Cesium carbonate → 2-(7-Methyl-3-oxo-2,3-dihydro-benzo[1,4]oxazin-4-yl)-propionic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

To a mixture of 7-methyl-4H-benzo[1,4]oxazin-3-one (14.1 g, 86 mmol) and Cs2CO3 (70.4 g, 216 mmol) in DMF (500 mL) was added ethyl 2-bromopropanoate (31.3 g, 173 mmol) at ambient temperature and the reaction mixture was heated to 70° C. for 3 h. The reaction mixture was cooled to ambient temperature and the DMF was removed in vacuo. Water (500 mL) was added to the residue and the aqueous solution was extracted with EtOAc (3×150 mL). The combined organic phase was washed with brine (100 mL) and dried over anhydrous Na2SO4, filtered and concentrated in vacuo. The residue was purified by column chromatography on silica gel (eluting with 10% EtOAc in petroleum ether) to give 2-(7-methyl-3-oxo-2,3-dihydro-benzo[1,4]oxazin-4-yl)-propionic acid ethyl ester as brown solid (22.2 g, 98%). TLC (eluting with 20% EtOAc/heptane) Rf=0.3.

Provenance & Evidence