1, 124.9, 119.8,
106.9, 35.1, 31.1 ppm; HRMS (ESI) (M+H)+ calcd for C19H18ClO2
313.0990, found: 313.0986.
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Acknowledgments
We thank Matthew E. Dudley, Marquette University, for techni-
cal advice and the NIH (in part) as well as The Research Growth Ini-
tiative of the University of Wisconsin-Milwaukee for financial
support. This catalytic process was developed based on the earlier
work of Liao4a and Tsuji.6c
References and notes
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