Chiral approach to total synthesis of phytotoxic and related nonenolides: (Z)-isomer of (6S,7R,9R)-6,7-dihydroxy-9-propylnon-4-eno-9-lactone, herbarumin-III and their C-9 epimers

A new and efficient strategy has been developed for the stereoselective total synthesis of nonenolides: (Z)-isomer of (6S,7R,9R)-6,7-dihydroxy-9-propylnon-4-eno-9-lactone, herbarumin-III and their C-9 epimers starting from d (−) ribose. The synthesis includes the coupling of the alcohol and acid fragments of the molecules, employing Yamaguchi esterification protocol followed by intramolecular ring closure metathesis. The method has efficiently constructed the 10-membered lactone skeleton of the compounds with proper stereogenic centers containing appropriate functionalities.