1: ethyl-α,α,α-trifluoroacetate With potassium tert-butylate in tetrahydrofuran; diethyl ether T=20°C; Claisen condensation; 0.75 h; 2: 3-methyl-butan-2-one in tetrahydrofuran; diethyl ether Claisen condensation; 3: With ammonium chloride in tetrahydrofuran; diethyl ether; water

sulfur(IV) fluoride T=20°C; 12 h; Yield given. Yields of byproduct given;