Transformation of Azadiradione to Nimbocinol and 17β‐Hydroxynimbocinol, and StructurePesticidal‐Activity Relationship of Triterpenoids isolated from Azadirachta indica A. Juss. (Neem)

During studies on the structurepesticidal‐activity relationship of Azadirachta indica constituents, azadiradione (1) was treated with methanolic K2CO3 to obtain 7‐deacetyl derivative nimbocinol (2). Unexpectedly, 17β‐hydroxynimbocinol (3), reported earlier as a natural product, was also formed. The structurepesticidal‐activity relationship of triterpenoids 1–16 against Anopheles stephensi Liston is described towards understanding the active functionalities responsible for the pesticidal activity of triterpenoids having apoeuphane(apotirucallane) and gedunin skeleta. The pesticidal activities of triterpenoids 2–8 are reported for the first time.