Synthetic indole alkaloids.II. A two step synthesis of 4-carbethoxy-3-ethylenedioxybutyraldehyde; a pentacyclic alkaloid precursor
✍ Scribed by Frederick V. Brutcher Jr.; Harry Hinney
- Publisher
- Elsevier Science
- Year
- 1979
- Tongue
- French
- Weight
- 105 KB
- Volume
- 20
- Category
- Article
- ISSN
- 0040-4039
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✦ Synopsis
Our recently synthesized' pentacyclic ester lactam(l) represents a central intermediate for preparing, with proper structural variations, reserpinoid and yohimbinoid molecules2 since itsD/E ring junction reduces cis 1 while maintaining an epimerizable C20 hydrogen for possible conversion toD/E trans. However, its utility has been seriously limited by a lengthy eight step synthesis of low overall yield (1.5%). Of these eight synthetic steps, six were used to transform ethyl acetone dicarboxylate via its ketal(2) to the aldehydo ester-(). Reaction of 2 with tryptamine gave the tetracyclic keto lactam(&) which on treatment with carbethoxy methyl vinyl ketone gave 1.