A Very Efficient Cerium(IV) Ammonium Nitrate Catalyzed, Four-Component Synthesis of Tetrahydropyridines and Its Application in the Concise Generation of Functionalized Homoquinolizine Frameworks
✍ Scribed by Vellaisamy Sridharan; Swarupananda Maiti; J. Carlos Menéndez
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 283 KB
- Volume
- 15
- Category
- Article
- ISSN
- 0947-6539
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✦ Synopsis
Abstract
Molecular diversity: A cerium(IV) ammonium nitrate (CAN) catalyzed, four‐component reaction from very simple acyclic starting materials afforded densely substituted tetrahydropyridines, which were transformed into homoquinolizines by using a γ‐alkylation–ring‐closing metathesis (RCM) sequence (see scheme).magnified image
The cerium(IV) ammonium nitrate (CAN) catalyzed, four‐component reaction between primary aliphatic amines, β‐ketoesters or β‐ketothioesters, α,β‐unsaturated aldehydes, and alcohols provided a very efficient and atom‐economical access to substituted 6‐alkoxy‐2‐methyl‐1,4,5,6‐tetrahydropyridines. These materials were then transformed into homoquinolizine derivatives in excellent yields by using a two‐step sequence comprised of regioselective γ‐deprotonation–allylation and ring‐closing metathesis reactions. The possibility of displacing the alkoxy group by allylsilane nucleophiles, presumably through a vinylogous acyliminium intermediate species, was also demonstrated.