The synthesis of functionalized nine-membered ring lactones based on sequential esterification and ring-closing metathesis (RCM) reactions is reported. The effects of olefin substitution and allylic and homoallylic oxygenated substituents on the RCM reaction is analyzed. An unusual cyclization stereochemistry has been observed, leading to a stereoselective olefin formation in the synthesis of nonanolactones. The high selectivity can be rationalized by interaction/coordination of the homoallylic or allylic hydroxyl group with the ruthenium metal center in the ruthenacyclobutane intermediate.
ring-closing metathesis - nonanolactones - botcinolide -
Botrytis cinerea
