Studies on the Enantioselective Synthesis of E-Ethylidene-bearing Spiro[indolizidine-1,3′-oxindole] Alkaloids
A synthetic route for the enantioselective construction of the tetracyclic spiro[indolizidine-1,3'-oxindole] framework present in a large number of oxindole alkaloids, with a cis H-3/H-15 stereochemistry, a functionalized two-carbon substituent at C-15, and an E-ethylidene substituent at C-20,...
| Authors: | , , , , |
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| Format: | article |
| Status: | Published version |
| Publication Date: | 2021 |
| Country: | España |
| Institution: | Universidad de Barcelona |
| Repository: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/173571 |
| Online Access: | https://hdl.handle.net/2445/173571 |
| Access Level: | Open access |
| Keyword: | Alcaloides Enantiòmers Compostos heterocíclics Síntesi orgànica Alkaloids Enantiomers Heterocyclic compounds Organic synthesis |
| Summary: | A synthetic route for the enantioselective construction of the tetracyclic spiro[indolizidine-1,3'-oxindole] framework present in a large number of oxindole alkaloids, with a cis H-3/H-15 stereochemistry, a functionalized two-carbon substituent at C-15, and an E-ethylidene substituent at C-20, is reported. The key steps of the synthesis are the generation of the tetracyclic spirooxindole ring system by stereoselective spirocyclization from a tryptophanol-derived oxazolopiperidone lactam, the removal of the hydroxymethyl group, and the stereoselective introduction of the E-ethylidene substituent by acetylation at the -position of the lactam carbonyl, followed by hydride reduction and elimination. Following this route, the 21-oxo derivative of the enantiomer of the alkaloid 7(S)-geissoschizol oxindole has been prepared. |
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