- Ruthenium catalyzed β-selective alkylation of vinylpyridines with aldehydes/ketonesviaN2H4mediated deoxygenative couplings
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Umpolung (polarity reversal) tactics of aldehydes/ketones have greatly broadened carbonyl chemistry by enabling transformations with electrophilic reagents and deoxygenative functionalizations. Herein, we report the first ruthenium-catalyzed β-selective alkylation of vinylpyridines with both naturally abundant aromatic and aliphatic aldehyde/ketonesviaN2H4mediated deoxygenative couplings. Compared with one-electron umpolung of carbonyls to alcohols, this two-electron umpolung strategy realized reductive deoxygenation targets, which were not only applicable to the regioselective alkylation of a broad range of 2/4-alkene substituted pyridines, but also amenable to challenging 3-vinyl and steric-embedded internal pyridines as well as their analogous heterocyclic structures.
- Lv, Leiyang,Li, Chao-Jun
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p. 2870 - 2875
(2021/03/14)
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- Palladium-Catalyzed Defluorinative Alkylation of gem-Difluorocyclopropanes: Switching Regioselectivity via Simple Hydrazones
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Conventional approaches for Pd-catalyzed ring-opening cross-couplings of gem-difluorocyclopropanes with nucleophiles predominantly deliver the β-fluoroalkene scaffolds (linear selectivity). Herein, we report a cooperative strategy that can completely switch the reaction selectivity to give the alkylated α-fluoroalkene skeletons (branched selectivity). The unique reactivity of hydrazones that enables analogous inner-sphere 3,3′-reductive elimination driven by denitrogenation, as well as the assistance of steric-embedded N-heterocyclic carbene ligand, are the key to switch the regioselectivity. A wide range of hydrazones derived from naturally abundant aryl and alkyl aldehydes are well applicable, and various gem-difluorocyclopropanes, including modified pharmaceutical and biological molecules, can be efficiently functionalized with high value alkylated α-fluorinated alkene motifs under mild conditions.
- Lv, Leiyang,Li, Chao-Jun
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supporting information
p. 13098 - 13104
(2021/05/03)
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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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- Synergistic Relay Reactions To Achieve Redox-Neutral α-Alkylations of Olefinic Alcohols with Ruthenium(II) Catalysis
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Herein, we report a ruthenium-catalyzed redox-neutral α-alkylation of unsaturated alcohols based on a synergistic relay process involving olefin isomerization (chain walking) and umpolung hydrazone addition, which takes advantage of the interaction between the two rather inefficient individual reaction steps to enable an efficient overall process. This transformation shows the compatibility of hydrazone-type “carbanions” and active protons in a one-pot reaction, and at the same time achieves the first Grignard-type nucleophilic addition using olefinic alcohols as latent carbonyl groups, providing a higher yield of the corresponding secondary alcohol than the classical hydrazone addition to aldehydes does. A broad scope of unsaturated alcohols and hydrazones, including some complex structures, can be successfully employed in this reaction, which shows the versatility of this approach and its suitability as an alternative, efficient means for the generation of secondary and tertiary alcohols.
- Kan, Jian,Li, Chao-Jun,Li, Chen-Chen,Li, Jianbin,Lv, Leiyang,Qiu, Zihang
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supporting information
p. 4544 - 4549
(2020/02/04)
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- Switch in Selectivity for Formal Hydroalkylation of 1,3-Dienes and Enynes with Simple Hydrazones
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Controlling reaction selectivity is a permanent pursuit for chemists. Regioselective catalysis, which exploits and/or overcomes innate steric and electronic bias to deliver diverse regio-enriched products from the same starting materials, represents a powerful tool for divergent synthesis. Recently, the 1,2-Markovnikov hydroalkylation of 1,3-dienes with simple hydrazones was reported to generate branched allylic compounds when a nickel catalyst was used. As part of the effort, shown here is that a complete switch of Markovnikov to anti-Markovnikov addition is obtained by changing to a ruthenium catalyst, thus providing direct and efficient access to homoallylic products exclusively. Isotopic substitution experiments indicate that no reversible hydro-metallation across the metal-π-allyl system occurred under ruthenium catalysis. Moreover, this protocol is applicable to the regiospecific hydroalkylation of the distal C=C bond of 1,3-enynes.
