dicyclohexyl-carbodiimide in ethyl acetate 3 h;

1: ethyl acetate 2: HCl / ethyl acetate; diethyl ether; H2O / 1 h / 20 °C 3: trifluoroacetic acid; molecular sieves 3 Angstroem / CH2Cl2 / 3.5 h / 20 °C 4: 90 percent / AlCl3 / CH2Cl2 / 20 °C 5: 80 percent / alane / tetrahydrofuran / 14 h / 20 °C View Scheme