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Preparation of Enantiopure Non-Activated Aziridines and Synthesis of Biemamide B, D, and epiallo-Isomuscarine
Published on: June 13, 2022
Why are the terpenoid indole alkaloids of type I homochiral?
G Beke1, Patthy-Lukáts A, B Podányi
1Department of Organic Chemistry, Semmelweis University, Hogyes utca 7, Budapest, H-1092, Hungary.
Abstract:
In the presence of the enzyme strictosidine synthase, the coupling reaction of secologanin and tryptamine is completely stereoselective and affords strictosidine with 3S configuration, exclusively. The stereoselectivity is transferred and retained in most indole alkaloids of type I in which C-3 is not involved in subsequent reactions. By using results of model reactions, the stereoselectivity was interpreted by the bulkiness of the enzyme temporarily attached to the N-4 atom in the formation of the indolenine intermediate. 3S configuration is kept in the subsequent 1,2-rearrangement into the beta-carboline structure. In the formation of the oxindole derivatives, the 3S configuration is preferred, but not necessarily complete.
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