1: 1.) lithium triethyl borohydride; 2.) benzyl chloroformate / 1.) THF, 6 h; 2.) ethylacetate 30 min 2: 1.) 50percent aq. trifluoroacetic acid; 2.) sodium borohydride / 1.) 30 min.; 2.) ethanol, room temp., 1 h. 3: 74 percent / hydrogen / 10percent palladium hydroxide on charcoal / ethanol / 12 h View Scheme

1: NaN3 / dimethylformamide / 12 h / 60 °C 2: 1.) sodium hydrogen telluride / 2.) pyridine 3: 81 percent / aq. trifluoroacetic acid, sodium borohydride 4: 92 percent / H2 / palladium black / acetic acid View Scheme