Triethylamine → (4S)-4-benzyl-3-hex-5-ynoyl-1,3-oxazolidin-2-one

Participants

Reaction Steps

To a solution of 10 g (89 mmol) of 5-hexynoic acid and 31.0 mL (223 mmol) of triethylamine in 450 mL of anhydrous tetrahydrofuran at −25° C. under an atmosphere of nitrogen was added 12 mL (98 mmol) of trimethylacetyl chloride over 20 min. Upon addition a white precipitate formed and the resulting suspension was stirred for 2 h. Next, 4.2 g (98 mmol) of anhydrous lithium chloride and 17 g (94 mmol) of (S)-(−)-4-benzyl-2-oxazolidinone were added sequentially and the mixture was allowed to gradually warm to ambient temperature over 12 h. All volatiles were removed in vacuo and the residue was diluted with water (500 mL) and extracted with ether (3×200 mL). The combined organic layers were washed with brine (100 mL), dried over magnesium sulfate, filtered and concentrated in vacuo. The crude residue was purified by silica gel chromatography eluting with a 10-25% ethyl acetate in hexanes gradient to afford the title compound as a colorless solid (22 g, 93%). 1H NMR (500 MHz, CDCl3): δ 7.35-7.31 (m, 2H), 7.28-7.25 (m, 1H), 7.19-7.21 (m, 2H), 4.69-4.64 (m, 1H), 4.22-4.15 (m, 2H), 3.28 (dd, J=13.4, 3.3 Hz, 1H), 3.13-3.01 (m, 2H), 2.78 (dd, J=13.4, 9.6 Hz, 1H), 2.34-2.30 (m, 2H), 1.99 (t, J=2.7 Hz, 1H), 1.96-1.88 (m, 2H). LC-MS: m/z (ES) 272.2 (MH)+, 294.3 (MNa)+.

Provenance & Evidence