- Tropylium-promoted Ritter reactions
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The Ritter reaction used to be one of the most powerful synthetic tools to functionalize alcohols and nitriles, providing valuableN-alkyl amide products. However, this reaction has not been frequently used in modern organic synthesis due to its employment of strongly acidic and harsh reaction conditions, which often lead to complicated side reactions. Herein, we report the development of a new method using salts of the tropylium ion to promote the Ritter reaction. This method works well on a range of alcohol and nitrile substrates, giving the corresponding products in good to excellent yields. This reaction protocol is amenable to microwave and continuous flow reactors, offering an attractive opportunity for further applications in organic synthesis.
- Doan, Son H.,Hussein, Mohanad A.,Nguyen, Thanh Vinh
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supporting information
p. 8901 - 8904
(2021/09/10)
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- Cobalt-Mediated Decarboxylative/Desilylative C?H Activation/Annulation Reaction: An Efficient Approach to Natural Alkaloids and New Structural Analogues
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A Co(II)-mediated decarboxylative/desilylative C?H activation/annulation reaction for the efficient synthesis of 3-arylisoquinolines has been developed. Using alkynyl carboxylic acid and alkynyl silane as terminal alkyne precursors, providing straightforw
- Hai, Li,Lai, Ruizhi,Lv, Shan,Nie, Ruifang,Wu, Yong,Yang, Zhongzhen,chen, Kang
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supporting information
(2022/02/03)
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- Cobalt-Catalyzed, Directed C-H Functionalization/Annulation of Phenylglycinol Derivatives with Alkynes
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A new method for cobalt-catalyzed C(sp2)-H functionalization of phenylglycinol derivatives with terminal and internal alkynes directed by picolinamide auxiliary has been developed. This method offers an efficient and highly regioselective route for the synthesis of 1-hydroxymethyltetrahydroisoquinolines. The reaction employs commercially available Co(II) catalyst in the presence of Mn(III) cooxidant and oxygen as a terminal oxidant and proceeds with full preservation of original stereochemistry.
- Bolsakova, Jekaterina,Lukasevics, Lukass,Grigorjeva, Liene
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p. 4482 - 4499
(2020/04/09)
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- Oxidative C-H/N-H Annulation of Aromatic Amides with Dialkyl Malonates: Access to Isoindolinones and Dihydrobenzoindoles
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A copper-mediated oxidative C-H/N-H annulation of aromatic amides with dialkyl malonates has been presented to afford synthetically valuable dihydrobenzoindoles and isoindolinones. The reaction proceeds through direct oxidative C(sp2)-H/C(sp3)-H coupling followed by an intramolecular N-H/C(sp3)-H dehydrogenative coupling to deliver the target motifs with broad scope and functional group tolerance.
- Pradhan, Sourav,Roy, Subhasish,Banerjee, Sonbidya,De, Pinaki Bhusan,Punniyamurthy, Tharmalingam
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p. 5741 - 5749
(2020/05/19)
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- Highly chemoselective, sterically sensitive NHC-catalysed amine acylation with pyridil
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A new strategy for the protection of amines has been developed involving reaction with pyridil under the influence of N-heterocyclic carbene catalysis. The methodology is capable of distinguishing between two amines characterised by small differences in steric bulk and the resulting pyridoyl amides can be cleaved without requiring either strongly acidic or basic hydrolysis.
- Maguire, Amy C.,Kumar, Vikas,Connon, Stephen J.
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supporting information
p. 13526 - 13529
(2019/11/14)
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- Cobalt-Catalyzed ortho-C?H Functionalization/Alkyne Annulation of Benzylamine Derivatives: Access to Dihydroisoquinolines
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A practical picolinamide-directed C?H functionalization/alkyne annulation of benzylamine derivatives enabling access to the previously elusive 1,4-dihydroisoquinoline skeleton was developed using molecular O2 as the sole oxidant and Co(OAc)2 as precatalyst. The method is compatible with both internal and terminal alkynes and shows high versatility and functional-group tolerance. Furthermore, full preservation of enantiopurity is observed when using non-racemic α-substituted benzylamine derivatives. Kinetic analysis of the reagents and catalyst, labeling experiments, and the isolation and identification of catalytically competent Co-complexes revealed important insights about the mechanism.
