研究室工作进展 Jul 19th, 2010
研究室工作进展 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.
该工作背景说明
金属有机化合物作为合成试剂广泛应用于合成化学有关的各个领域，一直受到学术界和工业界的极大关注。常见的金属有机合成试剂如有机锂试剂、格氏试剂等都是单金属试剂。从概念上讲，如果一个分子中存在两个或者多个碳-金属键，则构成双或者多金属有机化合物。双或者多金属有机化合物中的碳-金属键之间，在有机桥联的配合下，将可能发生协同作用，经过与底物作用后生成的物种也可能进一步发生协同作用，从而表现出不同于其相应单金属试剂的反应类型，甚至表现出全新的反应模式。本研究小组1999年首先认识到了双金属有机化合物（1,4－二锂－1,3－丁二烯衍生物）的特殊反应性能，经过10余年深入、系统的研究，将1,4－二锂－1,3－丁二烯衍生物逐渐发展成新型有机锂试剂。处于同一分子内的二个锂原子空间上可以靠得较近，从而产生“协同效应”，在与各类有机底物反应时显示出不同于有机单锂试剂的特殊反应化学和新反应类型。该研究不仅为发展新型金属有机试剂提供了新思路，可以合成已知方法不能够得到的化合物或者结构类型，同时为研究配位化学中双金属的协同作用提供了模型。本小组在双锂试剂的基础上，进一步展开了其它双金属有机化合物如双铜（双稀土、异双金属等）金属有机化合物的合成与应用研究，并将该类化合物统称为“双金属有机合成试剂”(Organo-di-metallic reagents)。
金属有机化合物作为合成试剂广泛应用于合成化学有关的各个领域，一直受到学术界和工业界的极大关注。常见的金属有机合成试剂如有机锂试剂、格氏试剂等都是单金属试剂。从概念上讲，如果一个分子中存在两个或者多个碳-金属键，则构成双或者多金属有机化合物。双或者多金属有机化合物中的碳-金属键之间，在有机桥联的配合下，将可能发生协同作用，经过与底物作用后生成的物种也可能进一步发生协同作用，从而表现出不同于其相应单金属试剂的反应类型，甚至表现出全新的反应模式。本研究小组1999年首先认识到了双金属有机化合物（1,4－二锂－1,3－丁二烯衍生物）的特殊反应性能，经过10余年深入、系统的研究，将1,4－二锂－1,3－丁二烯衍生物逐渐发展成新型有机锂试剂。处于同一分子内的二个锂原子空间上可以靠得较近，从而产生“协同效应”，在与各类有机底物反应时显示出不同于有机单锂试剂的特殊反应化学和新反应类型。该研究不仅为发展新型金属有机试剂提供了新思路，可以合成已知方法不能够得到的化合物或者结构类型，同时为研究配位化学中双金属的协同作用提供了模型。本小组在双锂试剂的基础上，进一步展开了其它双金属有机化合物如双铜（双稀土、异双金属等）金属有机化合物的合成与应用研究，并将该类化合物统称为“双金属有机合成试剂”(Organo-di-metallic reagents)。
十余年来本小组在双金属有机合成试剂的发现与发展方面发表的部分代表性原始论文如下。
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