Acetic Acid → HCID 123898871, compound

To a 500 mL flask was added (1RS,3S,4S)-4-((tert-butyldimethylsilyl)oxy)-1-(5-(2,5-dimethyl-1H-pyrrol-1-yl)pyrazin-2-yl)-3-fluorocyclohexanecarboxylic acid (46 g), toluene (250 mL) and HOAc (0.8 g, 13.3 mmol) under nitrogen. The reaction mixture was refluxed for 1 hour and then cooled to room temperature before adding 6% aqueous NaHCO3 (200 mL). The phases were separated and the aqueous layer was extracted with heptane (250 mL). The combined organic layer was washed with 10% brine (200 mL) and concentrated under reduced pressure (50±5° C., 50˜100 mbar) to give an oil. After the addition of 80 mL methanol to the residue, the mixture was heated to 55±5° C. and stirred for 1 hour. The temperature was cooled to 25±5° C. over a 2 hour period and stirred for a further 2-3 hours. The resulting suspension was filtered and the wet cake was dried under reduced pressure (50±5° C., 50˜100 mbar) for 3 hours to give 8.6 g of 2-((1S,3S,4S)-4-((tert-butyldimethylsilyl)oxy)-3-fluorocyclohexyl)-5-(2,5-dimethyl-1H-pyrrol-1-yl)pyrazine as a crystalline solid (dr>99:1). The mother liquor was concentrated under reduced pressure (50±5° C., 50˜100 mbar) to give 34.5 g (71 mmol) dark oil. To this residue was added tBuOH (200 mL), followed by tBuOK (8.0 g, 71 mmol). The reaction mixture was heated to 90±5° C. and stirred for 3 hours. After the temperature was cooled to room temperature, 10% aqueous NaHCO3 (150 mL) was added followed by heptane (200 mL) and the mixture was stirred for a further 10 minutes. The phases were separated and the aqueous layer was washed with heptane (200 mL). The combined organic layers were washed with 10% brine (150 mL) and concentrated under reduced pressure (50±5° C., 50˜100 mbar) to give an oil residue. To this residue was added methanol (60 mL), and the mixture was heated to 55±5° C. After stirring for 1 hour, the temperature was cooled to 25±5° C. over a 2 hour period followed by stirring for a further 2 hours. The suspension was filtered and the resulting wet cake was dried under reduced pressure (50±5° C., 50-100 mbar) for 3 hours to give the second batch of 2-((1S,3S,4S)-4-((tert-butyldimethylsilyl)oxy)-3-fluorocyclohexyl)-5-(2,5-dimethyl-1H-pyrrol-1-yl)pyrazine as a crystalline solid (5.6 g, dr=98:2). The overall yield of the 4 steps starting from 2-bromo-5-(2,5-dimethyl-1H-pyrrol-1-yl)pyrazine is 51.8%. mp=100.6° C.˜102.9° C. LC/MS: [M+H]+=404.2459, 1H NMR (400 MHz, DMSO-d6): 8.53 (s, 1H), 8.50 (s, 1H), 5.75 (s, 2H), 4.25˜4.43 (m, 1H), 3.60˜3.69 (m, 1H), 3.25 (s, 6H), 2.93˜3.00 (m, 1H), 2.19˜2.27 (m, 1H), 1.98 (s, 6H), 1.72˜1.90 (m, 3H), 1.39˜1.61 (m, 2H), 0.80 (s, 9H), 0.01 (d, J=4 Hz, 6H)., HPLC (Instrument: Agilent Technologies 1200 series. Column: Waters Xbridge C18, 150*3.0 mm, 3 um. Column temperature: 35° C. Flow rate: 0.70 mL/min. Detection: 210 nm/DAD. Mobile phase composition: A: 0.1% H3PO4 in water; B: acetonitrile. Gradient: 0 min: 90% A, 10% B; 5 min: 100% B; 11 min 100% B) retention time: 8.084 min for 2-((1S,3S,4S)-4-((tert-butyldimethylsilyl)oxy)-3-fluorocyclohexyl)-5-(2,5-dimethyl-1H-pyrrol-1-yl)pyrazine, 8.324 min for 2-((1R,3S,4S)-4-((tert-butyldimethylsilyl)oxy)-3-fluorocyclohexyl)-5-(2,5-dimethyl-1H-pyrrol-1-yl)pyrazine.

1. temperatureThe reaction mixture was refluxed for 1 hour
2. customThe phases were separated
3. extractionthe aqueous layer was extracted with heptane (250 mL)
4. washThe combined organic layer was washed with 10% brine (200 mL)
5. concentrationconcentrated under reduced pressure (50±5° C., 50˜100 mbar)
6. customto give an oil
7. temperaturethe mixture was heated to 55±5° C.
8. temperatureThe temperature was cooled to 25±5° C. over a 2 hour period
9. stirringstirred for a further 2-3 hours
10. filtrationThe resulting suspension was filtered
11. customthe wet cake was dried under reduced pressure (50±5° C., 50˜100 mbar) for 3 hours

ORD record

ord-6f56ed4a01ec4879bca1f59713757afa

Source dataset

uspto-grants-2016_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09242996B2