Stereocontrolled Synthesis and Activity of multi-oxygenated Marine Natural Products

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Some marine natural products have been taken as sea foods, which occasionally contaminate some natural products affecting human higeen. The corresponding studies have been done from the point of molecular sciences. Those marine natural products are represented by tetrodotoxin (TTX) and ciguatoxin (CTX). First of all, the first example TTX and its analogs were extracted from pupper fish lever, and the mother liquor from crystallization of TTX afforded various analogs, which were determined by a hybrid type nano-LC-ESI-Q-TOF-MS analyzer with an ion-exchange column developed with aqueous media as well as deuterium oxide for comparison. About twenty peaks were assigned to be the analogs of TTX from the LC-MS with deutrium exchange, that technology affords the clear number of exchangeable protons on oxygen or nitrogen atoms of TTX analogs. On the other hand, two deoxy analogs were synthesized during the period of this grant ; thus, 5,11-dideoxy TTX and 11- deoxy TTX.Attempted total synthesis toward another natural product CTX was partly successful to conclude the synthesis of the left hand portion of CTX as well as 80% of the right hand portion of CTX molecules. The method includes the original synehtic methodology and concept from the Isobe's research group ; thus, sugar actylene, biscobalthexacarbonyl complex of the acetylenes, acidic cyclization employment of these complex, conversion of the cyclized complex into vinyl silanes, and judicious repeat of these methods for further ether ring cyclization. The coupling of these right and left segments is remained, but mostly the initial plan has been achieved. The post synthesis project have already been set up eith protein system which is promising to be applicable to the TTX, CTX class of marine compounds.