Limonoid model insect antifeedants. A stereoselective synthesis of azadiradione C, D, and E fragments through intramolecular diazo ketone cyclization

Article abstract of DOI:10.1021/jo00117a005

A stereoselective synthesis of model compound 18 of the insect antifeedant azadiradione has been accomplished starting from α-cyclocitral in 12 steps in 15% overall yield. The strategy for the synthesis is based on an intramolecular cyclopropanation of a diazo ketone and subsequent selective cleavage of a cyclopropyl ketone. Reactivity differences in the cleavage of the key cyclopropyl ketone 13 and its homolog 12 lacking the furyl ring are explored.