A team of researchers from the University of Cambridge reports the first synthesis of azadirachtin, a secondary metabolite first isolated from Neem tree seeds. It is a highly potent insecticide that inhibits the development of the larvae of a broad spectrum of destructive insects but is harmless to mammals and beneficial insects, such as bees and ladybugs.

The structure of this complicated molecule was published in 1985, after a long, intensive research effort, but all attempts to make this compound have thus far been unsuccessful. The difficulty of the synthesis stems in part from the 16 stereocenters in the molecule, the complex pattern of oxygen-containing functional groups, and a conformation and reactivity that are strongly dependent on intramolecular bridging hydrogen bonds. The compound is highly light sensitive and can readily undergo structural rearrangement.

The key steps in making this molecule involve a "Claisen rearrangement" and a novel radical cyclization reaction. The work has been published in the journal Angewandte Chemie International Edition (doi: 10.1002/anie.200703028).

Source: EurekAlert