Ethanol → Ethyl [(3S)-7-chloro-3,4-dihydro-2H-1,4-benzoxazin-3-yl]acetate

Temperature

60 °C

Zinc trifluoromethanesulfonate (2.87 g, 7.91 mmol) was added to a well-stirred solution of (2E or Z)-(7-chloro-2H-1,4-benzoxazin-3(4H)-ylidene)acetate (Intermediate 19, 20 g, 79.1 mmol) in EtOH (150 mL, HPLC grade) at 20° C. The resulting mixture was evacuated and purged with N2 for several times, then (+)-1,2-bis(2s, 5s)-2,5-diphenylphospholanol ethane(1,5-cyclooctadiene) rhodium(I)tetrafluoroborate (0.51 g, 0.63 mmol) was added at 20° C. The resulting solution was evacuated and purged with N2 for several times again. Then the reaction was stirred at 60° C. for 16 h under H2 (15 bar pressure). The mixture was concentrated. The crude product was purified by silica gel column chromatography with EtOAc in PE from 0 to 20%. The pure product fraction was concentrated. This resulted in the title compound (18.9 g, 93.6%) as an orange oil.

1. customThe resulting mixture was evacuated
2. custompurged with N2 for several times
3. customThe resulting solution was evacuated
4. custompurged with N2 for several times again
5. concentrationThe mixture was concentrated
6. customThe crude product was purified by silica gel column chromatography with EtOAc in PE from 0 to 20%
7. concentrationThe pure product fraction was concentrated

ORD record

ord-bb18b98465024966913916052576abfa

Source dataset

uspto-grants-2016_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09394291B2