1: H(+) / CH2Cl2 2: sodium borhydride / ethanol 3: 2.) H(+) / 1.) pyridine; 2.) MeOH 4: sodium azide / dimethylformamide View Scheme

sodium hydride 1) THF/DMSO, 0 deg C, 10 min; 2) THF/DMSO, r.t., 16 h; Yield given. Multistep reaction. Yields of byproduct given;