PRACTICAL SYNTHESIS OF THE PUTATIVE POLYAMINE SPIDER TOXIN FTX - A PROPOSED BLOCKER OF VOLTAGE-SENSITIVE CALCIUM CHANNELS

FTX (FTX-3.3), a putative polyamine toxin from American funnel-web spi ders, has been synthesized from tri-CBZ-L-arginine. Raney nickel media ted desulfurization of a thioamide, generated selectively with Lawesso n's reagent in the presence of the benzyloxycarbamates, allowed ready access to the S-enantiomer. The synthetic sample with the claimed stru cture for FTX-3.3 differs spectroscopically from the data published fo r the isolated toxin. The published structure requires a reappraisal o f the spectroscopic data.