Total synthesis of (-)-(α)-kainic acid via a diastereoselective intramolecular [3 + 2] cycloaddition reaction of an aryl cyclopropyl ketone with an alkyne

Article abstract of DOI:10.1021/ol3008414

An enantioselective synthesis of (-)-(α)-kainic acid in 15 steps with an overall yield of 24% is reported. The pyrrolidine kainoid precursor with the required C2/C3 trans stereochemistry was prepared with complete diastereoselectivity via an unprecedented SmI₂-catalyzed intramolecular [3 + 2] cycloaddition reaction of an aryl cyclopropyl ketone and an alkyne. Double bond isomerization was then employed to set the remaining stereochemistry at the C4 position en route to (-)-(α)-kainic acid.