72 キラルグリコール素子を利用する天然物の合成

概要

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Chirality inversion of chiral 1,2-, 1,3-, and 1,4-glycols (1a-c) has been established. When dimesylates (2a-c) of (1) are treated with potassium acetate in acetic anhydride at reflux temperature, virtually complete inversion occurs to give diacetates (4a-c), in excellent yields, which regenerate diols (1) with opposite chiralities on deacetylation. The reaction is proved to be preceeded by both neighboring group participation and S_N2 pathways in 1,2- and1,3-glycol systems, while exclusively by S_N2 pathway in 1,4-glycol system. Using the chiral glycols obtained as common synthons and(or)employing the inversion method established, syntheses of both enantiomers of an insect aggregation pheromone sulcatol (15), a monoterpene diene (20), a biosynthetic precursor of cholesterol desmosterol (22), marine steroids with "unnatural" configuration at 20 center (20S)-3β-hydroxycholenates (23), a carbapenem key synthetic intermediate (51), and an ant venomous pyrrolizidine alkaloid (70), have been achieved in chiral forms.
天然有機化合物討論会の論文
1983-09-15