Investigation of conjugate addition/intramolecular nitrone dipolar cycloadditions and their use in the synthesis of dendrobatid alkaloid precursorsNitrone dipolar cycloaddition routes to piperidines and indolizidines. Part 10. For part 9, see ref. 1.
Organic & Biomolecular Chemistry2004Vol. 2(8), pp. 1258–1258
Citations Over TimeTop 21% of 2004 papers
Helen Horsley, Andrew B. Holmes, John E. Davies, Jonathan M. Goodman, Mar�a A. Silva, Sofia I. Pascu, Ian Collins
Abstract
The sequential intramolecular conjugate addition of the oxime 13 followed by intramolecular dipolar cycloaddition of the intermediate nitrone 14 affords a mixture of the isoxazolidines 15, 16 and 17. The tricyclic 6,5,5-adduct 15 is believed to be the product of kinetic control and can be equilibrated with the epimeric tricyclic 6,5,5-isoxazolidine 17 through a beta-elimination/conjugate addition process. Conditions have been developed for the two-step conversion of the ketone 12 under thermodynamic control into the racemic tricyclic 6,6,5-adduct 16 which is the core precursor of all the known histrionicotoxin alkaloids.
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