- Li, Chao-Jun,Lv, Leiyang,Qiu, Zihang,Yu, Lin
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supporting information
p. 6466 - 6472
(2020/03/13)
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- Palladium-Catalyzed Formal Hydroalkylation of Aryl-Substituted Alkynes with Hydrazones
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We have developed an unprecedented Pd-catalyzed formal hydroalkylation of alkynes with hydrazones, which are generated in situ from naturally abundant aldehydes, as both alkylation reagents and hydrogen donors. The hydroalkylation proceeds with high regio- and stereoselectivity to form (Z)-alkenes, which are more difficult to generate compared to (E)-alkenes. The reaction is compatible with a wide range of functional groups, including hydroxy, ester, ketone, nitrile, boronic ester, amine, and halide groups. Furthermore, late-stage modifications of natural products and pharmaceutical derivatives exemplify its unique chemoselectivity, regioselectivity, and synthetic applicability. Mechanistic studies indicate the possible involvement of Pd-hydride intermediates.
- Yu, Lin,Lv, Leiyang,Qiu, Zihang,Chen, Zhangpei,Tan, Ze,Liang, Yu-Feng,Li, Chao-Jun
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supporting information
p. 14009 - 14013
(2020/06/10)
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- Palladium-catalyzed hydroalkylation of methylenecyclopropanes with simple hydrazones
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A palladium-catalyzed hydroalkylation reaction of methylenecyclopropanes via highly selective C-C σ-bond scission was achieved under mild conditions, in which simple hydrazones served as carbanion equivalents. This method featured good functional group compatibility, affording high yields of C-alkylated terminal alkenes.
- Cao, Dawei,Chen, Zhangpei,Li, Chao-Jun,Lv, Leiyang,Yao, Jinzhong,Yu, Lin
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p. 10759 - 10763
(2020/10/26)
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- Nickel-catalyzed cross-coupling of umpolung carbonyls and alkyl halides
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An effective nickel-catalyzed cross-coupling of Umpolung carbonyls and alkyl halides was developed. Complementary to classical alkylation techniques, this reaction utilizes Umpolung carbonyls as the environmentally benign alkyl nucleophiles, providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Qiu, Zihang,Li, Chao-Jun
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- Nickel-Catalyzed Cross-Coupling of Umpolung Carbonyls and Alkyl Halides
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An effective nickel-catalyzed cross-coupling of Umpolung carbonyls and alkyl halides was developed. Complementary to classical alkylation techniques, this reaction utilizes Umpolung carbonyls as the environmentally benign alkyl nucleophiles, providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Qiu, Zihang,Li, Chao-Jun
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p. 6312 - 6322
(2019/05/24)
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- Denitrogenative Hydrotrifluoromethylation of Benzaldehyde Hydrazones: Synthesis of (2,2,2-Trifluoroethyl)arenes
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Reacting hydrazones of arylaldehydes with Togni's CF3-benziodoxolone reagent, in the presence of potassium hydroxide and cesium fluoride, induces a denitrogenative hydrotrifluoromethylation event to produce (2,2,2-trifluoroethyl)arenes. This novel reaction was tolerant to many electronically-diverse functional groups and substitution patterns, as well as naphthyl- and heteroaryl-derived substrates. Advantages of this process include the easy access to hydrazone precursors on a large scale, speed and operational simplicity, and being transition metal-free.
- Zhao, Zhensheng,Ma, Kevin C. Y.,Legault, Claude Y.,Murphy, Graham K.
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supporting information
p. 11240 - 11245
(2019/08/20)
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- Umpolung cross-coupling of polyfluoroarenes with hydrazones: Via activation of C-F bonds
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An umpolung strategy for the cross-coupling of polyfluoroarenes with various substituted hydrazones to construct C(sp2)-C(sp3) bonds is developed. In this strategy, the C-F bond of polyfluoroarenes is cleaved and coupled with moisture- and air-stable hydrazones under mild conditions with good to excellent yields. This method provides a useful tool for synthesizing polyfluorinated pharmaceuticals and functional materials.
- Cao, Dawei,Pan, Pan,Zeng, Huiying,Li, Chao-Jun
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supporting information
p. 9323 - 9326
(2019/08/08)
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- Nickel-Catalyzed Regioselective Hydrobenzylation of 1,3-Dienes with Hydrazones
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Hydroalkylation of unsaturated hydrocarbons with unstabilized carbon nucleophiles is difficult and remains a major challenge. The disclosed examples so far have mainly focused on the involvement of heteroatom and/or stabilized carbon nucleophiles as efficient reaction partners. Reported here is an unprecedented regioselective nickel-catalyzed hydrobenzylation of 1,3-dienes with hydrazones, generated in situ from abundant aryl aldehydes and ketones and acting as both the sources of unstabilized carbanion equivalent and hydride. With this strategy, both terminal and sterically hindered internal dienes are hydroalkylated efficiently in a highly selective manner, thus providing a reliable catalytic method to construct challenging C(sp3)-C(sp3) bonds.
