p-Toluenesulfonic acid → HCID 549741, compound

Participants

Reaction Steps

153 g (0.74 mole) of 2,4,4-trimethyl-3-(but-3-en-1-on-1-yl)-cyclohex-2-en-1-one (Ib) were stirred under reflux together with 135 ml of ethyl acetate and 3 g of p-toluenesulfonic acid for 2 hours. When the solution had cooled, 1,000 ml of ether were added to it, the mixture was washed with water and with saturated sodium bicarbonate solution and dried with sodium sulfate, and the solvent was distilled off under about 20 mbar. 153 g of 2,4,4-trimethyl-3-(but-2-en-1-on-1-yl)-cyclohex-2-en-1-one (Ia) were obtained, the yield being quantitative, and the product being only slightly impure according to thin-layer chromatography. Recrystallization from 500 ml of cyclohexane gave 132 g (yield: 86.8% of theory) of a product which was pure according to thin-layer chromatography; evaporating down the mother liquor gave a further 21 g (yield: 13.2% of theory) of a somewhat impure product.

Provenance & Evidence