Allyl bromide → 2-Phenyl-2-methyl-4-pentenoyl cyclohexane

Participants

Reaction Steps

A solution of 31.39 g (0.2797 mol) of t-BuOK in 100 mL of THF was added dropwise to a solution of 55.00 g (0.2543 mol) of cyclohexyl 1-phenylethyl ketone and 26.4 mL (0.3052 mol) of allyl bromide in 136 mL of THF (cooled in a wet ice acetone bath). THF washings (16 mL) were added to the reaction mixture. The cooling bath was removed after addition. After reaction completion (2 h), the reaction mixture was quenched with 300 mL of 1 N HCl (pH=0) and extracted with 300 mL of heptane. The heptane extract was washed with 10% NaHCO3 (aq) (pH=9), dried over MgSO4, gravity filtered and concentrated under vacuum to afford 59.70 g (91.58%) of title compound as an amber oil: 1H NMR (d6-DMSO): δ 7.32-7.42 (m, 2H, phenyl CH), 7.24-7.31 (m, 3H, phenyl CH), 5.34-5.47 (m, 1H, —CH═CH2), 5.02 (dd, J=17.1 Hz, J=2.1 Hz, 1H, —CH═CH—H (trans)), 4.97 (ddd, J=10.2 Hz, J=2.2 Hz, J=1.0 Hz, 1H, —CH═CH—H (cis, W-coupling)), 2.66 (ddd, J=14.2 Hz, J=6.9 Hz, J=1.0 Hz, 1H, —CH2CH═CH2), 2.59 (ddd, J=14.2 Hz, J=7.3 Hz, J=1.0 Hz, 1H, —CH2CH═CH2), 2.38-2.49 (m, 1H, cyclohexyl CH), 1.48-1.69 (m, 4H, cyclohexyl —CH2), 1.46 (s, 3H, —CH(CH3 )ph), 1.36-1.44 (m, 1H, cyclohexyl —CH2), 0.82-1.36 (m, 5H, cyclohexyl —CH2).

Provenance & Evidence