Reaction Steps
To a solution of ((3aS,4R,5R,6R,7aS)-4,5-bis(benzyloxy)-2-oxooctahydrobenzo[d]oxazol-6-yl)methyl methanesulfonate (2.24 g, 4.86 mmol) in dry acetonitrile (12 mL) at room temperature was added a solution of tetrabutylammonium fluoride (4.933 g, 24.3 mmol) in dry acetonitrile (16 mL). The mixture was heated at reflux under N2 for 4 h. Solvent was evaporated under reduced pressure. The residue was dissolved in EtOAc (150 mL), washed with water (2×) and brine, and dried with MgSO4. The solvent was evaporated to give the crude product. This was purified by SiO2 column, eluted with 30-50% EtOAc in hexanes to give (3aS,4R,5R,6S,7aS)-4,5-bis(benzyloxy)-6-(fluoromethyl)hexahydrobenzo[d]oxazol-2(3H)-one (810 mg, 43%). MS m/z 408.1 (M+23, 100%); 1H NMR (400 MHz, CDCl3) δ 7.31-7.42 (m, 10H), 4.99 (s, 1H), 4.93 (d, J=11.7 Hz, 1H), 4.84 (d, J=11.0 Hz, 1H), 4.79 (dd, J=9.2 Hz, 3.2 Hz, 0.5H), 4.65-4.71 (m, 1.5H), 4.65 (d, J=11.1 Hz, 1H), 4.59 (d, J=11.7 Hz, 1H), 4.37 (ddd, J=47.4 Hz, 9.2 Hz, 2.3 Hz, 1H), 3.58 (t, J=6.8 Hz, 1H), 3.51 (t, J=7.8 Hz, 1H), 3.44 (t, J=8.9 Hz, 1H), 2.22 (dt, J=14.9 Hz, 2.9 Hz, 1H), 1.94-2.10 (m, 1H), 1.85-1.93 (m, 1H).
