Idiospermine and idiospermamine

Of the calycanthaceous alkaloids identified to date, idiospermamine is the one that is closest biogenetically to idiospermine.

Idiospermamine can be envisaged as having been formed by coupling of a calycanthine moiety (through a C ortho to a tetrahydroquinoline N, ie C8) at the beta position of the indole ring of an N-methyltryptamine molecule followed by the formation of a pyrrolidine ring through the linking of the tetrahydroquinoline N to the alpha position of the N-methyltryptamine molecule and methylation of the N of the indole ring.

Idiospermine, on the other hand, can be envisaged as having been formed by the coupling of a calycanthine moiety (through a C para to a tetrahydroquinoline N, ie C6) at the beta position of the indole ring of an N-methyltryptamine molecule followed by aryl migration of the calycanthine moiety and concerted methylation of the N of the indole ring followed by loss of H+ to effect aromatization of the indole ring (This may be regarded as analogous to the coupling in the formation of hodgkinsine and the quadrigemines which are followed by N-methylation, aryl migration and aromatization.).

I envisage the following related alkaloid might also one day be identified:

Coupling of a calycanthine moiety (through a C ortho to a tetrahydroquinoline N, ie C8) at the beta position of the indole ring of an N-methyltryptamine molecule followed by aryl migration of the calycanthine moiety and concerted methylation of the N of the indole ring followed by loss of H+ to effect aromatization of the indole ring. This alkaloid might be termed idiospermine-B.