Biosynthesis of Lobinaline

Abstract

The biosynthesis of lobinaline (1) in intact plants of Lobelia cardinalis L. was studied by tracer methods. The incorporation data are consistent with the view that the alkaloid is formed by dimerization of α-phenacylpiperidine (3), whose piperidine nucleus is derived from lysine via a nonsymmetrical intermediate, and whose sidechain originates, as an intact C6–C2 unit, from phenylalanine via cinnamic acid.

The biosynthesis of retronecine

“…These are summarized in is likely that the erroneous results (7) have their basis in the chemistry of the degradation reactions that were employed. Ozonolysis of a Hofmann base leads to formaldehyde not only from the methylene carbon atom of the vinyl group but also from the N-methyl groups (33). It must be assumed that the apparent lack of radioactivity in the formaldehyde, derived from C-3 and C-5 by ozonolysis of Hofmann bases, was due to dilution of active formaldehyde derived from these carbons by inactive formaldehyde derived from the N-methyl groups, to yield samples whose radioactivity was beyond the limits of detection.…”