Stereoselective Synthesis of 2,4,5-Trisubstituted Piperidines via Radical Cyclization
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- 作者：Maria-Eleni Ragoussi ; Stephen M. Walker ; Andrea Piccanello ; Benson M. Kariuki ; Peter N. Horton ; Neil Spencer ; John S. Snaith
- 刊名：Journal of Organic Chemistry
- 出版年：2010
- 出版时间：November 5, 2010
- 年：2010
- 卷：75
- 期：21
- 页码：7347-7357
- 全文大小：1066K
- 年卷期：v.75,no.21(November 5, 2010)
- ISSN：1520-6904
文摘
A novel approach to 2,4,5-trisubstituted piperidines is reported, involving the 6-exo cyclization of stabilized radicals onto α,β-unsaturated esters. Only two of the four possible diastereoisomers are observed, with diastereomeric ratios ranging from 3:2 to 40:1 when the radical stabilizing group is vinyl or phenyl. Cyclization of a (triethylsilyl)vinyl-stabilized radical gives the corresponding piperidine radical as a single diastereoisomer that may either be trapped by tributyltin hydride to afford the 2,4,5-trisubstituted piperidine or undergo a second 5-endo cyclization onto the (triethylsilyl)vinyl substituent to produce the 3,5,7-trisubstituted octahydro[2]pyrindene as a single diastereoisomer.