N-杂环卡宾-铜络合物

与所得络合物相关的电子效应和空间位阻效应相匹配，使得N-杂环卡宾配体(NHCs)成为设计作为催化剂的新型金属复合物的重要候选者。Nolan及其同事是使用NHC配体进行催化的先驱之一，他们报道了使用Cu-NHC进行各种催化转化的应用。α,β-不饱和酮和酯的共轭还原、酮的氢化硅烷化、末端烯烃的环丙烷化、烯化、卡宾转移反应、烯烃的氮杂环丙烷化和醛的亚甲基化（方案1）都是Cu-NHC复合物（特别是（IPr）CuCl）在现代催化手段中的一些实例。最后，这些催化剂具有空气和水分稳定性，可作为前体用于合成更多空气敏感复合物。¹

方案 1.

Nolan及其同事描述了在PPh₃、i-PrOH和TMSCHN₂存在下，在醛（和酮）的烯化中使用了Cu-Imes卡宾复合物5。虽然有报道称使用Wilkinson催化剂可进行类似的烯化，但含Cu替代品提供了更经济的解决方案。官能团相容性非常好，因此能够形成官能化的脂肪族烯烃、二烯和苯乙烯，含有硝基（众所周知它对这类反应有害）、三氟甲基、氨基和酯官能团以及用吡啶取代的杂芳族烯烃、吡咯和吲哚衍生物（方案2）。在略微改变的反应条件下，异丙基衍生的卡宾复合物6也被证明在这类反应中非常有用（方案3）。²

方案 2.

方案 3.

参考文献

1. Díez-González S, Scott NM, Nolan SP. 2006. Cationic Copper(I) Complexes as Efficient Precatalysts for the Hydrosilylation of Carbonyl Compounds. Organometallics. 25(9):2355-2358. https://doi.org/10.1021/om0600487

2. Díez-González S, Nolan SP. 2008. Copper, Silver, and Gold Complexes in Hydrosilylation Reactions. Acc. Chem. Res.. 41(2):349-358. https://doi.org/10.1021/ar7001655

3. Jurkauskas V, Sadighi JP, Buchwald SL. 2003. Conjugate Reduction of ?,?-Unsaturated Carbonyl Compounds Catalyzed by a Copper Carbene Complex. Org. Lett.. 5(14):2417-2420. https://doi.org/10.1021/ol034560p

4. Lebel H, Davi M, Díez-González S, Nolan SP. 2007. Copper?Carbene Complexes as Catalysts in the Synthesis of Functionalized Styrenes and Aliphatic Alkenes. J. Org. Chem.. 72(1):144-149. https://doi.org/10.1021/jo061781a

5. Trost BM, Dong G. 2006. New Class of Nucleophiles for Palladium-Catalyzed Asymmetric Allylic Alkylation. Total Synthesis of Agelastatin A. J. Am. Chem. Soc.. 128(18):6054-6055. https://doi.org/10.1021/ja061105q

6. Fructos MR, Belderrain TR, Nicasio MC, Nolan SP, Kaur H, Díaz-Requejo MM, Pérez PJ. 2004. Complete Control of the Chemoselectivity in Catalytic Carbene Transfer Reactions from Ethyl Diazoacetate:  AnN-Heterocyclic Carbene?Cu System That Suppresses Diazo Coupling. J. Am. Chem. Soc.. 126(35):10846-10847. https://doi.org/10.1021/ja047284y

7. Kaur H, Zinn FK, Stevens ED, Nolan SP. 2004. (NHC)CuI(NHC = N-Heterocyclic Carbene) Complexes as Efficient Catalysts for the Reduction of Carbonyl Compounds. Organometallics. 23(5):1157-1160. https://doi.org/10.1021/om034285a

8. Díez-González S, Nolan SP. 2008. N-heterocyclic carbene-copper complexes: Synthesis and applications in catalysis . [Internet]. Aldrichimica Acta2008, 41, 43. .

9. Lebel H, Davi M, Díez-González S, Nolan SP. 2007. Copper?Carbene Complexes as Catalysts in the Synthesis of Functionalized Styrenes and Aliphatic Alkenes. J. Org. Chem.. 72(1):144-149. https://doi.org/10.1021/jo061781a