4-Methylmorpholine → (S)-2-tert-butoxycarbonylamino-4-(3-{3-[4-(pyridin-2-yloxymethyl)-benzyl]-isoxazol-5-yl}-pyridin-2-ylcarbamoyl)-butyric acid methyl ester

Participants

Reaction Steps

To a mixture of (S)-2-tert-butoxycarbonylamino-pentanedioic acid 5-benzyl ester 1-methyl ester (370 mg, 0.70 mmol; 66% purity) described in Manufacturing Example 2-1 and methanol (4 mL) was added palladium-carbon (40 mg, 0.19 mmol; 50% water content) at room temperature, which was stirred for 5 hours at room temperature under a hydrogen atmosphere (1 atm). The reaction mixture was replaced with nitrogen and filtered through a Celite pad. The solvent was evaporated from the filtrate under a reduced pressure, so as to obtain (S)-2-tert-butoxycarbonylamino-pentanedioic acid 1-methyl ester (300 mg) in a crude form. The crude product thus obtained was used directly in the next reaction. To a mixture of 3-(3-(4-(pyridin-2-yloxymethyl)-benzyl)-isoxazol-5-yl)-pyridin-2-ylamine (150 mg, 0.42 mmol) described in Reference Example 1 and acetonitrile (3 mL) were added (S)-2-tert-butoxycarbonylamino-pentanedioic acid 1-methyl ester (crude, 220 mg), N-methylmorpholine (46 μL, 0.42 mmol), and O-(7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyl-uronium hexafluorophosphate (180 mg, 0.46 mmol) in this order at 0° C., which was stirrer overnight at room temperature. Water was added to the reaction mixture, which was extracted with ethyl acetate. The organic layer was washed with saturated brine, and the solvent was evaporated under a reduced pressure. The residue was purified by NH silica gel column chromatography (ethyl acetate:heptane=4:1), so as to obtain the titled compound (37 mg).

Provenance & Evidence