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1.
The first transition-metal-catalyzed activation of silyl C(sp(3))-H bond was realized and synthetically applied. A variety of organic skeletons substituted with SiMe(3) groups could undergo the Pd-catalyzed intramolecular coupling reaction, resulting in an unprecedented synthetic method for yielding six-membered silacycles. It was found that the adjacent Si atom played an essential role for the activation of the C(sp(3))-H bond of the SiMe(3) group; no activation reaction of the C(sp(3))-H bond of the CMe(3) group took place under the same reaction conditions. 相似文献
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This communication describes a new palladium-catalyzed method for the oxygenation of unactivated sp3 C-H bonds. A wide variety of alkane substrates containing readily available oxime and/or pyridine directing groups are oxidized with extremely high levels of chemo-, regio-, and in some cases diastereoselectivity. The substrate scope of these reactions is discussed, and the high selectivities are rationalized on the basis of the requirements of putative palladium alkyl intermediates. 相似文献
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Hasegawa N Charra V Inoue S Fukumoto Y Chatani N 《Journal of the American Chemical Society》2011,133(21):8070-8073
The regioselective carbonylation of unactivated C(sp(3))-H bonds of aliphatic amides was achieved using Ru(3)(CO)(12) as a catalyst. The presence of a 2-pyridinylmethylamine moiety in the amide is crucial for a successful reaction. The reaction shows a preference for C-H bonds of methyl groups as opposed to methylene C-H bonds and tolerates a variety of functional groups. The stoichiometric reaction of an amide with Ru(3)(CO)(12) gave a dinuclear ruthenium complex in which the 2-pyridinylmethylamino moiety was coordinated to the ruthenium center in an N,N manner. 相似文献
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D. Ramesh 《Tetrahedron letters》2010,51(37):4898-7582
An efficient and simple method for the oxidative coupling of benzylic and allylic sp3 C-H bonds with active methylenic sp3 C-H bonds under metal-free conditions was developed by employing 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) as an oxidant. The reaction was shown to proceed smoothly for various 1,3-dicarbonyl compounds with a range of benzylic and allylic substrates in good to excellent yields. 相似文献
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Iron-catalyzed direct C-N bond formation between imidazoles and benzylic hydrocarbons is described. The reaction utilizes an inexpensive iron catalyst-oxidant system that is suitable for the coupling of a range of benzylic C-H bonds with various imidazoles. 相似文献
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Tian-Lu Ren Bao-Hua Xu Sajid Mahmood Ming-Xue Sun Suo-Jiang Zhang 《Tetrahedron》2017,73(20):2943-2948
A protocol for the cobalt-catalyzed oxidative esterification of allylic/benzylic C(sp3)–H bonds with carboxylic acids was developed in this work. Mechanistic studies revealed that C(sp3)–H bond activation in the hydrocarbon was the turnover-limiting step and the in-situ formed [Co(III)]Ot-Bu did not engage in hydrogen atom abstraction (HAA) of a C–H bond. This protocol was successfully incorporated into a synthetic pathway to β-damascenone that avoided the use of NBS. 相似文献
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The first catalytic alkynylation of unactivated C(sp(3))-H bonds has been accomplished. The method allows for the straightforward introduction of an ethynyl group into aliphatic acid derivatives under palladium catalysis. This new reaction can be applied to the rapid elaboration of complex aliphatic acids, for example, via azide/alkyne cycloaddition. 相似文献
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The palladium-catalyzed ortho-arylation of benzamides by aryl iodides has been demonstrated with the simplest amide CONH(2) as a directing group for the first time. This protocol can be applied to various benzamides and aryl iodides with both electron-donating and electron-withdrawing groups. In addition, the synthesized biphenyl-2-carboxamides can be further transformed to other biphenyl derivatives such as nitriles, carboxylic acids, carbamates, and amines. 相似文献
