Synthetic routes for tryptamines

The key steps in practical routes to eseroline derivatives depend in the end on cyclization of a substituted 3- -aminoethyloxindole (p. 35). 

The BC rings of physostigmine are probably cis fused (cf. chimon-anthine, p. 46) since treatment of eserethole methine with acid regenerated eserethole methiodide this means that the solution to the absolute stereochemistry will be given once the configuration of any one of the asymmetric atoms is known. 

The Harmala Bases. Harmine (the main base), harmaline and harmalol, along with the quinazoline, vasicine, make up about 2-3% of the seeds of the rutaceous plant, Peganum harmala. These bases are also found in eight other families which include the Leguminosae, Rubiaceae and Passifloraceae. 

In Chart 4.2 are sketched some of the reactions whose interpretation lead to the deduction of the structures of the three bases. The work was not as simple as it is made to appear and for example the nature of the base (harman) which was originally produced by oxidation of tryptophan with ferric chloride was obscure until the harmala alkaloids were investigated seventeen years later and the recognition of its structure was the key to this natural products problem. This pioneering work provided a solid basis for the later development of the chemistry of the yohimbines. 

Some other reactions of the harmala alkaloids are simply consequences of imine enamine tautomerism but are nevertheless important for an understanding of the chemistry of the more complex indole alkaloids (see p. 39). 

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