dimethyl sulfate 1) 60-70 deg C, 2 h, 2) 2-propanol, H2O, ice-salt cooling, 30 min, then rt, 1 h; Yield given. Multistep reaction. Yields of byproduct given;

1: 53 percent / K2CO3 / methanol / 2.5 h 2: 76 percent / DMSO, N,N'-dicyclohexylcarbodiimide, H3PO4 / 1.5 h / Ambient temperature View Scheme

potassium carbonate in methanol 2.5 h;