Limonoids from the stem bark of Cedrela odorata.

Four nomilin/obacunol derivatives and a swietenolide derivative, together with seven known limonoids, were isolated from stem bark of Cedrela odorata and their structures established by spectroscopic methods. Antifeedant activity of the isolated compounds was also tested.

Efficient short step synthesis of Corey's tamiflu intermediate.

Corey's tamiflu intermediate was synthesized from a bicyclolactam adduct obtained by base-catalyzed Diels-Alder reaction of N-nosyl-3-hydroxy-2-pyridone with ethyl acrylate. A compound that has the same array of functional groups with the Corey's intermediate was obtained in four steps from the DA adduct in 47% overall yield. The intermediate itself was also prepared efficiently by simply changing the protective group.