A Single-Step Synthesis of Xyridins A and B, Metabolites from Xyris indica

摘要

A facile single-step synthesis of the title isocoumarins isolated from Xyris indica has been elaborated. Condensation of butanoyl chloride and 2-oxobutanoyl chloride with 3,4-methylenedioxyhomophthalic acid afforded xyridin A and xyridin B, respectively. Xyridin A was saponified to the corresponding keto acid, which on reduction gave the (±)-3,4-dihydro-6,7-methylenedioxy-3-propylisocoumarin in which diastereotopy of the methylenic protons around the stereogenic center was observed. A mass fragmentation mechanism for xyridins has also been suggested.