4 A molecular sieve in diethyl ether 0.333333 h; Ambient temperature;

1: 95 percent / 1 h / 110 °C 2: tetrahydrofuran / 1 h / -70 °C 3: 1.) trifluoroacetic anhydride, 2.) 15percent aq. NaOH / 1.) CH2Cl2, r.t., 4 h, 2.) MeOH, r.t., 6 h 4: HCl / methanol / Ambient temperature View Scheme

dimethylsulfide; copper(I) bromide; lithium bromide 2.) THF, -70 deg C, 30 min; Yield given. Multistep reaction. Yields of byproduct given. Title compound not separated from byproducts;