Di-tert-butyl dicarbonate → tert-butyl ((3aR,5R,6R,7R,7aR)-6-(benzyloxy)-7-fluoro-5-(1-hydroxyethyl)-5,6,7,7a-tetrahydro-3aH-pyrano[3,2-d]thiazol-2-yl)(methyl)carbamate

Participants

Reaction Steps

To a solution of tert-butyl ((3aR,5S,6R,7R,7aR)-6-(benzyloxy)-7-fluoro-5-formyl-5,6,7,7a-tetrahydro-3aH-pyrano[3,2-d]thiazol-2-yl)(methyl)carbamate (0.930 g, 2.19 mmol) in anhydrous THF (15 mL), at 0° C. and under N2, was added MeMgBr (1.4 M in THF/toluene, 3.0 mL, 5.2 mmol). After addition the mixture was stirred at room temperature for 3 h. The reaction was quenched with saturated aqueous NaHCO3 solution (30 mL), and then extracted with EtOAc (3×30 mL). The combined extract was dried over anhydrous Na2SO4. After filtration the solvent was evaporated under reduced pressure, and the residue was dissolved in DCM (40 mL) and Boc2O (2.0 g, 9.2 mmol) was added. The mixture was stirred at room temperature for 16 h. After concentration the residue was purified on silica gel by automatic flash column chromatography (EtOAc/hexanes, 1:10 to 1:2), affording tert-butyl ((3aR,5R,6R,7R,7aR)-6-(benzyloxy)-7-fluoro-5-(1-hydroxyethyl)-5,6,7,7a-tetrahydro-3aH-pyrano[3,2-d]thiazol-2-yl)(methyl)carbamate as an off-white foam (0.767 g, 80%), which contained two diastereomers.

Provenance & Evidence