- Copper-Catalyzed Alkoxycarbonylation of Alkyl Iodides for the Synthesis of Aliphatic Esters: Hydrogen Makes the Difference
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A copper-catalyzed alkoxycarbonylation transformation of unactivated alkyl iodides has been developed. Various alkyl iodides can be converted into the corresponding tert-butyl esters in good yields. NaOtBu acts as both a nucleophile and a base. Moreover, other types of aliphatic esters can also be obtained in moderated yields if extra alcohols are added. Both primary and secondary alkyl alcohols can react successfully.
- Geng, Hui-Qing,Wu, Xiao-Feng
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p. 8062 - 8066
(2021/10/25)
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- A heavy-metal-free desulfonylative Giese-type reaction of benzothiazole sulfones under visible-light conditions
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A visible-light-induced desulfonylative Giese-type reaction has been developed. Essential to the success is the employment of Hantzsch ester to activate benzothiazole sulfones without any heavy-metal additives. Not only benzylic benzothiazole sulfones but also alkyl ones were viable substrates and reacted with electron-deficient alkenes and a propiol amide.
- Inuzuka, Toshiyasu,Iwama, Haruka,Ogawa, Daichi,Sengoku, Tetsuya,Yoda, Hidemi
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supporting information
p. 9858 - 9861
(2021/10/12)
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- Copper-Catalyzed Conjugate Addition of Carbonyls as Carbanion Equivalent via Hydrazones
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Copper-catalyzed conjugate addition is a classic method for forming new carbon-carbon bonds. However, copper has never showed catalytic activity for umpolung carbanions in hydrazone chemistry. Herein, we report a facile conjugate addition of hydrazone catalyzed by readily available copper complexes at room temperature. The employment of mesitylcopper(I) and electron-rich phosphine bidentate ligand is a key factor affecting reactivity. The reaction allows various aromatic hydrazones to react with diverse conjugated compounds to produce 1,4-adducts in yields of about 20 to 99%.
- Luo, Siyi,Peng, Marie,Querard, Pierre,Li, Chen-Chen,Li, Chao-Jun
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p. 13111 - 13117
(2021/09/18)
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- Preparation method of substituted butyrate derivatives
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The invention discloses a preparation method of substituted butyrate derivatives. The method specifically comprises the following steps: by taking compounds shown in a formula 1, a formula 2 and a formula 3 as raw materials, carrying out an illumination reaction process in the presence of a photocatalyst and a hydrogen transfer catalyst to obtain a target compound shown in a formula I through one-step reaction. The invention discloses a free radical-mediated olefin bifunctional reaction without a cyclopropanation intermediate. The reaction can realize a product which can be obtained through cyclopropanation and cyclopropane ring opening processes traditionally in one step. Meanwhile, the preparation method of the compound is simple, uses cheap and easily available compounds as raw materials, and has the beneficial effects of one-step synthesis, mild reaction conditions, fast reaction, low cost, less generated waste, simple and safe operation, high atom economy, high selectivity, extremely wide substrate applicability, high yield and the like.
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Paragraph 0153-0156
(2020/07/15)
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- Radical-Mediated Strategies for the Functionalization of Alkenes with Diazo Compounds
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One of the most common reactions of diazo compounds with alkenes is cyclopropanation, which occurs through metal carbene or free carbene intermediates. Alternative functionalization of alkenes with diazo compounds is limited, and a methodology for the addition of the elements of Z-CHR2 (with Z = H or heteroatom, and CHR2 originates from N2 CR2) across a carbon-carbon double bond has not been reported. Here we report a novel reaction of diazo compounds utilizing a radical-mediated addition strategy to achieve difunctionalization of diverse alkenes. Diazo compounds are transformed to carbon radicals with a photocatalyst or an iron catalyst through PCET processes. The carbon radical selectively adds to diverse alkenes, delivering new carbon radical species, and then forms products through hydroalkylation by thiol-assisted hydrogen atom transfer (HAT), or forms azidoalkylation products through an iron catalytic cycle. These two processes are highly complementary, proceed under mild reaction conditions, and show high functional group tolerance. Furthermore, both transformations are successfully performed on a gram-scale, and diverse γ-amino esters, γ-amino alcohols, and complex spirolactams are easily prepared with commercially available reagents. Mechanistic studies reveal the plausible pathways that link the two processes and explain the unique advantages of each.
- Su, Yong-Liang,Liu, Geng-Xin,Liu, Jun-Wen,Tram, Linh,Qiu, Huang,Doyle, Michael P.
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supporting information
p. 13846 - 13855
(2020/09/21)
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- Oxo-Rhenium-Catalyzed Radical Addition of Benzylic Alcohols to Olefins
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Although carbon radicals generated from a variety of alcohol derivatives have proven valuable in coupling and addition reactions, the direct use of alcohols as synthetically useful radical sources is less known. In this report, benzylic alcohols are shown to be effective radical precursors for addition reactions to alkenes when treated with triphenylphosphine or piperidine with the catalyst ReIO2(PPh3)2 (I).
- Bandari, Chandrasekhar,Nicholas, Kenneth M.
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p. 3320 - 3327
(2020/03/23)
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- Iron-Catalyzed Nucleophilic Addition Reaction of Organic Carbanion Equivalents via Hydrazones
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Earth-abundant and well-defined iron complexes are found to be cheap and effective catalysts for a series of "umpolung" nucleophilic additions of hydrazones. The new catalytic system not only maintains the broad substrate scope of an earlier expensive ruthenium system but also attains chemoselectivity of different kinds of carbonyl groups. Furthermore, the iron catalyst enables this reaction at ambient temperature.
