A palladium-catalyzed oxidative cascade cyclization reaction has been developed to prepare pyrrolizidine and indolizidine derivatives from simple aliphatic alkenyl amides 2.1ak in one step in moderate to good yields, using Pd(TFA)2 as the catalyst and molecular oxygen (1 atm) as a green oxidant. This cascade cyclization can also proceed for ring-containing unsaturated amides 2.1ln to afford azatricyclic systems.
Palladium(II)-catalyzed dehydrohalogenation cascade cyclization reactions have been developed to synthesize polycyclic pyrrolizidine derivatives from iodoalkenylanilides 4.1ai in satisfactory to excellent yields under mild conditions. This reaction produces two stereocenters in one step and only one single diastereomer was obtained in the cyclization of 4.1. The reaction is proposed to proceed through an organopalladium(IV) species, formed by oxidative addition after the aminopalladation. This organopalladium(IV) species then undergoes reductive elimination to give the cyclized product. This cyclization is a fast and efficient way to construct natural alkaloids that contain pyrrolizidine or indolizidine cores. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/174527 |
| Date | January 2012 |
| Creators | Lo, Kai-yip., 羅啟業. |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Source | http://hub.hku.hk/bib/B47849691 |
| Rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works., Creative Commons: Attribution 3.0 Hong Kong License |
| Relation | HKU Theses Online (HKUTO) |
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