Reduction products from cis- and trans-isocohumulone

Abstract

The preparations of cis- and trans-tetrahydroisocohumulone, (IV) and (V), cis- and trans-neohydroisocohumulone, (VI) and (VII), and cis- and trans-ρ-tetrahydroisocohumulone, (IX) and (X), from colupulone are described. Reduction of trans-tetrahydroisocohumlone (V) with hydrogen over palladised charcoal gives, in addition to (VII), 4-hydroxy-2-isobutyryl-4-isohexanoyl-5-isopentylcyclopentan-1-one (VIII). Reduction of cis-tetrahydroisocohumulone (IV) with sodium borohydride gives 3,4-dihydroxy-4-(1-hydroxy-4-methylpentyl)-2-isobutyl-5-isopentylcyclopent-2-en-1-one (XI) as well as cis-ρ-tetrahydroisocohumulone (IX).