Yield: 70%

Reaction Conditions:

with toluene-4-sulfonic acid in tolueneHeating / reflux;

Steps:

162.2
To a solution of ethyl 4-oxo-2-(2,2,2-trifluoroacetyl)valerate (40 g, 167 mmol) in toluene (250 ml) was added p-toluenesulfonic acid (3 g, 16 mmol) and the mixture was heated under reflux overnight in a Dean-Stark apparatus under dehydrated conditions. The reaction solution was concentrated. The residue was purified by silica gel column chromatography (hexane:ethyl acetate=10:1) to give ethyl 5-methyl-2-(trifluoromethyl)-3-furancarboxylate (25.8 g, 70%). IR ν maxKBr cm-1: 1732, 1574.1H-NMR (CDCl3)δ: 1.35 (3H, t, J = 7.4 Hz), 2.35 (3H, s) , 4.32 (2H, q, J = 7.4 Hz), 4.62 (1H, s).

References:

Takeda Chemical Industries, Ltd. EP1362846, 2003, A1 Location in patent:Page/Page column 125