The structure of connorstictic acid. A depsidone from the lichen Lecidea aspidula

Abstract

Connorstictic acid (2) was isolated from the lichen Lecidea aspidula as the corresponding tetraacetate(3). The structure of the latter compound was confirmed by synthesis in several steps from the known depsidone, norstictic acid (4). Direct reduction of norstictic acid with sodium triacetoxyborohydride led to the formation of connorstictic acid.