Reaction Steps
A 2 liter 3 neck flask equipped with a Dean-Stark trap, condenser, thermometer, mechanical agitator, and nitrogen inlet and outlet was charged with 392.5 g of 2,2,3-trimethylcyclopent-3-en-1-yl acetaldehyde at a purity of 88.9% (2.30 moles), 415 g of 2-methyl-2-propen-1-ol (5.64 moles), 0.2 g of p-TSA and 1 liter of heptane. The contents were brought to reflux and 43 ml of water were collected. The batch was cooled and washed with 2×250 ml of 10% sodium hydroxide. The batch was dried (MgSO4), filtered and concentrated in vacuo to yield 671 g of crude 2,2,3-trimethylcyclopent-3-en-1-yl acetaldehyde bis-(2-methyl-2-propenyl) acetal. BP 88° C./1.0 mmHg; 1H-NMR (300 MHz), δ 0.76 (3H, s), 0.98 (3H, s), 1.58 (1H, m), 1.61 (3H, s), 1.76 (6H, s), 1.86-2.0 (3H, m), 2.31 (1H, br s), 3.88-4.04 (4H, m), 4.65 (1H, m), 4.87 (2H, s), 4.89 (2H, s), 5.22 (1H, s); 13C-NMR (75 MHz), δ 12.74, 19.87, 19.91, 25.71, 33.98, 35.88, 46.20, 47.10, 69.00, 69.72, 102.28, 112.27, 112.35, 122.36, 142.84, 148.98; IR (Neat), 1130, 1000 cm-1 ; MS (m/e), 206 (M+ -72), 108 (Base); The crude acetal, with 3 g of citric acid added, was distilled through a 10" saddle packed column at a pressure of 115 mmHg. A total of 185.6 g of lights was distilled out between 68°-115° C. The batch was now heated under nitrogen at 160° C. for 3 hours. The batch was now distilled to afford 320.1 g of purified product (74% yield). BP 81° C./0.4 mmHg; 1H-NMR (300 MHz), δ 0.88 (3H, s), 0.96 (3H, s), 1.59 (3H, s), 1.71 (3H, s), 1.9-2.4 (5H, m), 2.65 (1H, m), 4.71 (1H, s), 4.76 (1H, s), 5.24 (1H, s), 9.49 (1H, d, J=5.43 Hz); 13C-NMR (75 MHz), δ 12.64, 20.26, 22.67, 26.34, 34.19, 37.57, 47.24, 50.47, 52.29, 113.20, 121.39, 143.01, 149.47, 205.82; IR (Neat), 3080, 3050, 2950, 2715, 1730, 1655 cm-1 ; MS (m/e), 206 (M+), 108 (Base);
