Synthesis of virgatol and virgatenol, two naturally occurring coumarins from Pterocaulon virgatum (L.) DC, and 7-(2,3-epoxy-3-methylbutoxy)-6-methoxycoumarin, isolated from Conyza obscura DC

摘要

yThe synthesis of a number of naturally occurring coumarins from Pterocaulon virgatum (L.) and Conyza obscura DC is described for the first time. It concerns the synthesis of 7-(2-hydroxy-3-methoxy-3-methylbutoxy)-6-methoxycoumarin (virgatol, 1), 7-(2-hydroxy-3-methyl-3-butenyloxy)-6-methoxycoumarin (virgatenol, 2) and 7-(2,3-epoxy-3-methylbutoxy)-6-methoxycoumarin (3). In addition, a straightforward synthesis of scopoletin (4) (7-hydroxy-6-methoxycoumarin) is reported and the synthesis of a new coumarin derivative, 6-methoxy-7-(2-oxo-3-methylbutoxy)coumarin (7), is described.