Lupuloxinic acid

Oxidation of (co)-lupulone with alkaline peroxide gives rise to lupuloxinic acid (46 R = COOH) which is readily decarboxylated to lupulenol (46 R = H) but neither of these products has been found in hops or beer. However the related trione, dehydrolupulenol (47) has been reported to account for 15 % of the autoxidation products of the p-acids [42]. 

Treatment of lupulone or colupulone with cold alkaline hydrogen peroxide yields lupuloxinic acid (269, Fig. Ill) with molecular formula C22H32O5 (93,94). It is a... 

Fig. 111. Reaction scheme for the formation of lupuloxinic acid (269) and lupulenol (270) structural formulae of compounds 271-273.

Treatment of colupulone with cold hydrogen peroxide in strong alkali leads to a 60% yield of lupuloxinic acid, which can be decarboxylated quantitatively to lupulenol (Fig. Ill) (4). The reaction is very simple to carry out and these five-membered compounds must be more soluble in water or beer than the original colupulone. They also are probably bitter. Proper organoleptic evaluation and LC monitoring of the reaction seem worthwhile endeavours. 

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