Dimethylbarbituric acid → (3R,alphaS)-t-Butyl 3-(alpha-methylbenzylamino)-4-hexenoate

Participants

Reaction Conditions

Reaction Steps

To a solution of compound (12) from Example 4 (1.080 g, 3.28 mmol) in anhydrous dichloromethane (20 ml) was added tetrakis-(triphenylphosphine)-palladium (0) (0.040 g, 1 mol %) and N,N'-dimethylbarbituric acid (0.536, 9.85 mmol). This mixture was stirred at 40° C. for 2 hours, after which the dichloromethane was removed under reduced pressure. The residue was dissolved in diethyl ether (50 ml) and washed with saturated sodium bicarbonate solution (2×20 ml) and brine (20 ml) and dried (magnesium sulphate) and the solvent was removed under reduced pressure to yield a pale yellow oil. Purification by flash chromatography on silica gel [ethyl acetate/petroleum ether (4:9)] afforded the title compound (Rf 0.30) as a colourless oil (0.950 g, 100%). δH (300 MHz; CDCl3) 7.32-7.18 (5H, m, Ph), 5.55 (1H, dq, J=15.2 and 6.4, CH3CH=CH), 5.26 (1H, ddq, J=15.2, 8.0 and 1.6, trans CH2CH=CH), 3.84 (1H, q, J=6.5, PhCHCH3), 3.45 (1H, m, NCHCH2), 2.41 (1H, dd, J=14.5 and 6.6, CH2CO2), 2.35 (1H, dd, J=14.5 and 6.5, CH2CO2), 1.65 (3H, dd, J=6.4 and 1.6, CH3C=C), 1.45 (9H, s, (CH3)3C), 1.33 (3H, d, J=6.5, PhCHCH3).

Provenance & Evidence