The chemistry of terpenes. Part XII. Oxidation of (+)-car-3-ene with t-butyl chromate and photolysis of the major oxidation product, (–)-car-3-en-5-one

Abstract

Oxidation of (+)-car-3-ene (III) with t-butyl chromate affords (–)-car-3-en-5-one (I), (–)-car-3-ene-2,5-dione (IV), 8-hydroxy-m-cymene (V), and (+)-car-3-en-2-one (VI), the first in good yield. Photolysis of (–)-car-3-en-5-one (I) in ethanol yields 3-isopropyl-5-methylphenol (VII), (+)-2α,4α,6α,9α,11α,13αH-1α,5,5,8α,12,12-hexamethylpentacyclo[7,5,0,0,^2,8,0^{4, 6}, 0^{11, 13}]tetradecane-3,10-dione (X), (+)-2α,8α,10α,12αH-5β-isopropyl-1α,7α,11,11-tetramethyltetracyclo[6,5,0,0^{2, 7}, 0^{10, 12}]tridecane-3,9-dione (XIV), 4,4,7-trimethyl-cis-bicyclo-[3,2,0]hept-6-en-2-one (XVIII), and 7-anti-ethoxy-2,5,5-trimethylbicyclo[2,2,1]hept-2-en-1-ol (XIX). Acid-catalysed isomerisation of the last affords 3-endo-ethoxy-1,5,5-trimethylbicyclo[2,2,1]heptan-2-one (XXIV).