Chemie und Stereochemie der Iridoide, XVI. EPC‐Synthese von (−)‐Hypnophilin

Chemistry and Stereochemistry of Iridoids, XVI. – EPC‐Synthesis of (−)‐Hypnophilin The synthesis of enantiomerically pure (−)‐hypnophilin (27) from (6R,7R)‐(−)‐7‐hydroxy‐3‐oxabicyclo[4.3.0]non‐1‐en‐9‐one (1) is described. 1 was obtained in 93% yield from catalpol, which is readily available from the aqueous sodium carbonate extract of Picrorhiza kurrooa (Scrophulariaceae). The specific rotation, MS, 1H‐ and 13C‐NMR data of synthetic (−)‐hypnophilin were identical with those of the natural product.