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Compound 122 (5.56 g, 25.6 mmol) was dissolved in anhydrous chloroform. Bromine (4.5 g, 28.5 mmol) was added dropwise over 2 hours at 5°-8° C. Then the mixture was maintained for an additional 2 hours at the same temperature. After the usual workup, 6.9 g of white solid 123 was obtained (88% yield). m.p. 165°-6° C. (crystallized from ethyl acetate). IR cm-1 1710 (s, C=O), 1425, 1400 (s, C--O); MS m/z (%): 288 (M+, 100), 290 (M+2, 96); 1H NMR δ ppm 3.91 (s, 3H, OCH3), 4.14 (s, 3H, ArOCH3), 6.10 (s, 2H, OCH2O), 7.65 (s, 1H, 6-ArH); Anal. (C10H9O5Br) C, H, Br.

1. temperatureThen the mixture was maintained for an additional 2 hours at the same temperature