[CH2:1]([O:3][C:4]([C:6]1[C:7]([CH3:14])=[CH:8][C:9](=O)[O:10][C:11]=1[CH3:12])=[O:5])[CH3:2].Cl.[NH2:16][NH2:17].CO>C([O-])([O-])=O.[K+].[K+]>[CH2:1]([O:3][C:4]([C:6]1[C:7]([CH3:14])=[CH:8][C:9](=[O:10])[N:16]([NH2:17])[C:11]=1[CH3:12])=[O:5])[CH3:2]A mixture of 4,6-dimethyl-2-oxo-2H-pyran-5-carboxylic acid ethyl ester (3.2 mL, 19 mmol) and hydrazine monohydrochloride (1.4 g, 20 mmol) in methanol (16 mL, 0.39 mmol) was heated under microwave irradiation for 2.5 hrs at 150° C. Reaction was taken up in sat. aq. K2CO3 (40 mL) and extracted with ethyl acetate (3×40 mL). The combined organic phases were washed with brine, dried over MgSO4, evaporated and purified by flash chromatography. Yield 7%. 1H NMR (500 MHz, CDCl3): 6.35 (s, 1H), 5.12 (s, 2H), 4.35 (q, J=7.1 Hz, 2H), 2.53 (s, 3H), 2.21 (s, 3H), 1.37 (t, J=7.1 Hz, 3H).
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