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Paper | Regular issue | Vol 41, No. 2, 1995, pp.353-362
Published online, 1st January, 1970
DOI: 10.3987/COM-94-6960
Transformation of Na-Boc-tetrahydroalstonine to Na-Boc-5β-cyanotetrahydroalstonine, Na-Boc-21α-cyanotetrahydroalstonine, and Na-Boc-3,14-didehydrotetrahydroalstonine

Minna Halonen, Reija Jokela, and Mauri Lounasmaa*

*Laboratory for Organic and Bioorganic Chemistry, Technical University of Helsinki, FIN-02150 Espoo, Finland

Abstract

Tetrahydroalstonine (1) was transformed to its Na-Boc-derivative (4), which was then oxidized to the corresponding cis-Nb-oxide (5a). The modified Polonovski reaction of the cis-Nb-oxide (5a), followed by KCN treatment, led to Na-Boc-5β-cyanotetrahydroalstonine (7), Na-Boc-21α-cyanotetrahydroalstonine (8a), and Na-Boc-3,14-didehydrotetrahydroalstonine (9), of which the first (7) is a good model for the naturally occurring 5β-carboxytetrahydroalstonine (2b) and the second (8a) the chemical equivalent of Na-Boc-20,21-didehydro-tetrahydroalstonine (Na-Boc-cathenamine) (8b).