Cesium carbonate → Ethyl 2-(4-chloro-3-methylphenyl)-1,3-oxazole-4-carboxylate

Participants

Reaction Conditions

Reaction Steps

385 mg (1.44 mmol) of the compound from Example 25A and 319 mg (1.87 mmol) of 4-chloro-3-methylphenylboronic acid are initially charged in 12.7 ml of dry N-methyl-2-pyrrolidone. 105 mg (0.14 mmol) of bis(diphenylphosphino)ferrocenepalladium(II) chloride, 0.33 ml water and 940 mg (2.88 mmol) of cesium carbonate are then added. The reaction mixture is stirred at 50° C. for 4 h. The mixture is then cooled to RT, and 20 ml of ethyl acetate and 10 ml of water are added. The aqueous phase is extracted twice with in each case 20 ml of ethyl acetate. The combined organic phases are washed once with 10 ml of sat. aqueous sodium chloride solution and dried over magnesium sulfate. After filtration, the solvent is removed on a rotary evaporator. The residue is purified by preparative HPLC (column: YMC GEL ODS-AQ S-5/15 μm; mobile phase gradient: acetonitrile/water 10:90→95:5).

Provenance & Evidence