Nickel-Catalyzed Reductive Cyclization of Alkyl Dihalides
摘要:
The reductive coupling protocol to intra-molecular cyclization of dihaloalkanes is presented. It leads to five- and six-membered rings, with the former being more efficient. The incorporation of secondary alkyl halides generally promotes coupling, efficiency. To the best of our know ledge this is the first catalytic ring closure reaction arising form dihaloalkanes under chemical reductive conditions.
作者:Fumihiko Toriyama、Josep Cornella、Laurin Wimmer、Tie-Gen Chen、Darryl D. Dixon、Gardner Creech、Phil S. Baran
DOI:10.1021/jacs.6b07172
日期:2016.9.7
single electron transfer using Ni and Fe catalyst systems have been studied extensively, and separately, for decades. Here we demonstrate the first couplings of redox-active esters (both isolated and derived in situ from carboxylic acids) with organozinc and organomagnesium species using an Fe-based catalyst system originally developed for alkyl halides. This work is placed in context by showing a direct
几十年来,基于单电子转移使用 Ni 和 Fe 催化剂体系的烷基卤化物和有机金属物种的交叉偶联已被广泛且分别地研究。在这里,我们展示了氧化还原活性酯(从羧酸中分离和原位衍生)与有机锌和有机镁物种的首次偶联,使用最初为烷基卤化物开发的 Fe 基催化剂体系。这项工作通过展示与 Ni 催化剂的直接比较来放置在上下文中,涉及超过 40 个示例,涵盖一系列初级、二级和三级底物。这种新的 C-C 耦合具有可扩展性和可持续性,并且在某些情况下比其基于 Ni 的耦合表现出许多明显的优势。
Nickel-Catalyzed Decarboxylative Alkylation of Aryl Iodides with Anhydrides
scope of aliphatic carboxylic anhydrides and tolerates synthetically useful aromatic substituents. Assisted by a redox system of pyridine N-oxide and zinc additives, the current reaction occurs under mild conditions and without the assistance of photocatalyst. Notably, this method features high chemoselectivity toward alkyl migration with mixed aliphatic/aromatic anhydrides. Thus, it provides a powerful
The generation of tertiary, secondary, and primary alkyl radicals has been achieved by the direct visible-light excita-tion of a boracene-based alkylborate. This system is based on the photophysical properties of the organoboron mole-cule. The protocol is applicable to decyanoalkylation, Giese addition, and nickel-catalyzed carbon-carbon bond for-mations such as alkyl-aryl cross-coupling or vicinal
Deacylative transformations of ketones via aromatization-promoted C–C bond activation
作者:Yan Xu、Xiaotian Qi、Pengfei Zheng、Carlo C. Berti、Peng Liu、Guangbin Dong
DOI:10.1038/s41586-019-0926-8
日期:2019.3
3-dienes. Specifically, the acyl group is removed from the ketone and transformed to a pyrazole, and the resulting alkyl fragment undergoes various transformations. These include the deacetylation of methyl ketones, carbenoid-free formal homologation of aliphatic linear ketones and deconstructive pyrazole synthesis from cyclic ketones. Given that ketones are prevalent in feedstock chemicals, natural products
Ruphos-mediated Suzuki cross-coupling of secondary alkyl trifluoroborates
作者:Adri van den Hoogenband、Jos H.M. Lange、Jan Willem Terpstra、Melle Koch、Gerben M. Visser、Martin Visser、Ties J. Korstanje、Johann T.B.H. Jastrzebski
DOI:10.1016/j.tetlet.2008.04.129
日期:2008.6
A Ruphos-mediated Suzukicross-coupling between (hetero)aryl bromides and secondary alkyltrifluoroborates is described using palladium catalysis. The Ruphos ligand showed superior properties as compared to S-Phos in this type of reaction. This method constitutes a valuable extension to current methods for the straightforward production of secondary-alkylated (hetero)aryl derivatives.