Triphenylphosphine → HCID 154041574, compound

Participants

Reaction Steps

(1R, 2S, 5R-)-(-)-Menthol (7.3 g, 45 mmol) and triphenylphosphine (8.65 g, 33 mmol) in dry tetrahydrofuran under argon were cooled in an ice bath and diethyl azodicarboxylate (5.2 ml, 5.7 g, 33 mmol) in dry tetrahydrofuran (30 ml) was added dropwise over 15 minutes. The ice bath was removed and ethyl 2-hydroxyimino-3-oxobutyrate (4.77 g, 33 mmol) in dry tetrahydrofuran (30 ml) was added dropwise over 20 min. The mixture was stirred at room temperature for 18 h and then warmed at 50° C. for 1.5 h. The mixture was cooled and the tetrahydrofuran was removed by evaporation in vacuo. Toluene was added to the residue and evaporated in vacuo. The residual yellow oil was chromatographed on silica gel, eluting with carbon tetrachloride, followed by hexane, followed by hexane/ethyl acetate mixtures. After evaporation of relevant fractions the title compound was obtained as an oil, νmax (CH2Cl2) 2945, 2920, 2860, 1740, 1685, 1365, 1315, 1235, 1070 and 1005 cm-1 ; δ (250 MHz, CDCl3) 0.87 (3H, d, J 7.3 Hz), 0.90 (3H, d, J 6.8 Hz), 0.92 (3H, d, J 6.3 Hz), 0.95-1.14 (2H, m), 1.14-1.35 (1H, m), 1.32 (3H, t, J 7.2 Hz), 1.49-1.63 (2H, m), 1.63-1.80 (2H, m), 2.13 (1H, m), 2.40 (3H, s), 4.34 (2H, q, J 7.1 Hz), 4.70 (1H, broad s).

Provenance & Evidence