Given the structure for 5, the assignment of structure 3 to the other toxin follows directly from (a) the obvious similarity (Table I) between the'H NMR spectra of 3 and the known toxin 1 lahydroxysaxitoxin sulfate (2), 335 (b) the likewise very similar 10-carbon pattern of the respective 13C NMR spectra (50 MHz, D20), and (c) facile conversion of 3 to toxin 2, as established by TLC and'H NMR data, upon mild acid hydrolysis,(d) the shift of the ...
