1: 93 percent / lithium triethylborohydride / tetrahydrofuran; dimethylsulfoxide / Ambient temperature 2: 61 percent / Et3N, 4-dimethylaminopyridine / dimethylformamide / RT, 5 h; 4 deg C, 60 h 3: 35 percent / DAST / CH2Cl2 / 2 h / Ambient temperature 4: 72 percent / NH3 / methanol / Ambient temperature View Scheme