- Metal-Free Stereoselective Synthesis of (E)- And (Z)-N-Monosubstituted β-Aminoacrylates via Condensation Reactions of Carbamates
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N-monosubstituted β-aminoacrylates are building blocks, which have been used in the preparation of amino acids and pharmaceuticals. Two efficient, stereoselective methods of preparation, via acid- or base-promoted condensation reactions of carbamates, are described. The base-promoted reaction is E-selective, while acid catalysis can, through the choice of solvent, selectively form E or Z. The acid-catalyzed E-selective process proceeds through a crystallization obviating the need for chromatographic purification.
- Dion, Amélie,Pollack, Scott R.
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p. 11748 - 11762
(2021/09/07)
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- NOVEL AMIDATION METHOD
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The present invention relates to a novel amidation process. To the present invention, an active N -center radical activated by light irradiation can be utilized to provide a selective amidation method. In addition, the present invention can provide an amide compound derived from an aldehyde having a functional group of various aspects, and is expected to be applicable to various technical fields.
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Paragraph 0096-0103
(2021/09/21)
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- Controlled Relay Process to Access N-Centered Radicals for Catalyst-free Amidation of Aldehydes under Visible Light
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Nitrogen-centered radicals have attracted increasing attention as a versatile reactive intermediate for diverse C–N bond constructions. Despite the significant advances achieved in this realm, the controllable formation of such species under catalyst-free conditions remains highly challenging. Here, we report a new relay process involving the slow in situ generation of a photoactive N-chloro species via C–N bond formation, which subsequently enables mild and selective access to N-centered radicals under visible light conditions. The utility of this approach is demonstrated by the conversion of aldehydes to amides, employing N-chloro-N-sodio carbamates as a practical amidating source. This synthetic operation obviates the need for catalysts, external oxidants, and coupling reagents that are typically required in related processes, consequently allowing high functional group tolerance and excellent applicability for late-stage functionalization. Amides are an important class of structural motifs prevalently found in bioactive compounds and synthetic materials of great significance. Amidation of aldehydes has been established as an atom-efficient strategy for amide synthesis; however, current methods lack in applicability mainly due to the requirement of troublesome reagents. In this article, we describe an unconventional relay process to convert aldehydes to amides under catalyst-, oxidant-, and coupling-reagent-free conditions, which is enabled by the development of a new mechanistic platform that gives efficient and controllable access to N-centered radicals under visible light. A wide range of (hetero)aromatic and aliphatic aldehydes can be employed, including those derived from biologically relevant complex molecules. We anticipate that the accomplished methodological advances, combined with the unique mechanistic features, will lead to the widespread application of the present strategy in broad research fields. A catalyst-free approach for controlled access to N-centered radicals is described, which enables the conversion of aldehydes to amides via an unconventional relay process harnessing visible light. The key tactic relies on the use of photostable N-chloro-N-sodio-carbamate amidating reagent that leads to slow incorporations of a photoactive radical source via C–N formation and other involved intermediates thereafter. This methodology displays excellent applicability and sustainable chemistry credentials and, thus, holds a promise for finding broad applications.
- Chang, Sukbok,Jeon, Hyun Ji,Jung, Hoimin,Kim, Dongwook,Lee, Wongyu,Seo, Sangwon
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supporting information
p. 495 - 508
(2021/01/28)
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- N-Chloro- N-sodio-carbamates as a Practical Amidating Reagent for Scalable and Sustainable Amidation of Aldehydes under Visible Light
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Herein, we describe the scalability and sustainability investigations toward the visible light-mediated amidation of aldehydes with N-chloro-N-sodio-carbamates. The practicality credentials of N-chloro-N-sodio-carbamates for their use in multigram scale a
- Jeon, Hyun Ji,Lee, Wongyu,Seo, Sangwon,Chang, Sukbok
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supporting information
p. 1176 - 1183
(2021/05/31)
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- Decarboxylative Oxygenation via Photoredox Catalysis
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The direct conversion of aliphatic carboxylic acids to their dehomologated carbonyl analogues has been accomplished through photocatalytic decarboxylative oxygenation. This transformation is applicable to an array of carboxylic acid motifs, producing ketones, aldehydes, and amides in excellent yields. Preliminary results demonstrate that this methodology is further amenable to aldehyde substrates via in situ oxidation to the corresponding acid and subsequent decarboxylative oxygenation. We have exploited this strategy for the sequential oxidative dehomologation of linear aliphatic chains.
