potassium carbonate in N,N-dimethyl-formamide T=85°C; 2 h;

1: Ursolic acid With potassium carbonate in N,N-dimethyl-formamide T=24°C; 1 h; 2: benzyl bromide in N,N-dimethyl-formamide 18 h;

1.1: 89 percent / PCC / CH2Cl2 / 24 h / 0 °C 2.1: 91 percent / H2SO4 / 100 °C 3.1: BH3*THF 3.2: 55 percent / aq. NaOH; H2O2 4.1: 100 percent / H2 / Pd/C / tetrahydrofuran / 20 °C View Scheme

1: methanesulfonyl chloride; pyridine; 4-(N,N-dimethlyamino)pyridine / |Reflux 2: 3-chloro-benzenecarboperoxoic acid; sodium hydrogencarbonate / dichloromethane 3: perchloric acid; water / tetrahydrofuran / 20 °C 4: hydrogen; palladium 10 on activated carbon / tetrahydrofuran View Scheme

1: With oxalyl dichloride; dimethyl sulfoxide in dichloromethane T=-78 - -50°C; Swern Oxidation; 0.25 h; Inert atmosphere; 2: With triethylamine in dichloromethane T=-50 - 20°C;