Reaction Steps
A 1 liter 3 neck flask equipped with a Dean-Stark trap, mechanical agitator, condenser, thermometer and nitrogen sweep was charged with the aldehyde from Example 28, 122.9 g at approximately 90% purity (0.66 mole), 230 g of methallyl alcohol (3.20 moles), 1.0 g of p-TSA, and 500 ml of cyclohexane. The contents were refluxed for 72 hours taking off a water-methallyl alcohol distillate (18 ml). The batch was cooled, washed with 250 ml of 10% sodium carbonate and 250 ml of brine. The mixture was dried, filtered, and concentrated in vacuo to afford 311 g of a mixture of acetal, and starting material. Distillation from 2 g of soda ash afforded 119 g of starting aldehyde. The pot residue 134.8 g contains the crude acetal (IR (Neat), 2980, 1660, 1470, 1150, 1100 cm-1) which was taken up in 200 ml of tetraglyme and 3 g of citric acid. Under nitrogen the flask was heated to 185° C. and 4 ml of methallyl alcohol were collected (approximately 2.5 hours). The flask was cooled and the contents were poured into 500 ml of 10% sodium carbonate and extracted with 2×200 ml of ether. The ether was washed with 200 ml of 10% sodium carbonate, 250 ml of water, and 250 ml of brine. The batch was dried, filtered, and concentrated to afford 124.7 g of crude product. Distillation afforded 58 g of purified product (40% yield). BP 2° C./0.3 mmHg; 1H-NMR (300 MHz), δ 0.64 (3H, s), 0.78 (3H, d, J=6.78 Hz), 0.91 (3H, s), 1.05 (3H, s), 1.60 (3H, s), 1.5-1.9 (6H, m), 2.3 (2H, AB quartet, JAB =13.8 Hz), 4.63 (1H, s), 4.81 (1H, s), 9.73 (1H, s); 13C-NMR (75 MHz), δ 13.50, 14.67, 16.73, 23.34, 24.23, 27.84, 28.88, 44.24, 45.95, 46.32, 53.13, 56.56, 115.46, 141.53, 207.14; IR (Neat), 2980, 2700, 1720, 1460, 900 cm-1 ; MS (m/e), 222 (M+), 207, 166, 123, 109, 95, 41 (Base);
