Reaction of 6-hydroxy-2,3-dichloro-7-ethylnaphthazarin with KF-MeOH-[Al.sub.2][O.sub.3]. Synthesis of cristazarin, a metabolite of the lichen Cladonia cristatella

The reaction of 2-hydroxy-6-methoxy-7-chloro-3-ethylnaphthazarin with methanol activated by fluoride anion on the surface of [Al.sub.2][O.sub.3] at 120[degrees]Cgave echinochrome dimethyl ether, a metabolite of the sea urchin Scaphechinus mirabilis. Its isomer 2-hydroxy-7-methoxy-6-chloro-3-ethylnaphthazarin was converted under the same conditions into cristazarin, a metabolite of the lichen Cladonia cristatella.