acetic anhydride in tetrahydrofuran 1 h;

dicyclohexyl-carbodiimide in ethyl acetate 1.) 1 h, 0 deg C, 2.) 24 h, r.t.;

1: 63 percent 2: 89 percent / dicyclohexylcarbodiimide / ethyl acetate / 1.) 1 h, 0 deg C, 2.) 24 h, r.t. View Scheme

1: With sodium tetrahydroborate in tetrahydrofuran T=0°C; 3.5 h; 2: With hydrogenchloride in tetrahydrofuran; water pH=~ 2; 3: With toluene-4-sulfonic acid in benzene 3 h; Heating / reflux;