Synthesis of Side Chain Substituted 3-Butylisocoumarins and Absolute Configurations of Natural Isocoumarins from Artemisia dracunculus

A series of 3-hydroxy- and 3-bromobutyl-substituted isocoumarins was synthesized. The absolute configurations of three isocoumarin derivatives from Artemisia dracunculus, namely (−)-epoxyartemidin, (−)-2′-methoxydihydroartemidin, and (+)-3′-hydroxyartemidin were determined by chemical means via derivatization, kinetic racemate resolution (Horeau method), and comparison of the circular dichroism (CD) spectra.