Naturally occurring dibenzofurans. Part 5. Synthesis of melacarpic acid
Abstract
The total synthesis of the lichen dibenzofuran melacarpic acid (5)[1-heptyl-3-hydroxy-7-methoxy-9-methyldibenzofuran-2-carboxylic acid] was achieved by intramolecular Ullmann coupling of methyl 5-bromo-4-(2-bromo-5-methoxy-3-methylphenoxy)-6-heptyl-2-methoxybenzoate (48) or methyl 6-heptyl-5-iodo-4-(2-iodo-5-methoxy-3-methyl-4-nitrophenoxy)-2-methoxybenzoate (46) followed by appropriate transformations.