This article is part of a series on Indolizidines and quinolizidines: natural products and beyond, edited by Prof Joseph P Michael, University of Witwatersrand.

Full Research Paper

Facile synthesis of two diastereomeric indolizidines corresponding to the postulated structure of alkaloid 5,9E-259B from a Bufonid toad (Melanophryniscus)

Angela Nelson¹, H Martin Garraffo², Thomas F Spande², John W Daly² and Paul J Stevenson¹

¹School of Chemistry and Chemical Engineering, Queens University, Belfast, BT9 5AG, Northern Ireland

²Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0820, USA

Beilstein Journal of Organic Chemistry 2008, 4:6doi:10.1186/1860-5397-4-6

Published:	21 January 2008

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Abstract

A short synthesis of the postulated structure for indolizidine alkaloid 259B with the hydrogens at C5 and C9 entgegen has been achieved with complete control of stereochemistry at C5. Both diastereoisomers at C8 were obtained, but neither proved to be the natural product. The comparison of the mass and FTIR spectral properties of the synthetic compounds to those of the natural material strongly suggest that the gross structure is correct and that the difference may be a branch in the C5 alkyl side-chain. The GC-retention times of the two synthetic compounds were markedly longer than that of the natural 5,9E-259B.

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