A mixture of 133 (0.3 g, 0.78 mmol), 2-ethyl-3-hydroxy-4H-pyran-4-one (0.11 g, 0.78 mmol) and K2CO3 (0.54 g, 3.91 mmol) in dimethylformamide (15 mL) was stirred at 80° C. for 6 hours under nitrogen atmosphere. After completion of the reaction the mixture was cooled to 25° C. and diluted with water (50 mL). The precipitated solid was filtered off and dried under vacuum to afford the title compound E19 as an off-white solid (0.2 g, 52%). mp 124-126° C.; HPLC: Inertsil ODS 3V (250×4.6 mm) 5 microns 50:50 [0.01 M KH2PO4 (0.1% TFA):CH3CN], 223 nm, Rt 18.47 min, 98.18% purity); MS (CI): m/z 486 (M+, 100), 382 (90).
