OXIDATION PRODUCTS OF HUMULONE AND THEIR STEREOISOMERISM

Abstract

Isomerization of tetrahydrohumulone can be accompanied by oxidation, since cis tetrahydrohumulinone is isolated from the reaction mixture. This compound can also be obtained by heat-induced isomerization of the known tetrahydrohumulinone, which is the trans form. By similar isomerization of the known humulinone, cis humulinone was prepared: this is probably an important intermediate produced from humulone during wort boiling. Trans and cis oxyhumulinic acids have been isolated for the first time. The conductivity of the boronate ester complexes of the humulinones and the oxyhumulinic acids confirms their trans or cis structures, as deduced from PMR characteristics.