[NH2:1][C:2]1[CH:3]=[CH:4][C:5]2[O:10][C:9]([CH3:12])([CH3:11])[CH:8]=[CH:7][C:6]=2[CH:13]=1.[C:14]([O-])(=O)[CH3:15].[NH4+:18].[CH2:19]=O.C(C=O)=O.[OH-].[NH4+]>C(O)(=O)C.CO>[CH3:12][C:9]1([CH3:11])[CH:8]=[CH:7][C:6]2[CH:13]=[C:2]([N:1]3[CH:15]=[CH:14][N:18]=[CH:19]3)[CH:3]=[CH:4][C:5]=2[O:10]1To a stirred solution of 20 g (0.11 mol) of 6-amino-2,2-dimethylbenzopyran and 70 g (0.91 mol) of ammonium acetate in 190 mL of acetic acid and 770 mL of MeOH at 65° C. is added dropwise over 0.5 h, a mixture of 11.1 g (0.14 mol) of formaldehyde and 20g (0.14 mol) of glyoxal. The mixture is stirred for 1 hour at 65° C., then poured onto 800 g of ice. The pH of the solution is adjusted to 10 by the addition of concentrated ammonium hydroxide. The mixture is extracted with dichloromethane (3×200 mL) and the combined organic extracts are dried with sodium sulfate, filtered and evaporated under reduced pressure. The resulting oil is subjected to chromatography on silica gel utilizing 3% methanol in dichloromethane as eluent. The eluates are analyzed utilizing thin layer chromatography and appropriate fractions are combined and evaporated to produce the title compound.
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