研究室工作進展 Jul 19th, 2010
研究室工作進展 July 19, 2010
1,4-Dilithio-1,3-dienes: Reaction and Synthetic Applications
Zhenfeng Xi
Acc. Chem. Res. 2010, ASAP on 0715
The development of organometallic reagents remains one of the most important frontiers in synthetic chemistry. Commonly used organometallic reagents (such as RLi and RMgBr) are typically monometallic compounds, although they aggregate in many cases. When two carbon-metal bonds are in the same molecule in close proximity, however, these two carbon-metal moieties may exhibit novel reactivity. In this Account, we outline our work on new reactions and synthetic applications of the organo-dilithio reagents 1,4-dilithio-1,3-butadienes.
The 1,4-dilithio-1,3-butadienes can be accessed readily in high efficiency with a wide variety of substitution patterns on the butadienyl skeleton. The configuration has been predicted and demonstrated to favor a double dilithium bridging structure in both solution and solid states. The two Li atoms are bridged by a butadiene moiety and are in close proximity. By taking advantage of this unique configuration, we have developed useful and interesting synthetic methodologies.
Three types of reactions of 1,4-dilithio-1,3-butadienes, termed dilithio reagents here, have been developed and are discussed. An intramolecular reaction is introduced in the first section. The reaction is a result of the intra-cooperative effect among the two C-Li moieties, the butadienyl bridge, and the substituents. A useful transformation from silylated 1,4-dilithio-1,3-butadienes to α-lithio siloles is described.
Second, we discuss an intermolecular reaction that results from the inter-cooperative effect of the two C-Li moieties towards substrates. As an example of the formation of functionalized cyclic dianions from the linear dianions of the dilithio reagents and organic substrates, we describe the isolation and structural characterization of a novel type of cyclic dianion-that is, fully substituted oxy-cyclopentadienyl dilithium formed via the reaction of dilithio reagents with CO. We also describe diverse reactions of dilithio reagents with nitriles to form substituted pyridines, tricyclic 1-bipyrrolines, and siloles, demonstrating the remarkable effect of substituents on the butadienyl skeleton.
Third, we discuss transmetallation of dilithio reagents to generate other organo-dimetallic compounds. This section focuses on organo-dicopper compounds and their reactivity toward the synthesis of strained ring systems-such as semibullvalenes and twisted four-membered rings-with the metal-mediated C-C bond-forming approach. In addition to these three representative reactions, other useful applications are also briefly introduced.
The dimetallic 1,4-dilithio-1,3-butadienes and their transmetallated derivatives provide unique synthetic organometallic reagents that are very different from monometallic reagents, both in terms of reactivity and synthetic application. These organo-dimetallic reagents provide access to interesting and useful compounds that are not available by other means. Moreover, given the possibilities afforded, the study of organo-dimetallic and organo-polymetallic compounds should yield further synthetic applications in the near future.
