Photooxygenation of Nimonol, a Tetranortriterpenoid from Azadirachta indica. A. Juss.Author(s): Geetha Gopalakrishnan | N. D. Pradeep Singh | V. Kasinath
Journal: Molecules ISSN 1420-3049
Volume: 7; Issue: 2; Start page: 112; Date: 2002;
Keywords: Photooxygenation | tetranortriterpenoid | singlet oxygen | antifeedant
Nimonol (1), a tetranortriterpenoid isolated from the leaves of Azadirachta indica A. Juss (Meliaceae), upon photolysis undergoes both Diels-Alder and ene reactions with singlet oxygen at different sites leading to 14,15,20,21-diepoxy-23-nimonolactone (3), along with nimonolide (4), which have been well-characterised. The novelty of the reported reactions lies in hitherto unreported formation of an ÃŽÂ±-epoxide in the ring D in tetranortriterpenoids. The photoproduct 4 exhibited antifeedancy comparable to that of azadirachtin-A, the most potent antifeedant constituent isolated from neem.