Starting from tryptamine and dimeric piperidine derivative 8, the synthesis of 4, an immediate precursor in the biosynthesis of the Nitraria alkaloids, was accomplished. Cyclization of this achiral intermediate in aqueous solution produced a mixture of natural nitramidine 17 and one of its stereoisomers. Stereoselective reductions of these iminium salts with several reductors produced nitrarine (1), isonitrarine (2), and two new isomeric Nitraria indole alkaloids.