Strychnine-type systems, synthesis

The latter, which is not normally isolated, may, under favorable conditions, be trapped in the presence of a strong nucleophile, as in the conversion of 340 into 338. It was surmised that the biogenetically modelled synthesis of strychnine-type systems was a demonstration of such a reaction. 

The acid-catalyzed conversion of the l,2,3,4-tetrahydro-j8-carboline derivative 337 (R = CHg) into the strychnine-type ring system 338 has been attributed to an equilibrium involving the protonated Schiff s base 339 of tryptamine (i.e., the intermediate in the Pictet-Spengler type synthesis of tetrahydro-j8-carbolines, cf. Section III, A, 1, a), and the a- (337) and the j8-condensation products (340). 

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