該工作背景說明
金屬有機化合物作為合成試劑廣泛應用于合成化學有關的各個領域，一直受到學術界和工業界的極大關注。常見的金屬有機合成試劑如有機锂試劑、格氏試劑等都是單金屬試劑。從概念上講，如果一個分子中存在兩個或者多個碳-金屬鍵，則構成雙或者多金屬有機化合物。雙或者多金屬有機化合物中的碳-金屬鍵之間，在有機橋聯的配合下，将可能發生協同作用，經過與底物作用後生成的物種也可能進一步發生協同作用，從而表現出不同于其相應單金屬試劑的反應類型，甚至表現出全新的反應模式。本研究小組1999年首先認識到了雙金屬有機化合物（1,4－二锂－1,3－丁二烯衍生物）的特殊反應性能，經過10餘年深入、系統的研究，将1,4－二锂－1,3－丁二烯衍生物逐漸發展成新型有機锂試劑。處于同一分子内的二個锂原子空間上可以靠得較近，從而産生“協同效應”，在與各類有機底物反應時顯示出不同于有機單锂試劑的特殊反應化學和新反應類型。該研究不僅為發展新型金屬有機試劑提供了新思路，可以合成已知方法不能夠得到的化合物或者結構類型，同時為研究配位化學中雙金屬的協同作用提供了模型。本小組在雙锂試劑的基礎上，進一步展開了其它雙金屬有機化合物如雙銅（雙稀土、異雙金屬等）金屬有機化合物的合成與應用研究，并将該類化合物統稱為“雙金屬有機合成試劑”(Organo-di-metallic reagents)。
金屬有機化合物作為合成試劑廣泛應用于合成化學有關的各個領域，一直受到學術界和工業界的極大關注。常見的金屬有機合成試劑如有機锂試劑、格氏試劑等都是單金屬試劑。從概念上講，如果一個分子中存在兩個或者多個碳-金屬鍵，則構成雙或者多金屬有機化合物。雙或者多金屬有機化合物中的碳-金屬鍵之間，在有機橋聯的配合下，将可能發生協同作用，經過與底物作用後生成的物種也可能進一步發生協同作用，從而表現出不同于其相應單金屬試劑的反應類型，甚至表現出全新的反應模式。本研究小組1999年首先認識到了雙金屬有機化合物（1,4－二锂－1,3－丁二烯衍生物）的特殊反應性能，經過10餘年深入、系統的研究，将1,4－二锂－1,3－丁二烯衍生物逐漸發展成新型有機锂試劑。處于同一分子内的二個锂原子空間上可以靠得較近，從而産生“協同效應”，在與各類有機底物反應時顯示出不同于有機單锂試劑的特殊反應化學和新反應類型。該研究不僅為發展新型金屬有機試劑提供了新思路，可以合成已知方法不能夠得到的化合物或者結構類型，同時為研究配位化學中雙金屬的協同作用提供了模型。本小組在雙锂試劑的基礎上，進一步展開了其它雙金屬有機化合物如雙銅（雙稀土、異雙金屬等）金屬有機化合物的合成與應用研究，并将該類化合物統稱為“雙金屬有機合成試劑”(Organo-di-metallic reagents)。
十餘年來本小組在雙金屬有機合成試劑的發現與發展方面發表的部分代表性原始論文如下。
1 Zhenfeng Xi,* and Qiuling Song,
J. Org. Chem. 2000, 65, 9157-9159.
2 Zhenfeng Xi,* Qiuling Song, Jinglong Chen, Hairong Guan, and Pixu Li,
Angew. Chem. Int. Ed. 2001, 40, 1913-1916.
3 Qiuling Song, Jinglong Chen, Xianglin Jin, and Zhenfeng Xi,*
J. Am. Chem. Soc. 2001, 123, 10419-10420
4 Jinglong Chen, Qiuling Song, Congyang Wang, and Zhenfeng Xi,*
J. Am. Chem. Soc. 2002, 124, 6238-6239.
5 Hongyun Fang, Guotao Li, Guoliang Mao, and Zhenfeng Xi,*
Chem. Eur. J. 2004, 10, 3444-3450.
6 Chao Wang, Jian Yuan, Guotao Li, Zitao Wang, Shiwei Zhang, and Zhenfeng Xi,*
J. Am. Chem. Soc. 2006, 128, 4564-4565.
7 Chao Wang, Qian Luo, Hui Sun, Xiangyu Guo, and Zhenfeng Xi,*
J. Am. Chem. Soc. 2007, 129, 3094-3095.
8 Nan Yu, Congyang Wang, Fei Zhao, Wen-Xiong Zhang, and Zhenfeng Xi*,
Chem. Eur. J. 2008, 14, 5670-5679.
9 Qian Luo, Chao Wang, Wen-Xiong Zhang, and Zhenfeng Xi*
Chem. Commun. 2008, 1593-1595.
10 Lantao Liu, Wen-Xiong Zhang, Chao Wang, Congyang Wang, and Zhenfeng Xi*
Angew. Chem. Int. Ed. 2009, 48, 8111-8114.
11 Lantao Liu, Wen-Xiong Zhang, * Qian Luo, Heng Li, and Zhenfeng Xi*
Organometallics 2010, 29, 278-281