Cycloaddition Reactions of 1-Lithio-1,3-dienes with Aromatic Nitriles Affording Multiply Substituted Pyridines, Pyrroles, and Linear Butadienylimines

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• 作者：Congyang Wang ; Zhihui Wang ; Lantao Liu ; Chao Wang ; Guangzhen Liu ; Zhenfeng Xi
• 刊名：Journal of Organic Chemistry
• 出版年：2006
• 出版时间：October 27, 2006
• 年：2006
• 卷：71
• 期：22
• 页码：8565 - 8571
• 全文大小：176K
• 年卷期：v.71,no.22(October 27, 2006)
• ISSN：1520-6904

文摘

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Fully or partially substituted 1-iodo- or 1-bromo-1,3-dienes could be readily lithiated using t-BuLi orn-BuLi to afford their corresponding 1-lithio-1,3-diene derivatives in quantitative yields. When these insitu generated lithium reagents were treated with organonitriles, depending on the substitution patternsof the butadienyl skeletons, substituted pyridines, pyrroles, and/or linear butadienyl imines were formedin good to excellent yields via N-lithioketimine intermediates. In the cases of 1,2,3,4-tetrasubstituted and2,3-disubstituted 1-lithio-1,3-dienes, pyridine derivatives or linear butadienyl imines were generally formeddepending on the reaction temperatures. When 1,2,3,4-tetrasubstituted 4-halo-1-lithio-1,3-dienes and 1,2-disubstituted 1-lithio-1,3-dienes were treated with organonitriles, pyrrole derivatives or linear butadienylimines were obtained. Competition between 5-exo and 6-endo cyclization was found to be responsiblefor the formation of either pyrroles or pyridines. Selective elimination of RLi from the lithiated cyclicN-containing intermediates was observed. The order of elimination was found to be LiCl > Me₃SiLi >LiH.