orange residue (mp 90-95 °C) which was chromatographed on a silica gel column (30 X 1 cm i.d.) by eluting with methylene chloride/ethyl acetate (15:1 v/v). Compound-containing fractions (TLC, solvent system a) were evaporated, yielding white, crystalline 12: 0.070 g (39%); mp 98-100 °C; Rj 0.53 (solvent system a); IR (KBr) 2120 cm"1 234(NC); NMR (CDC13) 2.50 (3, s, 6-CH3), 4.00 and 4.07 (6, 2 s, 4-OCH3 and 2-OCH3).
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