29 タンデム型分子内Diels-Alder/1,3双極子環化反応を鍵反応としたVindoline並びに関連アルカロイド類の全合成(口頭発表の部)

概要

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A concise 11-step total synthesis of (-)- and ent-(+)-vindoline (3) is detailed based on a unique tandem intramolecular [4+2]/[3+2] cycloaddition cascade of a 1,3,4-oxadiazole inspired by the natural product structure, in which three rings and four C-C bonds are formed central to the characteristic pentacyclic ring system setting all six stereocenters and introducing essentially all the functionality found in the natural product in a single step. As key elements of the scope and stereochemical features of the reaction were defined, a series of related natural products of increasing complexity were also prepared by total synthesis including both enantiomers of vindorosine (4), minovine (31), 4-desacetoxy-6,7-dihydrovindorosine (32), and 4-desacetoxyvindorosine (48) as well as N-methylaspidospermidine (52). Subsequent extensions of the approach provided both enantiomers of dihydrovindoline (47), 4-desacetoxyvindoline (49), 4-desacetoxy-6,7-dihydrovindoline (50) and 4-desacetoxy-5-desethylvindoline (51).
天然有機化合物討論会の論文
2006-09-15