- Lv, Leiyang,Zhu, Dianhu,Qiu, Zihang,Li, Jianbin,Li, Chao-Jun
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p. 9199 - 9205
(2019/10/14)
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- Fluorescent molecule, preparation method thereof, application thereof and fluorescence detection reagent (by machine translation)
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The invention discloses a fluorescent molecule, a preparation method thereof, an application thereof and a fluorescence detection reagent. A fluorescent molecule, which is a compound having the structure represented (1) by the following formula: wherein the compound is (1) as follows. In-flight vehicle R1 Alkyl group or substituted aromatic group and R group thereof2 A substituted aromatic group containing a-N&S * FF1D;N-N&S * FF1D;CH-group. -Né N-N&S * FF1D; N-N&S * FF1D; CH-group can specifically interact with hypochlorous acid, so that it can have naked eye recognition capability on hypochlorous acid, and simultaneously, the hypochlorite ion can be accurately, sensitively, specifically and efficiently detected. (by machine translation)
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Paragraph 0143; 0149
(2019/12/02)
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- Nickel-catalyzed cross-coupling of aldehydes with aryl halides: Via hydrazone intermediates
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Traditional cross-couplings require stoichiometric organometallic reagents. A novel nickel-catalyzed cross-coupling reaction between aldehydes and aryl halides via hydrazone intermediates has been developed, merging the Wolff-Kishner reduction and the classical cross-coupling reactions. Aromatic aldehydes, aryl iodides and aryl bromides are especially effective in this new cross-coupling chemistry.
- Tang, Jianting,Lv, Leiyang,Dai, Xi-Jie,Li, Chen-Chen,Li, Lu,Li, Chao-Jun
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supporting information
p. 1750 - 1753
(2018/02/21)
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- Cross-Coupling of Phenol Derivatives with Umpolung Aldehydes Catalyzed by Nickel
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A nickel-catalyzed cross-coupling to construct the C(sp2)-C(sp3) bond was developed from two sustainable biomass-based feedstocks: phenol derivatives with umpolung aldehydes. This strategy features the in situ generation of moisture/air-stable hydrazones from naturally abundant aldehydes, which act as alkyl nucleophiles under catalysis to couple with readily available phenol derivatives. The avoidance of using both halides as the electrophiles and organometallic or organoboron reagents (also derived from halides) as the nucleophiles makes this method more sustainable. Water tolerance, great functional group (ketone, ester, free amine, amide, etc.) compatibility, and late-stage elaboration of complex biological molecules exemplified its practicability and unique chemoselectivity over organometallic reagents.
- Lv, Leiyang,Zhu, Dianhu,Tang, Jianting,Qiu, Zihang,Li, Chen-Chen,Gao, Jian,Li, Chao-Jun
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p. 4622 - 4627
(2018/05/22)
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- Umpolung of Carbonyl Groups as Alkyl Organometallic Reagent Surrogates for Palladium-Catalyzed Allylic Alkylation
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Palladium-catalyzed allylic alkylation of nonstabilized carbon nucleophiles is difficult and remains a major challenge. Reported here is a highly chemo- and regioselective direct palladium-catalyzed C-allylation of hydrazones, generated from carbonyls, as a source of umpolung unstabilized alkyl carbanions and surrogates of alkyl organometallic reagents. Contrary to classical allylation techniques, this umpolung reaction utilizes hydrazones prepared not only from aryl aldehydes but also from alkyl aldehydes and ketones as renewable feedstocks. This strategy complements the palladium-catalyzed coupling of unstabilized nucleophiles with allylic electrophiles by providing an efficient and selective catalytic alternative to the traditional use of highly reactive alkyl organometallic reagents.
- Zhu, Dianhu,Lv, Leiyang,Li, Chen-Chen,Ung, Sosthene,Gao, Jian,Li, Chao-Jun
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supporting information
p. 16520 - 16524
(2018/11/23)
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- Synthesis of 1H-indazole: A combination of experimental and theoretical studies
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A new practical synthesis of 1H-indazole is presented. A previous mechanism for the cyclization step is proved to be nonfeasible and a hydrogen bond propelled mechanism is proposed. The new mechanism is suitable for similar cyclization, and a new reaction is predicted. Springer Science+Business Media B.V. 2012.
- Chen, Xinzhi,Zhou, Shaodong,Qian, Chao,He, Chaohong
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p. 1619 - 1628
(2012/10/30)
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- A novel approach to fluoro-containing alkenes
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A new and general one-pot transformation of aromatic aldehydes to fluorinated olefins containing -CH=C(Cl)CF3 or -CH=C(F)CClF2 moieties is described. Freons CCl3CF3 and CCl2FCClF2 were used as trifluoromethyl and difluoromethyl C2-building blocks respectively. A proposed mechanism for the reaction is discussed.
- Korotchenko, Vasily N,Shastin, Alexey V,Nenajdenko, Valentine G,Balenkova, Elisabeth S
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p. 7519 - 7527
(2007/10/03)
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