Water → 2,4-Dimethyl-2-(2,2,3-trimethylcyclopent-3-en-1-yl)-4-pentenal

Participants

Reaction Conditions

Reaction Steps

A 4 neck 2 liter round bottomed flask was charged with 600 ml of DMF and 160 g of potassium t-butoxide (1.35 moles). Under nitrogen the flask was cooled to 0° C. and 200 g of 2-(2,2,3-trimethylcyclopent-3-en-1-yl)propanal (from Example 5) at 90% purity (1.08 moles) in 100 ml of DMF were added over 40 minutes at 0°-5° C. The reaction was stirred 30 minutes at 0° C. Then 140 g of methallyl chloride (1.54 moles) in 100 ml of DMF were added dropwise over 40 minutes at 5°-15° C. The batch was stirred 30 minutes at 10°-15° C. With good stirring the reaction mixture was poured onto 1 liter of water and extracted with 3×100 ml of hexane. The hexane extract was washed with 2×500 ml of water and 1 liter of brine. The extract was dried and concentrated in vacuo. The crude mixture of C- and O-alkylates, 261.4 g, was heated in a 500 ml 3 neck flask under nitrogen at 165° C. for 6.5 hours. Fractional distillation afforded 239.5 g of purified product (86.8% yield). BP 84° C./0.15 mmHg; 1H-NMR (300 MHz), δ 0.89 (3H, s), 1.03 (3H, s), 1.11 (3H, s), 1.55 (3H, s), 1.63 (3H, s), 2.20-2.27 (4H, m), 2.53 (1H, m), 4.67 (1H, s), 4.84 (1H, s), 5.27 (1H, s), 9.79 (1H, s); 13C-NMR (75 MHz), δ 12.34, 15.27, 22.25, 24.31, 28.11, 30.89, 46.11, 48.20, 52.83, 56.17, 115.57, 120.98, 141.43, 148.00, 207.01; m (Neat), 2980, 2700, 1725, 1645, 1450, 1380, 895 cm-1 ; MS (m/e), 220 (M+), 205, 191, 121, 108 (Base), 93, 55, 41;

Provenance & Evidence