1: 1.) dibutyltin oxide, 2.) Et3N / 1.) MeOH, reflux, 2 h, 2.) 15 min 2: 94 percent / lithium triethylborohydride / dimethylsulfoxide; tetrahydrofuran 3: 47 percent / pyridine / 72 h 4: 1.) pyridine, 2.) aq. acetic acid / 1.) 2 d, 2.) 80 deg C, 30 min 5: 85 percent / LiN3 / dimethylformamide / 2 h / 100 °C View Scheme

trimethylsilyl trifluoromethanesulfonate; ammonia; water; bis(trimethyl-silyl)acetamide 1.) acetonitrile, reflux, 2.5 h, 2.) MeOH, 80 deg C, 18 h; Yield given. Multistep reaction. Yields of byproduct given;