The chemistry of terpenes. Part 23. Reaction of (+)-carane-3β,4α-diol with sulphuric acid

Abstract

Reaction of (+)-car-3-ene with hydrogen peroxide in acetic acid and alkaline hydrolysis of the product gives (+)-carane-3β,4α-diol (1) and 1-acetyl-3,3-dimethylcyclohexa-1,4-diene (4). Lengthy treatment of (1) with hot, dilute sulphuric acid gives principally p-cymene (7) and (±)-carvenone (8). Shorter treatment of the diol (1) with acid gives (–)-2-endo-hydroxy-4-isopropyl-1-methyl-7-oxabicyclo[2.2.1]heptane (10), (–)-2-exo-hydroxy-2,6,6-trimethyl-7-oxabicyclo[3.2.1]octane (11), (–)-2-exo-hydroxy-1,6,6-trimethyl-7-oxabicyclo[3.2.1]octane (12), (–)-p-menth-4-ene-trans-1,2-diol (13), and (+)-p-menth-4(8)-ene-trans-1,2-diol (14).