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A general protocol for direct transformation of unreactive C(sp(3))-H bonds to C(sp(3))-CN bonds has been developed. The C-H activation was effected by photoexcited benzophenone, and the generated carbon radical was subsequently trapped with tosyl cyanide to afford the corresponding nitrile in a highly efficient manner. The present methodology is widely applicable to versatile starting materials and, thus, serves as a powerful tool for selective one-carbon elongation for construction of architecturally complex molecules. 相似文献
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Palladium-catalyzed alkylations of sp2 and sp3 C-H bonds with either methylboroxine or alkylboronic acids were developed. Ag2O or AgCO3 is used as a crucial oxidant and promoter for the transmetalation step. Ether, ester, alcohol, and alkene functional groups are tolerated. A new C-H activation pathway differing from the cyclometalation process is elucidated using methylboroxine as the coupling partner. 相似文献
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One of the most challenging transformations in current organic chemistry is the catalytic carboxylation of a C(sp(3))-H bond using CO(2) gas, an inexpensive and ubiquitous C1 source. A sequential protocol for C(sp(3))-H carboxylation by employing a nitrogen-directed, metal-assisted, C-H activation/catalytic silylation reaction in conjunction with fluoride-mediated carboxylation with CO(2) was established. The carboxylation proceeded only at the benzylic C(sp(3))-Si bond, not at the aromatic C(sp(2))-Si, which is advantageous for further manipulations of the products. 相似文献
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A Cu(II) mediated oxidative C(sp(2))-H and C(sp(3))-H coupling protocol gives access to aza-oxindoles in good to excellent yield in the presence of NaOtBu as base and toluene as solvent. 相似文献
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Baudoin O 《Chemical Society reviews》2011,40(10):4902-4911
Transition-metal-catalyzed C-H bond arylation has recently emerged as a powerful tool for the functionalization of organic molecules that may complement or even replace traditional catalytic cross-couplings. While many efforts have focused on the arylation of arenes and heteroarenes in the past two decades, less studies have been devoted to the arylation of nonacidic C-H bonds of alkyl groups. This tutorial review highlights recent work in this active area. 相似文献
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A simple and efficient method of catalyst free for the sp3 C–H bond activation of methyl aza-arene and nucleophilic addition to tryptanthrins in DMF was developed. Importantly, the more efficient and green isolation strategy of the purification of the products by centrifugation with 90% yields was applied. 相似文献
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En Liang Yinrong Wu Jiewen Chen Wei Xiong Jinwu Zhao Xingang Yao Xiaodong Tang 《Tetrahedron》2019,75(52):130783
A new aerobic copper-catalyzed three-component synthesis of azaaryl-substituted quinazolines has been developed, which featured inexpensive methylazaarenes as C1 sources, easily available copper salts as the catalysts and O2 as a sole oxidant. The transformation had very good substrate applicability towards methylazaarenes, and various azaaryl-substituted quinazolines were obtained in moderate to good yields. 相似文献
18.
Various anilides have been directly ortho-acetoxylated through a Pd(OAc)2-catalyzed C-H bond activation process. The amide group in anilides was found to functionalize as an elegant directing group to convert aromatic sp(2) C-H bonds into C-O bonds in high regioselectivity with acetic acid as the acetate source and K(2)S(2)O(8) as the oxidant. 相似文献
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Zhang SY He G Zhao Y Wright K Nack WA Chen G 《Journal of the American Chemical Society》2012,134(17):7313-7316
We report the efficient synthesis of alkyl ethers by the functionalization of unactivated sp(3)- and sp(2)-hybridized C-H bonds. In the Pd(OAc)(2)-catalyzed, PhI(OAc)(2)-mediated reaction system, picolinamide-protected amine substrates undergo facile alkoxylation at the γ or δ positions with a range of alcohols, including t-BuOH, to give alkoxylated products. This method features a relatively broad substrate scope for amines and alcohols, inexpensive reagents, and convenient operating conditions. This method highlights the emerging value of unactivated C-H bonds, particularly the C(sp(3))-H bond of methyl groups, as functional groups in organic synthesis. 相似文献