- Martínez, ángel Manu,Rodríguez, Nuria,Gómez-Arrayás, Ramón,Carretero, Juan C.
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supporting information
p. 11669 - 11676
(2017/08/30)
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- Cobalt-Catalyzed Selective Synthesis of Isoquinolines Using Picolinamide as a Traceless Directing Group
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Picolinamide has first been employed as a traceless directing group for the cobalt-catalyzed oxidative annulation of benzylamides with alkynes to synthesize isoquinolines through C-H/N-H bonds activation. Oxygen is used as a terminal oxidant. This protocol exhibits good functional group tolerance and excellent regioselectivity. Both terminal and internal alkynes can be efficiently applied to this catalytic system as substrates.
- Kuai, Changsheng,Wang, Lianhui,Li, Bobin,Yang, Zhenhui,Cui, Xiuling
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supporting information
p. 2102 - 2105
(2017/04/27)
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- Co(II)-Catalyzed Regioselective Cross-Dehydrogenative Coupling of Aryl C-H Bonds with Carboxylic Acids
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A cobalt(II)-catalyzed regioselective aryl C-H bond oxygenation between arenes and aryl or aliphatic carboxylic acids under bidendate-chelation assistance is developed. This method provides an efficient approach to acyoxy-substituted arenes with a broad range of functional group tolerance. Furthermore, this reaction system could be further applied to the preparation of polyfunctional naphthylenes.
- Lan, Jianyong,Xie, Haisheng,Lu, Xiaoxia,Deng, Yuanfu,Jiang, Huanfeng,Zeng, Wei
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supporting information
p. 4279 - 4282
(2017/08/23)
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- Iron-Catalyzed Directed C(sp2)-H and C(sp3)-H Functionalization with Trimethylaluminum
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Conversion of a C(sp2)-H or C(sp3)-H bond to the corresponding C-Me bond can be achieved by using AlMe3 or its air-stable diamine complex in the presence of catalytic amounts of an inorganic iron(III) salt and a diphosphine along with 2,3-dichlorobutane as a stoichiometric oxidant. The reaction is applicable to a variety of amide substrates bearing a picolinoyl or 8-aminoquinolyl directing group, enabling methylation of a variety of (hetero)aryl, alkenyl, and alkyl amides. The use of the mild aluminum reagent prevents undesired reduction of iron and allows the reaction to proceed with catalyst turnover numbers as high as 6500.
- Shang, Rui,Ilies, Laurean,Nakamura, Eiichi
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supporting information
p. 7660 - 7663
(2015/06/30)
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- Cobalt-catalyzed, aminoquinoline-directed C(sp2)-H bond alkenylation by alkynes
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A method for cobalt-catalyzed, aminoquinoline- and picolinamide-directed C(sp2)-H bond alkenylation by alkynes was developed. The method shows excellent functional-group tolerance and both internal and terminal alkynes are competent substrates for the coupling. The reaction employs a Co(OAc)2·4 H2O catalyst, Mn(OAc)2 co-catalyst, and oxygen (from air) as a terminal oxidant.
- Grigorjeva, Liene,Daugulis, Olafs
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p. 10209 - 10212
(2015/03/31)
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- Scope and limitations of auxiliary-assisted, palladium-catalyzed arylation and alkylation of sp2 and sp3 C-H bonds
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The scope of palladium-catalyzed, auxiliary-assisted direct arylation and alkylation of sp2 and sp3 C-H bonds of amine and carboxylic acid derivatives has been investigated. The method employs a palladium acetate catalyst, substrate, aryl, alkyl, benzyl, or allyl halide, and inorganic base in tert-amyl alcohol or water solvent at 100-140 C. Aryl and alkyl iodides as well as benzyl and allyl bromides are competent reagents in this transformation. The picolinic acid auxiliary is used for amine γ-functionalization, and the 8-aminoquinoline auxiliary is used for carboxylic acid β-functionalization. Some optimization of base, additives, and solvent is required for achieving best results.
