Sodium Fluoride → (R)-4-((R)-1-(tert-butoxy)ethyl)-3-(2,5-difluoropyrimidin-4-yl)oxazolidin-2-one

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A solution of (R)-4-((R)-1-(tert-butoxy)ethyl)oxazolidin-2-one (5 g, 26.7 mmol) in DMF (50 mL) was cooled to −5° C. under N2 atmosphere. Internal temperature was monitored and maintained at ca. −5° C. during the portionwise addition of 60% NaH (1.28 g, 32 mmol) over 5 mins (no appreciable exotherm seen, but effervescence observed and cloudy suspension resulted). Added 2,4,5-trifluoropyrimidine (3.76 g, 28 mmol) dropwise whilst still maintaining the temperature at ca. −5° C. After complete addition the reaction mixture was stirred at this temperature for 15 mins before removing the cooling bath and allowing the rm to warm to room temperature (ca. 27° C. internal temp). Left stirring at room temperature for 6 h. Sampled reaction mixture and quenched with water, extracted into EtOAc; TLC and LCMS show significant product but remaining oxazolidinone sm. Cooled reaction mixture to 0° C. and added an additional portion of trifluoropyrimidine (1.2 g, 8.95 mmol), warmed to room temperature and left stirring for 3 h at rt. Still faint residual sm seen by TLC of sample, but quenched reaction mixture at this point. Workup: [Safety Note: NaF salt present. Do not acidify workup] Quenched the reaction mixture with water (100 mL) which resulted in considerable effervescence. Added EtOAc (75 mL) and separated, extracted the aqueous with EtOAc (2×75 mL), combined the organics, washed with water (100 mL), brine (50 mL), dried (MgSO4) and concentrated to dryness to give crude product as a pale yellow oil. Crude was purified by silica gel chromatography (initial neat DCM, then ramp to 20% EtOAc/DCM). Pure product fractions were combined and concentrated to dryness to give a colourless oil which was placed under high vacuum. Upon standing the oil converted into a white solid. 1H NMR (400 MHz, CDCl3) δ 8.47 (dd, J=3, 1 Hz, 1H); 4.73-4.68 (m, 1H); 4.62-4.52 (m, 2H); 4.34-4.28 (m, 1H); 1.20 (s, 9H); 1.11 (d, 3H). MS m/z 302.1 (M+H)+.

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