3,4-dihydro-2H-pyran → HCID 57815104, compound

Participants

Reaction Steps

The (2R,3S)-2-hydroxy-3-{[3-[methyl(methylsulfonyl)amino]-5-({[(1R)-1-phenylethyl]amino}carbonyl)benzoyl]amino}-4-phenylbutanoic acid methylester obtained in Reference Example 25 2.30 g (4.06 mmol) was dissolved in tetrahydrofuran 8 mL and thereto were added 3,4-dihydro-2H-pyrane 4.80 mL and p-toluenesulfonic acid pyridinium 204 mg (0.81 mmol) and the mixture was stirred under reflux for 8 hours. After distillating tetrahydrofuran off, the residue was extracted by adding ethyl acetate and 5% aqueous sodium carbonate solution. The organic layer was washed with an aqueous saturated sodium chloride solution and dried on magnesium sulfate, filtered and concentrated. The concentrated residue was purified by a column chromatography on silica gel (eluted with chloroform-methanol system) and recrystallized from a mixed solvent of ethyl acetate and hexane. A precipitated material was collected by filtering and dried to give 1.81 g (2.78 mmol) of the title compound (yield: 69%).

Provenance & Evidence