Diisopropylethylamine → tert-Butyl ((4aS,5R,7aS)-7a-(2-fluorophenyl)-3,5-dimethyl-4-oxo-3,4,4a,5,7,7a-hexahydrofuro[3,4-d]pyrimidin-2-yl)carbamate

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Reaction Steps

tert-Butyl (methylcarbamothioyl)carbamate (2.13 g, 11.2 mmol) was added to a stirred mixture of (2R,3S,4S)-methyl 4-amino-4-(2-fluorophenyl)-2-methyltetrahydrofuran-3-carboxylate (2.27 g, 9.0 mmol), N-ethyl-N-(propan-2-yl)propan-2-amine (3.9 mL, 22.4 mmol) and N-[3-(dimethylamino)propyl]-N′-ethylcarbodiimide hydrochloride (1:1) (2.15 g, 11.2 mmol) in dry DMF (18 mL) at RT under nitrogen. The mixture was stirred at RT for 3 days, then partitioned between EtOAc (50 mL) and saturated aqueous NaHCO3 (50 mL) and water (50 mL). The aqueous layer was further extracted with EtOAc (2×50 mL). The combined extracts were dried (Na2SO4), filtered and evaporated. The residue was purified by column chromatography (normal phase, 100 g, Biotage SNAP cartridge KP-Sil, 50 mL per min, gradient 10% to 25% EtOAc in n-hexane) to give the title compound (3.15 g, colourless foam). 1H NMR (400 MHz, CDCl3) δ ppm 1.51 (d, J=6.06 Hz, 3H) 1.54 (s, 9H) 3.28 (s, 3H) 3.40 (dd, J=9.09, 2.02 Hz, 1H) 4.31 (d, J=10.11 Hz, 1H) 4.36-4.45 (m, 2H) 7.10-7.24 (m, 3H) 7.33-7.40 (m, 1H) 10.53 (br. s., 1H).

Provenance & Evidence