Ammonium formate → 5-tert-Butyloxycarbonylamino-2-amino-3-hydroxy-1,6-diphenylhexane, (2S,3S,5S)-

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Reaction Steps

A solution of the product from Example 19C (150 gm, 250 mmol) dissolved in absolute EtOH (2 liters) was treated with 10% Pd/C (18 gm, pre-wetted), followed by addition of ammonium formate (78.6 gms, 1.25 moles) dissolved in H2O (200 ml). The resulting mixture was stirred at reflux for 2.5 hours. The mixture was cooled to room temperature and filtered through a pad of infusorial earth (20 g). The filter cake was washed 3 times with EtOH (70 ml each). The filtrate was concentrated in vacuo. The residue was dissolved into EtOAc (1L) and washed (1N NaOH, followed by H2O, followed by brine), dried (Na2SO4), filtered and concentrated in vacuo. to a constant weight of 95 gms. (99.2 % of theory). The light yellow solid (91.5 gm of the 95 gm) was slurried in hot heptane (600 ml) (steam bath) and treated with isopropanol (45 ml), and swirled to effect solution. The solution was allowed to slowly cool to room temperature over 3 hours, kept at room temperature for 2 more hours and filtered. The filter cake was washed 10 times with 9/1 hexane-isopropanol (30 ml each) to give the desired product as an off-white finely crystalline solid which was dried to constant weight of 57.5 gm.

Provenance & Evidence