Gephyrotoxin absolute configuration

Fig. 13. Two different conformations for as- decahydroquinoline with the same absolute configuration (a) as in gephyrotoxin, Fig. 12, and (b) as in pumi 10 oxin C, Fig. iq -phe numbering coincides with the numbering in the respective molecules. 

Fig. 14. Structure of gephyrotoxin. The absolute configuration is based on x-ray analysis of hydrobromide and is depicted on the right (86). The natural compound is the 1-enantiomer (107). It is, therefore, inexplicable that synthesis from L-pyroglutamic acid (107) of the enantiomeric configuration revealed by x-ray analysis should yield the d-enantiomer. Fujimoto and Kism (107) proposed that the true configuration of natural gephyrotoxin must be opposite to that revealed by x-ray analysis. The x-ray analysis was done on gephyrotoxin isolated from the same population of frogs as the material shown by optical rotation measurements to be the levorotatory enantiomer. However, the two samples of gephyrotoxin were from extracts obtained in different years...

Fig. 17. Structure of gephyrotoxin 223AB. The absolute configuration is unknown, but is arbitrarily depicted so that the absolute configuration at C-5 corresponds to C-2 of pumiliotoxin C which also has a n-propyl substituent...

Fig. 27. Possible biosynthetic pathways from a 2,6-disubstituted piperidine to various dendrobatid alkaloids. The absolute configuration suggested for the precursor of gephyrotoxin 223AB is arbitrary. The absolute configuration of gephyrotoxin is based on x-ray...

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