Triphenylphosphine → 4a,5,6,7,8,8a-hexahydro-4,7-dimethyl-4H-1-benzopyran

Participants

Reaction Steps

A 100 ml Hastelloy C autoclave was charged with 15 g of isopulegol, 0.09 g of chlorotristriphenylphosphinerhodium, 0.05 g of triphenylphosphine and 30 ml of dioxane. The autoclave was then charged with equal volumes of carbon monoxide and hydrogen which pressurized the autoclave to 100 kg/cm2. The reaction was carried out at a temperature of 140° C. and at a pressure of 90 to 120 kg/cm2 for a period of 5 hours. After cooling, the pressure was reduced to atmospheric, and the reaction mixture was recovered from the autoclave and distilled for purification which yielded 15.6 g of 4a,5,6,7,8,8a-hexahydro-4,7-dimethyl-4H-1-benzopyran having a boiling point of from 64° to 66° C. at 0.5 mmHg. The IR and NMR spectra of the product had the following absorption characteristics:

Provenance & Evidence