- Nadres, Enrico T.,Santos, Gerson Ivan Franco,Shabashov, Dmitry,Daugulis, Olafs
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p. 9689 - 9714
(2013/10/22)
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- Copper-promoted sulfenylation of sp2 C-H bonds
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An auxiliary-assisted, copper catalyzed or promoted sulfenylation of benzoic acid derivative β-C-H bonds and benzylamine derivative γ-C-H bonds has been developed. The method employs disulfide reagents, copper(II) acetate, and DMSO solvent at 90-130 °C. Application of this methodology to the direct trifluoromethylsulfenylation of C-H bonds was demonstrated.
- Tran, Ly Dieu,Popov, Ilya,Daugulis, Olafs
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supporting information
p. 18237 - 18240,4
(2020/10/15)
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- Iodine-catalyzed one-pot synthesis of amides from nitriles via Ritter reaction
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Ritter reactions of alcohols and tert-butyl acetate with various nitriles were performed using iodine as a mild and effective catalyst under heating conditions to afford the corresponding amides in good to excellent yields.
- Theerthagiri, Palani,Lalitha, Appaswami,Arunachalam, Pirama Nayagam
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supporting information; experimental part
p. 2813 - 2819
(2010/07/04)
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- Highly efficient method for the synthesis of carboxamides from carboxylic acids and amines using pyridine-3-sulfonyl chloride (3-PSC)
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The use of pyridine-3-sulfonyl chloride (3-PSC) in dehydrating condensation was investigated. This novel reagent was successfully employed as a mild dehydrating reagent for preparing various carboxamides in good to excellent yields from the corresponding carboxylic acids and amines. Copyright
- Funasaka, Setsuo,Kato, Koji,Mukaiyama, Teruaki
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p. 506 - 507
(2008/09/21)
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- Highly efficient method for the synthesis of carboxamides from carboxylic acids and amines using benzenesulfonic anhydride (BSA)
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A highly efficient method by using benzenesulfonic anhydride (BSA) in the presence of 4-(dimethylamino)pyridine (DMAP) to synthesize carboxamides from various carboxylic acids and amines including sterically hindered ones is established. This reaction proceeds smoothly to provide the desired product in high yield. Copyright
- Funasaka, Setsuo,Kato, Koji,Mukaiyama, Teruaki
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p. 1456 - 1457
(2008/03/14)
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- APPLICATIONS of ORGANOLITHIUM and RELATED REAGENTS in SYNTHESIS. Part V. Directed Metallation of Secondary Picolin- and Isonicotinamides. A Useful Method for the Synthesis of 2,3- and 3,4-Disubstituted Pyridines, Including Furopyridin-3(1H)-one and Furopyridine-1(3H)-one
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The metallation reaction of N-methyl-, N-benzyl- and N-phenyl-amides (1a-c) and (2a-c) derived from picolinic and isonicotinic acids by BunLi in THF leading to the corresponding bis(N- and 3-)lithiated amides (3a-c) and (4a-c), are described.The N-phenylamides (anilides) (1c) and (2c), in comparison with the other aliphatic derivatives, demonstrate greater abilities to direct ortho lithiation at the 3-position of the pyridine ring, and give with very good yields bis(N- and 3-)lithiated anilides (3c) and (4c), respectively.The N-benzylamides (1b) and (2b) are ortho metallated under kinetic control at -78 deg C to form the bis(N- and 3-)lithiated benzylamides (3b) and (4b), but the organometallic intermediates rearrange at room temperature to give the thermodynamically more stable bis(N- and α-)lithiated amides (3g) and (4g) (benzyl-type anions).The generated carbanions (3c), (4c), (3g) and (4g) were trapped by a variety of electrophiles (e.g. alkyl halides and aldehydes).The synthesis of furopyridin-3(1H)-one (18) and furopyridin-(3H)-one (19) is included.
- Epsztajn, Jan,Bieniek, Adam,Plotka, Mieczyslaw W.
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p. 442 - 474
(2007/10/02)
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