66 (+)-ヒダントサイジン及びその立体異性体の合成(ポスター発表の部)

概要

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A naturally occurring spiro-sugar, (+)-hydantocidin 1, possesses a strong herbicidal activity with no toxicity to animals or microorganisms. We have developed the general routes for the spiro-hydantoin formation on sugars and applied the methodologies to the synthesis of 1 and its stereoisomers 2-8 and 1'-8'. Total synthesis of (+)-hydantocidin 1: The protected D-psicose 9, prepared from D-fructose in five steps, was stereospecifically converted to azide-amide 13 by N-glycosidation (TMSN_3, TMSOTf in CH_3CN), oxidation and amination. Spiro-hydantoin formation on 13 was achieved by aza-Wittig reaction (PBu_3, CO_2 in CH_3CN) to afford 15, which was acetylated in one pot to give 18 in 91% yield. Deprotection of 18 furnished the (+)-hydantocidin 1 without epimerization at the anomeric center. Synthesis of stereoisomers of 1: The aldol condensation of D- (or L-) threose 19 and hydantoin 20 gave the olefin isomers 21 and 22, which were cyclized under acidic condition (p-TsOH, dichloroethane) into key spiro-intermediates 23 and 24. They were also obtained from epoxy-aldehyde 25 and hydantoin 26 directly. Diastereoselective dihydroxylation (OsO_4 or mCPBA then aq.H_2SO_4) of the spiro-dihydrofurane 23,24,28 and 29 afforded the desired stereoisomers 30-34 and 37-40, which were deprotected to furnish the stereoisomers 1-8 (or 1'-8'), respectively.
天然有機化合物討論会の論文
1990-09-25