6-O-Methylarthothelin and 1,3,6-Tri-O-Methylarthothelin, Two New Xanthones From a Dimelaena Lichen

Abstract

6-O-Methylarthothelin (5) (2,4,5-trichloro-1,3-dihydroxy-6-methoxy-8- methyl-9H-xanthen-9-one) and 1,3,6-tri-O-methylarthothelin (7) (2,4,5- trichloro-1,3,6-trimethoxy-8-methyl-9H-xanthen-9-one) have been synthesized and shown to cooccur with norstictic acid, connorstictic acid, atranorin and 2,4,5-trichlorolichexanthone (4) in a Dimelaena lichen.