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- Title
Synthesis of Aristotelia-Type Alkaloids. Part XII. Total synthesis of (−)-tasmanine. Stereoelectronic factors that control the rearrangement of 3 H-indol-3-ol derivatives to oxindoles ( = 1,3-dihydro-2 H-indol-2-ones) or to pseudoindoxyls ( =1,2-dihydro-3 H-indol-3-ones)
- Authors
Güller, Rolf; Borschberg, Hans-Jürg
- Abstract
The oxidative transformation of (+)-aristoteline ((+)- 5) into its metabolites, the recently synthesized indole alkaloids (−)-serratoline ((−)- 6), (+)-aristotelone ((+)- 2), and (−)-alloaristoteline ((−)- 22), was investigated in more detail. It was demonstrated that the diastereoface selectivity of the reaction of (+)- 5 with 3-chloroperbenzoic acid can be altered by variation of the solvent as well as by addition of CF3COOH. The chemoselectivity of the 1,2-rearrangement of the intermediate 3 H-indol-3-ol derivatives could be controlled as follows: treatment of 3 H-indol-3-ols with aqueous polyphosphoric acid led to the pseudoindoxyl ( = 1,2-dihydro-3 H-indol-3-one) derivatives, whereas an analogous treatment of the corresponding O-benzoates furnished exclusively the corresponding, constitutionally isomeric 2-oxindole ( = 1,3-dihydro-2 H-indol-2-one) products. Exploitation of these and related findings led to efficient total syntheses of the Aristotelia alkaloid (−)-tasmanine ((−)- 1) and of the corresponding unnatural epimer (+)- 12, as well as of the two pseudoindoxyls (+)-aristotelone ((+)- 2) and (−)-2-epiaristotelone ((−)- 11). All these transformations were carried out with synthetic (+)-aristoteline ((+)- 5) as the single indole alkaloid precursor.
- Publication
Helvetica Chimica Acta, 1993, Vol 76, Issue 5, p1847
- ISSN
0018-019X
- Publication type
Article
- DOI
10.1002/hlca.19930760505