Br[CH:2]1[C:7](=O)[CH:6]([CH3:9])[CH2:5][O:4][CH2:3]1.[OH-].[NH4+:11].[CH2:12]([C:14]1[CH:22]=[C:21]([CH3:23])[C:20](C=O)=[CH:19][C:15]=1[C:16]([OH:18])=[O:17])[CH3:13].C[N:27]([CH3:30])C=O>>[CH2:12]([C:14]1[CH:22]=[C:21]([CH3:23])[C:20]([C:30]2[NH:27][C:2]3[CH2:3][O:4][CH2:5][CH:6]([CH3:9])[C:7]=3[N:11]=2)=[CH:19][C:15]=1[C:16]([OH:18])=[O:17])[CH3:13]Into around-bottom flask, was placed a solution of 3-bromo-5-methyldihydro-2H-pyran-4(3H)-one (compound 400.2, 800 mg, 4.14 mmol, 1.6 equiv) in N,N-dimethylformamide (5 mL). Ammonium hydroxide (25% NH3 in H2O) (530 mg, 7.8 mmol, 3.0 equiv), NH4OAc (904 mg, 11.7 mmol, 4.50 equiv) and 2-ethyl-5-formyl-4-methylbenzoic acid (compound 211.4, 500 mg, 2.60 mmol, 1.00 equiv) were added to the flask. The resulting mixture was stirred at 130° C. for 2 h, then concentrated in vacuo. The residue was purified by silica gel chromatography with dichloromethane/methanol (70/1) as the eluent to obtain the title compound as a white solid (30.0 mg, 2%).
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