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Abstract

All the experimental evidence is consistent with the 1-methyl-A 1-pyrrolinium salt (30) being a precursor of the tropane nucleus. The various biosynthetic routes which have been established for its formation are summarized in Fig. 4. Initially it was thought that the double bond in the iminium salt could isomerize between its C-2 and C-5 positions, which would result in the scrambling of any isotopic label (e.g. 14C