Chemistry of hop constituents. Part 41. Tricyclodehydroisohumulone

Abstract

Tricyclodehydroisohumulone, detected as a new bittering component present in beer and in stored hops, is formed in low yield by boiling aqueous humulone in air. The new compound is best prepared (30%) by dehydrogenation of humulone with lead tetra-acetate in a slurry of acetic acid at 0 °C. Spectroscopic, mass spectrometric, and chemical studies suggest that the compound is 5-hydroxy-9,9-dimethyl-3-(3-methylbutanoyl)-10-(1-methylethenyl)tricyclo[6.3.0^1,5.0^1,8]undeca-2,4,6-trione. Evidence for the probable absolute configuration is discussed.