ChemInform Abstract: Novel [1,5] Sigmatropic Rearrangements of Cyclohexadienones Generated from Fischer Carbene Complexes. A New Strategy for Installing the C-20 Angular Ethyl Group in Aspidospermidine Alkaloids.
✍ Scribed by John F. Quinn; Mary Ellen Bos; William D. Wulff
- Publisher
- John Wiley and Sons
- Year
- 2010
- Weight
- 39 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0931-7597
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✦ Synopsis
Novel [1,5] Sigmatropic Rearrangements of Cyclohexadienones Generated from Fischer Carbene Complexes.
A New Strategy for Installing the C-20 Angular Ethyl Group in Aspidospermidine Alkaloids.
-Treatment of the complex (I) with the alkyne (II) results in formation of the carbazole (III). However, on prolonged time (48h) the derivative (IV) is obtained via a novel [1,5] sigmatropic rearrangement. Rearrangement is not observed in the reaction of the complex (V). However, it is found that the product (VI) can undergo partial rearrangement in refluxing xylenes. This method can be applied for the synthesis of Aspidospermidine alkaloids. Starting from the phenyl complex (XII) the indanone (XIV) is obtained in addition to the rearranged cyclohexadienone (XIII). The reaction of the phenyl complex (XV) affords only indenes.