6,7-dimethoxy-4H-isochromene-1,3-dione → HCID 86686089, compound

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Reaction Steps

4,5-Dimethoxyhomophthalic anhydride (9, 1.16 g, 5.2 mmol) was added to a solution of 8 (1 g, 5.2 mmol) in chloroform (10 mL) and the mixture was stirred for 2 h at room temperature. The precipitate was filtered, washed with chloroform (2×10 mL) and dried to yield acid cis 10 (750 mg, 35%): mp 212-213° C. (dec). IR (KBr) 1737, 1626, 1599, 1578 cm−1; 1H NMR (300 MHz, methanol-d4) δ 7.80 (s, 1 H), 7.51 (s, 1 H), 7.29 (m, 2 H), 7.11 (t, J=7.0 Hz, 1 H), 6.83 (m, 2 H), 5.33 (d, J=6.60 Hz, 1 H), 4.45 (d, J=6.60 Hz, 1 H), 3.80 (s, 3 H), 3.74 (s, 3 H), 3.65 (s, 3 H), 2.80 (s, 3 H); ESIMS m/z (rel intensity) 851 (35), 459 (13), 436 (100), 415 (6), 215 (15); ESIHRMS m/z MNa+ calcd. for C21H22N2O7, 437.1325; found, 437.1333.

Provenance & Evidence