Gardneria Indole alkaloids

Details of the structure elucidation of gardneramine and 18-demethyl-gardneramine have now been published these and other Gardneria alkaloids figure prominently in an account of Sakai s own investigations on indole alkaloids of Japanese plants. 

Gardnerine (28), one of the major indole alkaloids of Gardneria nutans 21), was converted into koumidine (1) (22). The crucial steps in this transformation are deoxygenation from the indole ring by Pd°-assisted reduction of the aryl trifiate derivative (31) and inverting the configuration of the ethylidene side chain in 32 by Pd° catalyst (Scheme 4). 

Sakai S, Aimi N, Yamaguchi K, Yamanaka E, Haginiwa J 1982 Gardneria alkaloids. Part 13. Structure of gardmultine and demethoxygardmultine bis-type indole alkaloids of Gardneria multiflora Makino. J Chem Soc Perkin I 1257-1262... 

Plants of the G. multiflora group do not contain gardnerine (1) or its derivatives, which are characterized by their typical indole chromophore. The main constituent, gardneramine (4), and various accompanying alkaloids are all at the oxidation level of oxindole. As shown in Table HI, thirteen monomeric and two dimeric Gardneria alkaloids have been isolated, and most of the structures were elucidated through chemical correlation with the established structure of 4 165,166,169,172). 

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