phosphoric acid; dimethyl sulfoxide; dicyclohexyl-carbodiimide 1.5 h; Ambient temperature;

1: 1) Me2SO4 / 1) 60-70 deg C, 2) 2-propanol, H2O, ice-salt cooling, then rt 2: 89 percent / K2CO3 / methanol / 2.5 h 3: 59 percent / DMSO, N,N'-dicyclohexylcarbodiimide, H3PO4 / 1.5 h / Ambient temperature View Scheme

1: 89 percent / K2CO3 / methanol / 2.5 h 2: 59 percent / DMSO, N,N'-dicyclohexylcarbodiimide, H3PO4 / 1.5 h / Ambient temperature View Scheme