醇脱氧领域的一个长期科学挑战是在存在其他官能团(如广泛存在于生物分子中的游离羟基和胺)的情况下,具有高选择性和高效率的直接催化 sp(3) CO 去官能化。以前,选择性问题只能通过使用化学计量试剂的经典多步脱氧策略来解决。在此,我们提出了一种基于脱氢/沃尔夫-基什纳 (WK) 还原的催化后过渡金属催化氧化还原设计,以同时解决步骤经济性和选择性方面的挑战。我们假设的早期发展侧重于主要使用活化醇有效的铱催化过程,这决定了苛刻的反应条件,从而限制了其合成效用。之后,采用钌配合物在脂肪族伯醇脱氧方面取得了重大进展,在实际反应条件下具有良好的官能团耐受性和专属选择性。在简单和复杂的分子设置中,其卓越的效率以及完全的化学和区域选择性进一步说明了其合成效用。实验支持还包括机械讨论。总体而言,我们目前的方法成功地解决了相关领域中的上述挑战,为脂肪族伯醇的直接 sp(3) CO 去官能化提供了一种实用的基于
Cross-Coupling of Nonactivated Alkyl Halides with Alkynyl Grignard Reagents: A Nickel Pincer Complex as the Catalyst
作者:Oleg Vechorkin、Aurélien Godinat、Rosario Scopelliti、Xile Hu
DOI:10.1002/anie.201105964
日期:2011.12.2
In a pinch: The nickel pincer complex 1 catalyzes the cross‐coupling of the title compounds with remarkable substrate scope and functional group tolerance. A nickel/alkynyl species was isolated and shown to be catalytically competent. THF=tetrahydrofuran, O‐TMEDA=bis[2‐(N,N‐dimethylaminoethyl)] ether.
Ni-Catalyzed Sonogashira Coupling of Nonactivated Alkyl Halides: Orthogonal Functionalization of Alkyl Iodides, Bromides, and Chlorides
作者:Oleg Vechorkin、Delphine Barmaz、Valérie Proust、Xile Hu
DOI:10.1021/ja906040t
日期:2009.9.2
Ni-catalyzed Sonogashira coupling of nonactivated, beta-H-containing alkyl halides, including chlorides, is reported. The coupling is tolerant to a wide range of functional groups, including ether, ester, amide, nitrile, keto, heterocycle, acetal, and aryl halide, in both coupling partners. The coupling can be selective for a specific C-X bond (X = I, Br, Cl) and allows for orthogonal functionalization
Synthesis and Characterization of Soluble and n-Dopable Poly(quinoxaline vinylene)s and Poly(pyridopyrazine vinylene)s with Relatively Small Band Gap
作者:Maria Jonforsen、Tomas Johansson、Olle Inganäs、Mats R. Andersson
DOI:10.1021/ma0111111
日期:2002.2.1
Synthesis and characterization of poly(quinoxaline vinylene)s and poly(pyridopyrazine vinylene)s with linear and branched aliphatic side chains are reported. The electron affinity of the polymers was measured with cyclic voltammetry (CV) and found to be highest for the pyridopyrazine vinylene polymers. Compared to CN-MEH-PPV, the pyridopyrazine vinylene polymers were easier to reduce, while the quinoxaline
N-Heterocyclic carbene copper-catalyzed direct alkylation of terminal alkynes with non-activated alkyl triflates
作者:Liqun Jin、Wangfang Hao、Jianeng Xu、Nan Sun、Baoxiang Hu、Zhenlu Shen、Weimin Mo、Xinquan Hu
DOI:10.1039/c7cc00891k
日期:——
(NHC)-Cu-catalyzed C(sp)-C(sp3) bond formation has been successfully achieved under mild conditions. Nonactivated alkyl triflates, which could be easily derived from alcohols, were utilized as C-O electrophiles. Mechanistic studies suggested that...
Nickel-Catalyzed Direct Alkylation of Terminal Alkynes at Room Temperature: A Hemilabile Pincer Ligand Enhances Catalytic Activity
作者:Pablo M. Pérez García、Peng Ren、Rosario Scopelliti、Xile Hu
DOI:10.1021/cs501502u
日期:2015.2.6
we describe the design and development a new nickel pincer complex that catalyzes the direct coupling of primary alkyl halides with terminalalkynes at roomtemperature. The catalysis has a good substrate scope and high functional group tolerance. Kinetic data suggest that the new pincer ligand is hemilabile, and the dissociation of a labile amine donor is the turnover-determining step of the catalysis