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Paper | Regular issue | Vol 41, No. 4, 1995, pp.807-816
Published online, 1st January, 1970
DOI: 10.3987/COM-94-7010
Total Synthesis of Na,O-Di-Boc-5β-cyano-Z-geissoschizine and Na-Boc-21α-Cyanotetrahydroalstonine, the Latter a Synthetic Equivalent of Na-Boc-Cathenamine

Mauri Lounasmaa, Minna Halonen, and Reija Jokela

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

Abstract

Modified Polonovski reaction of the synthetically prepared Na,O-di-Boc-Z-geissoschizine cis-Nb-oxide (6), followed by cyano trapping of the formed iminium intermediates, led to four compounds (1), (5a), (7), and (8a) [and to two secondary products, (9) and (10)]. The most important of these compounds were Na,O-di-Boc-5β-cyano-Z-geissoschizine (5a) and Na-Boc-21α-cyanotetrahydroalstonine (8a) [synthetic equivalent of Na-Boc-cathenamine (8b)]. Change in the reaction temperature caused one (Δ4(21)) of the intermediate iminium ions to be strongly favoured, leading to the nearly exclusive formation of compound (8a) at the expense of compounds (5a), (7), (9), and (10).