Trifluoroacetic anhydride → HCID 66876350, compound

Participants

Reaction Steps

Under a nitrogen atmosphere, NaBH4 (69.6 mg, 1.84 mmol) was added to a methanol (10 ml) solution of the methyl (1R,5S)-8-benzyl-3-oxo-8-azabicyclo[3.2.1]octane-2-carboxylate ((−)-2b) (264 mg, 0.92 mmol) obtained in Example 19, in an ice bath, and the reaction mixture was stirred for 2 hours. After completion of the reaction, a saturated aqueous ammonium chloride solution was added to the reaction mixture and the excess solvent was evapolated under reduced pressure. The residue was adjusted to pH 8.0-8.5 with a saturated aqueous sodium hydrogencarbonate solution and extracted with chloroform. The extract was dried over Na2SO4, filtered and then concentrated in vacuo. Then, the residue was dissolved in chloroform (10 ml) under a nitrogen atmosphere, and triethylamine (267 μl, 1.91 mmol) and DMAP as a catalyst were added thereto. In an ice bath, trifluoroacetic anhydride (203 μl, 1.44 mmol) was added thereto and the resulting mixture was stirred at room temperature for 44 hours. After completion of the reaction, the reaction mixture was adjusted to pH 8.0-8.5 with a saturated aqueous sodium hydrogencarbonate solution and extracted with chloroform. The extract was dried over Na2SO4, filtered and then concentrated in vacuo, and the thus obtained crude product was purified by a silica gel column chromatography (AcOEt:hexane=1:5) to obtain 192.2 mg of the title compound methyl (1R,5S)-8-benzyl-8-azabicyclo[3.2.1]octan-2-ene-2-carboxylate. The yield from the above two steps was 81 mol %.

Provenance & Evidence