Benzaldehyde → (4S)-3-{(2R)-2-[(S)-Hydroxy(phenyl)methyl]hex-5-ynoyl}-4-phenyl-1,3-oxazolidin-2-one

Participants

Reaction Steps

To a stirred solution of 56.8 g (221 mmol) of (4S)-3-hex-5-ynoyl-4-phenyl-1,3-oxazolidin-2-one from step A above in 265 mL of anhydrous ethyl acetate at ambient temperature under an atmosphere of nitrogen was added 6.31 g (66.2 mmol) of anhydrous magnesium chloride, 61.5 mL (442 mmol) of triethylamine, 26.9 mL (265 mmol) of benzaldehyde and 42.3 mL (331 mmol) of chlorotrimethylsilane and the resulting mixture was stirred for 72 h. The heterogeneous reaction mixture was filtered through a 300 mL plug of silica gel eluting with an additional 1 L of ethyl acetate. The filtrate was evaporated to dryness in vacuo and the residue suspended in 265 mL of methanol and 10 mL of trifluoroacetic acid. The resulting mixture was stirred at ambient temperature under nitrogen for 5 h during which time the reaction became homogeneous. All volatiles were then removed in vacuo and the residue was purified by silica gel chromatography eluting with a 5-15% ethyl acetate in hexanes gradient to afford the title compound as a white solid (65.0 g, 81.2%). 1H NMR (500 MHz, CDCl3): δ 7.30-7.28 (m, 8H), 7.09-7.07 (m, 2H), 5.42 (dd, J=8.7, 3.7 Hz, 1H), 4.76-4.72 (m, 1H), 4.72-4.67 (m, 1H), 4.65 (t, J=8.7 Hz, 1H), 4.18 (dd, J=8.7, 3.7 Hz, 1H), 3.05 (d, J=7.8 Hz, 1H), 2.24 (td, J=7.1, 2.5 Hz, 2H), 2.00-1.93 (m, 2H), 1.67-1.61 (m, 1H). LC-MS: m/z (ES) 346.1 (MH-H2O)+, 386.0 (MNa)+.

Provenance & Evidence