Chemistry of hop constituents. Part XXXIX. A novel alkenylation reaction giving hop constituents and related compounds

Abstract

2-Acylcyclohexane-1,3,5-triones (acylphloroglucinols) can be alkenylated by bromides in the presence of ion-exchange resins to give deoxyhumulones (I), hop β-acids (II). lupones (III), and their analogues. The lupones are conveniently obtained in enhanced yields by using strongly basic resins; the deoxyhumulones are formed by using weakly basic resins. When 2-acylcyclohexane-1,3,5-triones are treated with 2-methylbut-3-en-2-ol in the presence of an acidic resin, mixtures of dihydrobenzopyrans (VII) and tetrahydrobenzodipyrans (VIII) are obtained.