- Li, Chen-Chen,Dai, Xi-Jie,Wang, Haining,Zhu, Dianhu,Gao, Jian,Li, Chao-Jun
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supporting information
p. 3801 - 3805
(2018/07/25)
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- Carbonyls as Latent Alkyl Carbanions for Conjugate Additions
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Conjugate addition of carbon nucleophiles to electron-deficient olefins is one of the most powerful methods for forming carbon–carbon bonds. Despite great achievements in controlling the selectivity, variation of the carbon nucleophiles remains largely underexplored, with this approach relying mostly on organometallic reagents. Herein, we report that naturally abundant carbonyls can act as latent carbon nucleophiles for conjugate additions through a ruthenium-catalyzed process, with water and nitrogen as innocuous byproducts. The key to our success is homogeneous ruthenium(II) catalysis, combined with phosphines as spectator ligands and hydrazine as the reducing agent. This chemistry allows the incorporation of highly functionalized alkyl fragments into a vast array of electron-deficient olefins under mild reaction conditions in a reaction complementary to the classical organometallic-reagent-based conjugate additions mediated or catalyzed by “soft” transition metals.
- Dai, Xi-Jie,Wang, Haining,Li, Chao-Jun
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supporting information
p. 6302 - 6306
(2017/05/19)
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- Mechanism of SmI2/amine/H2O-promoted chemoselective reductions of carboxylic acid derivatives (esters, acids, and amides) to alcohols
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Samarium(II) iodide-water-amine reagents have emerged as some of the most powerful reagents (E° = -2.8 V) for the reduction of unactivated carboxylic acid derivatives to primary alcohols under single electron transfer conditions, a transformation that had been considered to lie outside the scope of the classic SmI2 reductant for more than 30 years. In this article, we present a detailed mechanistic investigation of the reduction of unactivated esters, carboxylic acids, and amides using SmI2-water-amine reagents, in which we compare the reactivity of three functional groups. The mechanism has been studied using the following: (i) kinetic, (ii) reactivity, (iii) radical clock, and (iv) isotopic labeling experiments. The kinetic data indicate that for the three functional groups all reaction components (SmI2, amine, water) are involved in the rate equation and that the rate of electron transfer is facilitated by base assisted deprotonation of water. Notably, the mechanistic details presented herein indicate that complexation between SmI2, water, and amines can result in a new class of structurally diverse, thermodynamically powerful reductants for efficient electron transfer to a variety of carboxylic acid derivatives. These observations will have important implications for the design and optimization of new processes involving Sm(II)-reduction of ketyl radicals. (Chemical Equation Presented).
- Szostak, Michal,Spain, Malcolm,Eberhart, Andrew J.,Procter, David J.
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p. 11988 - 12003
(2015/01/16)
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- Esters as acylating reagent in a Friedel-Crafts reaction: Indium tribromide catalyzed acylation of arenes using dimethylchlorosilane
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(Chemical Equation Presented) The Friedel-Crafts acylation of arenes with esters by dimethylchlorosilane and 10 mol % of indium tribromide has been achieved. The key intermediate RCOOSi(Cl)Me2 is generated from alkoxy esters with the evolution of the corresponding alkanes. The scope of the alkoxy ester moiety was wide: tert-butyl, benzyl, allyl, and isopropyl esters were successful. In addition, we demonstrated the direct synthesis of the indanone intermediate 11 of salviasperanol from ester 10.
- Nishimoto, Yoshihiro,Babu, Srinivasarao Arulananda,Yasuda, Makoto,Baba, Akio
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supporting information; experimental part
p. 9465 - 9468
(2009/04/06)
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- An oxidative transformation of N′-phenylhydrazide to t-butyl ester using a copper(II) halide-lithium t-butoxide system
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Reactions of hydrazides or N1-phenylhydrazides with a copper(II) reagent prepared from copper(II) bromide and lithium t-butoxide smoothly proceeded to give the corresponding t-butyl ester in high yield.
- Yamaguchi, Jun-Ichi,Aoyagi, Takashi,Fujikura, Ryohei,Suyama, Takayuki
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p. 466 - 467
(2007/10/03)
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- Ligand exchange reaction of sulfoxides in organic synthesis: A versatile procedure for one-carbon homologation of methylesters to esters, thioesters, carboxylic acids and amides
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A novel two-step procedure for one-carbon homologation of methylesters to esters, thioesters, carboxylic acids and amides is described. Methylesters are reacted with lithium carbanion of chloromethyl phenyl sulfoxide to give α-chloro α-sulfinyl ketones in 70 to 90% yields. Potassium enolate of the α-chloro α-sulfinyl ketone was treated with tert-butyllithium at -78°C to give alkynolate via alkylidene carbenoid. This intermediate was treated with alcohols, thioles, 5% aqueous NaOH, and amine hydrochlorides to afford one-carbon homologated esters, thioesters, carboxylic acids and amides, respectively, in good to excellent yields.
- Satoh, Tsuyoshi,Unno, Hideaki,Mizu, Yasuhiro,Hayashi, Yasumasa
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p. 7843 - 7854
(2007/10/03)
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- An Improved and Convenient Synthesis of Esters Using 1,1'-Carbonyldiimidazole and a Reactive Halide
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The esterification of carboxylic acid proceeded easily in a one-pot reaction with 1,1'-carbonyldiimidazole in the presence of a reactive halide under neutral reaction conditions in high yields. Keywords - esterification: 1,1'-carbonyldiimidazole; formylation; tert-butyl ester; imidazolium salt; one-pot reaction
- Kamijo, Tetsuhide,Harada, Hiromu,Iizuka, Kinji
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p. 5044 - 5047
(2007/10/02)
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