The Identification and Synthesis of Two New β-Orcinol para-Depsides in the Lichen Pseudocyphellaria norvegica

Abstract

The new lichen depsides, 2′-O-methylnorbarbatic acid (9) and 2′-O-methylnorobtusatic acid (12) have been detected in Pseudocyphellaria norvegica and the structures confirmed by total synthesis. In addition, the known depsides 4-O-demethylbarbatic acid (3), barbatic acid (4), diffractaic acid (5), 4-O-demethyldiffractaic acid (6), methyl 4-O-demethylbarbatate (7), methyl barbatate (8) and norobtusatic acid (II) were shown in this lichen species.