Stereochemical evidence for aryl participation in the ring opening of oxiranes. Ring-opening reactions of 1-benzyl-1,2-epoxycyclohexane under acidic conditions
Catalytic Dehydration of Benzylic Alcohols to Styrenes by Rhenium Complexes
作者:Ties J. Korstanje、Johann T. B. H. Jastrzebski、Robertus J. M. Klein Gebbink
DOI:10.1002/cssc.201000055
日期:——
The oxygen content of biomass‐based materials can be reduced by selective dehydration of hydroxyl groups. As a first step towards biomass‐based chemicals, rhenium‐based catalysts are shown to be active in the dehydration of various benzylic alcohols to styrene moieties. The turnover frequencies are superior to the benchmark catalyst sulfuric acid, without sacrificing any selectivity.
According to “integrated chemical process”, a novel one-pot process for construction of highly substituted allylic moieties has been achieved. A series of alkylation of allylic sulfones and palladium-catalyzed reductive desulfonylation by use of LiBHEt3 is integrated. The double alkylation furnishes more substituted olefins. Use of arylzinc compounds in place of the hydride enables electrophilic a
Cobalt co-catalysis for cross-electrophile coupling: diarylmethanes from benzyl mesylates and aryl halides
作者:Laura K. G. Ackerman、Lukiana L. Anka-Lufford、Marina Naodovic、Daniel J. Weix
DOI:10.1039/c4sc03106g
日期:——
of aryl halides with alkyl radicals derived fromalkyl halides has recently been extended to couplings with carbon radicals generated by a co-catalyst. In this study, a new co-catalyst, cobalt phthalocyanine (Co(Pc)), is introduced and demonstrated to be effective for coupling substrates not prone to homolysis. This is because Co(Pc) reacts with electrophiles by an SN2 mechanism instead of by the electron-transfer
镍催化的芳基卤化物与衍生自烷基卤化物的烷基的交叉偶联最近已扩展到与助催化剂产生的碳自由基的偶联。在这项研究中,引入了一种新的助催化剂——酞菁钴(Co(Pc)),并被证明对偶联不易均裂的底物有效。这是因为 Co(Pc) 通过 S N 2 机制而不是之前探索的电子转移或卤素抽象机制与亲电子试剂发生反应。研究证明了 (bpy)Ni 和 Co(Pc) 的正交反应性,将这种选择性应用于甲磺酸苄酯与芳基卤的偶联,以及将这些条件适应于反应性较低的磷酸苄酯和对映体收敛反应。
Nickel-Catalyzed Cross-Coupling of Anisoles with Alkyl Grignard Reagents via C–O Bond Cleavage
作者:Mamoru Tobisu、Tsuyoshi Takahira、Naoto Chatani
DOI:10.1021/acs.orglett.5b02200
日期:2015.9.4
Nickel-catalyzed cross-coupling of methoxyarenes with alkylGrignardreagents, which involves the cleavage of the C(aryl)–OMe bond, has been developed. The use of 1,3-dicyclohexylimidazol-2-ylidene as a ligand allows the introduction of a variety of alkyl groups, including Me, Me3SiCH2, ArCH2, adamantyl, and cyclopropyl. The method can also be used for the alkylative elaboration of complex molecules
已经开发了镍催化的甲氧基芳烃与烷基格氏试剂的交叉偶联,这涉及到C(芳基)-OMe键的裂解。使用1,3-二环己基咪唑-2-亚烷基作为配体允许引入各种烷基,包括Me,Me 3 SiCH 2,ArCH 2,金刚烷基和环丙基。该方法还可用于带有C(芳基)–OMe键的复杂分子的烷基化修饰。
Copper-Catalyzed Alkene Arylation with Diaryliodonium Salts
作者:Robert J. Phipps、Lindsay McMurray、Stefanie Ritter、Hung A. Duong、Matthew J. Gaunt
DOI:10.1021/ja3039807
日期:2012.7.4
synthetic organic chemistry. We report a new approach to alkene arylation using diaryliodoniumsalts and Cu catalysis. Using a range of simple alkenes, we have shown that the product outcomes differ significantly from those commonly obtained by the Heck reaction. We have used these insights to develop a number of new tandem and cascade reactions that transform readily available alkenes into complex arylated