Sulfuric Acid → Isoxanthohumol

Participants

Reaction Steps

To the suspension of the O'Donnell phase transfer catalyst O-allyl-N-(9-anthracenylmethyl)cinchonidinium bromide (34 mg, 0.056 mmol) in 1 ml of toluene is added xanthohumol (2 OH groups protected) (in part TIPS-protected: 37 mg, 0.056 mmol) in 1 ml of toluene. Subsequently, 0.5 ml of 25% NaOH is added and the mixture is stirred for 24 h at room temperature. For workup, 20 ml of H2O and 20 ml of ethyl acetate are added. The aqueous phase is acidified with H2SO4 and extracted twice with ethyl acetate. The organic phase is washed with NH4Cl solution and H2O, dried and eluted through a silica gel column using CHCl3/methanol. Removal of protection proceeds in a manner known from the literature.

Provenance & Evidence