- Faraggi, Tomer M.,Li, Wei,MacMillan, David W. C.
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p. 410 - 415
(2019/12/24)
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- A General Method for Photocatalytic Decarboxylative Hydroxylation of Carboxylic Acids
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A general and practical method for decarboxylative hydroxylation of carboxylic acids was developed through visible light-induced photocatalysis using molecular oxygen as the green oxidant. The addition of NaBH4 to in situ reduce the unstable peroxyl radical intermediate much broadened the substrate scope. Different sp3 carbon-bearing carboxylic acids were successfully employed as substrates, including phenylacetic acid-type substrates, as well as aliphatic carboxylic acids. This transformation worked smoothly on primary, secondary, and tertiary carboxylic acids.
- Khan, Shah Nawaz,Zaman, Muhammad Kashif,Li, Ruining,Sun, Zhankui
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p. 5019 - 5026
(2020/05/01)
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- Reversible Twisting of Primary Amides via Ground State N-C(O) Destabilization: Highly Twisted Rotationally Inverted Acyclic Amides
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Since the seminal studies by Pauling in 1930s, planarity has become the defining characteristic of the amide bond. Planarity of amides has central implications for the reactivity and chemical properties of amides of relevance to a range of chemical disciplines. While the vast majority of amides are planar, nonplanarity has a profound effect on the properties of the amide bond, with the most common method to restrict the amide bond relying on the incorporation of the amide function into a rigid cyclic ring system. In a major departure from this concept, here, we report the first class of acyclic twisted amides that can be prepared, reversibly, from common primary amides in a single, operationally trivial step. Di-tert-butoxycarbonylation of the amide nitrogen atom yields twisted amides in which the amide bond exhibits nearly perpendicular twist. Full structural characterization of a range of electronically diverse compounds from this new class of twisted amides is reported. Through reactivity studies we demonstrate unusual properties of the amide bond, wherein selective cleavage of the amide bond can be achieved by a judicious choice of the reaction conditions. Through computational studies we evaluate structural and energetic details pertaining to the amide bond deformation. The ability to selectively twist common primary amides, in a reversible manner, has important implications for the design and application of the amide bond nonplanarity in structural chemistry, biochemistry and organic synthesis.
- Meng, Guangrong,Shi, Shicheng,Lalancette, Roger,Szostak, Roman,Szostak, Michal
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supporting information
p. 727 - 734
(2018/01/26)
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- Formation of Amides from Imines via Cyanide-Mediated Metal-Free Aerobic Oxidation
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A new protocol for the direct formation of amides from imines derived from aromatic aldehydes via metal-free aerobic oxidation in the presence of cyanide is described. This protocol was applicable to various aldimines, and the desired amides were obtained in moderate to good yields. Mechanistic studies suggested that this aerobic oxidative amidation might proceed via the addition of cyanide to imines followed by proton transfer from carbon to nitrogen in the original imines, leading to carbanions of α-amino nitriles, which undergo subsequent oxidation with molecular oxygen in air to provide the desired amide compounds.
- Seo, Hong-Ahn,Cho, Yeon-Ho,Lee, Ye-Sol,Cheon, Cheol-Hong
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p. 11993 - 11998
(2016/01/09)
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- Development of Method for Amide Bond Formation via Metal-Free Aerobic Oxidative Amination of Aldehydes
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The present invention relates to a method for preparing an amide compound by using an aerobic oxidative amination reaction using an oxygen resource as an oxidizer in an organic solvent without metal by using a cyanide as a catalyst. An expensive metal catalyst is not needed to prepare the amide compound of the present invention. Therefore, the amide compound does not have a problem of toxicity caused by remaining metal and has excellent economic efficiency of atoms. Moreover, the amide compound can be used for industries in an easy manner because complicated processes such as a strong acid, low temperatures, and anhydrous conditions are not needed to prepare the amide compound.COPYRIGHT KIPO 2015
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Paragraph 0094; 0140; 0414
(2016/11/17)
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- 2-Chloroanthraquinone-catalyzed aerobic photo-oxidative synthesis of diacylamines from benzylamides
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In this Letter, we report the aerobic photo-oxidative synthesis of diacylamines from benzylamides in the presence of molecular oxygen and catalytic amounts of 2-chloroanthraquinones under visible light irradiation from a fluorescent lamp.
