BIOMIMETIC SYNTHESIS OF NITRARIA ALKALOIDS, BASED ON TETRAHYDROPYRIDINE SYNTHONS

Many of the alkaloids found in Nitraria and Lupine species can be envi saged to arise from two simple building blocks, namely, tryptamine and tetrahydropyridine. In particular in the Nitraria species, the alkalo ids occur as racemates in some cases, despite the presence of many ste reocenters. We assume that racemic alkaloids might be formed without i nterference of enzymes via spontaneous reactions of highly reactive in termediates. By carrying out a biomimetic approach many of these alkal oids were obtained by us via chemical synthesis, based on this concept of reactive precursors. The paper discusses the preparation of racemi c lupinine, spartein, and nitraramine from tryptamine and the trimer o f tetrahydropyridine, based on imine-enamine chemistry.