- Itoh, Izuho,Matsusaki, Yoko,Fujiya, Akitoshi,Tada, Norihiro,Miura, Tsuyoshi,Itoh, Akichika
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p. 3160 - 3162
(2014/05/20)
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- Asymmetric auto-tandem catalysis with a planar-chiral ruthenium complex: Sequential allylic amidation and atom-transfer radical cyclization
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Ru does it all: A novel example of an asymmetric auto-tandem reaction catalyzed by a planar-chiral cyclopentadienyl-ruthenium complex is described. The reaction of allylic chloride with α-haloamides provides synthetically useful, diastereomerically and enantiomerically enriched γ-lactams with multiple stereogenic centers through one-pot sequential allylic amidation/atom-transfer radical cyclization. PG=protecting group. Copyright
- Kanbayashi, Naoya,Takenaka, Kazuhiro,Okamura, Taka-Aki,Onitsuka, Kiyotaka
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p. 4897 - 4901
(2013/06/05)
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- Metal-free synthesis of imido derivatives by direct oxidation of α-amido sulfones
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Oxidation of α-amidoaryl sulfones with m-chloroperoxybenzoic acid under mild conditions readily provides the corresponding imides in satisfactory yields. The overall processprobably involves formation of an N-acyliminium ion intermediate, which by attack
- Martinelli, Fabio,Palmieri, Alessandro,Petrini, Marino
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experimental part
p. 5085 - 5089
(2010/10/21)
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- Phenylsilane as an active amidation reagent for the preparation of carboxamides and peptides
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The use of phenylsilane as a mild coupling reagent for amidation reactions is reported. Applicability to both solution- and solid-phase chemistry has been demonstrated for a variety of amines and carboxylic acids.
- Ruan, Zheming,Lawrence, R. Michael,Cooper, Christopher B.
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p. 7649 - 7651
(2007/10/03)
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- A reversible safety-catch method for the hydrogenolysis of N-benzyl moieties
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The benzyl groups of β-hydroxy-N-benzyl sulfonamides are labile toward hydrogenolysis-unlike N-benzyl sulfonamides lacking the β-hydroxy moiety. We find that N-acyl-N-benzyl sulfonamides undergo hydrogenolysis under very mild conditions. Based upon these observations, we developed a reversible safety-catch method using tert-butoxycarbonyl moieties to activate N-benzyl sulfonamides toward hydrogenolysis. We also explored the utility of the safety-catch activation method for other nitrogen-based functionality such as N-benzyl carboxamides, imides, and related functionality.
- Johnson II, David C.,Widlanski, Theodore S.
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p. 8483 - 8487
(2007/10/03)
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- Acidity of Benzoylcarbamates in Dimethyl Sulfoxide. Confirmation of Mixed N/O Alkylation in the Mitsunobu Reaction
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Seventeen benzoyl-, 4-methoxybenzoyl-, and 4-nitrobenzoyl-carbamates have been synthesized via their corresponding isocyanates and their acidities determined in dimethyl sulfoxide solution.Their pKa values span an interval of nearly 5 pK units
- Koppel, Ilmar,Koppel, Juta,Koppel, Ivar,Leito, Ivo,Pihl, Viljar,et al.
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p. 655 - 658
(2007/10/02)
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- A New Method for the Synthesis of Amides from Amines: Ruthenium Tetroxide Oxidation of N-Protected Alkylamines
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A simple synthetic method for the preparation of amides from the corresponding primary alkylamines was elaborated using ruthenium tetroxide (RuO4) oxidation as a key step.
- Tanaka, Ken-Ichi,Yoshifuji, Shigeyuki,Nitta, Yoshihiro
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p. 3125 - 3129
(2007/10/02)
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- SYNTHESIS AND USE OF BENZYL TERT-BUTYL IMINODICARBONATE, A VERSATILE REAGENT FOR THE PREPARATION OF AMINES
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An efficient synthesis of benzyl tert-butyl iminodicarbonate (IV), starting from benzoyl isocyanate, is reported.Reaction of the isocyanate with benzyl alcohol gave benzyl N-benzoylcarbamate (II) which on exhaustive tert-butoxycarbonylation via the non-isolated triacyl amine III, after aminolysis, provided the title compound.The sodium salt V was alkylated with various halides under Gabriel conditions to give in high yields the corresponding benzyloxycarbonyl tert-butoxycarbonyl diprotected amines.Similarly, compound IV was alkylated with alcohols under Mitsunobu conditions to give some additional amines of this type, from which the protecting groups can be removed selectively under mild conditions.
- Grehn, Leif,Ragnarsson, Ulf
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p. 2778 - 2786
(2007/10/02)
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