- Cobalt-Catalyzed Intermolecular Markovnikov Hydroamination of Nonactivated Olefins: N2-Selective Alkylation of Benzotriazole
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Cobalt-catalyzed Markovnikov-selective hydroamination of nonactivated olefins was developed. Hydrogen atom transfer from a catalytically generated cobalt(III)-hydride complex to the olefins proceeded regioselectively, and the nucleophilic addition of benzotriazoles occurred selectively at their N2-positions. The synthetic utility of the obtained N2-alkylated benzotriazoles as stable amine protecting groups under various reaction conditions was demonstrated, and the products were also transformed into primary amines by zinc-mediated reduction.
- Yahata, Kenzo,Kaneko, Yuki,Akai, Shuji
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p. 598 - 603
(2020/02/04)
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- Cerium-Catalyzed C-H Functionalizations of Alkanes Utilizing Alcohols as Hydrogen Atom Transfer Agents
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Modern photoredox catalysis has traditionally relied upon metal-to-ligand charge-transfer (MLCT) excitation of metal polypyridyl complexes for the utilization of light energy for the activation of organic substrates. Here, we demonstrate the catalytic application of ligand-to-metal charge-transfer (LMCT) excitation of cerium alkoxide complexes for the facile activation of alkanes utilizing abundant and inexpensive cerium trichloride as the catalyst. As demonstrated by cerium-catalyzed C-H amination and the alkylation of hydrocarbons, this reaction manifold has enabled the facile use of abundant alcohols as practical and selective hydrogen atom transfer (HAT) agents via the direct access of energetically challenging alkoxy radicals. Furthermore, the LMCT excitation event has been investigated through a series of spectroscopic experiments, revealing a rapid bond homolysis process and an effective production of alkoxy radicals, collectively ruling out the LMCT/homolysis event as the rate-determining step of this C-H functionalization.
- An, Qing,Chen, Yuegang,Liu, Weimin,Pan, Hui,Wang, Xin,Wang, Ziyu,Zhang, Kaining,Zuo, Zhiwei
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p. 6216 - 6226
(2020/04/27)
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- Potential Synthetic Adaptogens: V. Synthesis of Cage Monoamines by the Schwenk–Papa Reaction
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The reduction of cage ketoximes under Schwenk–Papa reaction conditions was studied to establish that the d,l, d- and l-camphor oximes are smoothly reduced to the corresponding amines in high yields. At the same time, d,l-norcamphor and adamantan-2-one oximes undergo partial catalytic deoximation to form a mixture of the corresponding amines and alcohols.
- Brunilin, R. V.,Mkrtchyan, A. S.,Nawrozkij, M. B.,Novakov, I. A.,Vernigora, A. A.,Voloboev, S. N.,Vostrikova, O. V.
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p. 1742 - 1748
(2020/01/11)
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- Direct Primary Amination of Alkylmetals with NH-Oxaziridine
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A method for the primary electrophilic amination of primary, secondary, and tertiary organometallic substrates from a bench-stable NH-oxaziridine reagent is described. This facile and highly chemoselective transformation occurs at ambient temperature and without transition metal catalysts or purification by column chromatography to provide alkylamine products in a single step. Density functional theory (DFT) calculations revealed that, despite the basicity of alkylmetals, the direct NH-transfer pathway is favored over proton and O-transfer.
- Behnke, Nicole Erin,Kielawa, Russell,Kwon, Doo-Hyun,Ess, Daniel H.,Kürti, László
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supporting information
p. 8064 - 8068
(2019/01/04)
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- Iridium-catalyzed intermolecular hydroamination of unactivated aliphatic alkenes with amides and sulfonamides
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The intermolecular addition of N-H bonds to unactivated alkenes remains a challenging, but desirable, strategy for the synthesis of N-alkylamines. We report the intermolecular amination of unactivated α-olefins and bicycloalkenes with arylamides and sulfonamides to generate synthetically useful protected amine products in high yield. Mechanistic studies on this rare catalytic reaction revealed a resting state that is the product of N-H bond oxidative addition and coordination of the amide. Rapid, reversible dissociation of the amide precedes reaction with the alkene, but an intramolecular, kinetically significant rearrangement of the species occurs before this reaction with alkene.
- Sevov, Christo S.,Zhou, Jianrong,Hartwig, John F.
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supporting information; experimental part
p. 11960 - 11963
(2012/09/08)
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- COMPOSITIONS AND METHODS FOR CYCLOFRUCTANS AS SEPARATION AGENTS
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The present invention relates to derivatized cyclofructan compounds, compositions comprising derivatized cyclofructan compounds, and methods of using compositions comprising derivatized cyclofructan compounds for chromatographic separations of chemical species, including enantiomers. Said compositions may comprise a solid support and/or polymers comprising derivatized cyclofructan compounds.
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Page/Page column 45-49; 63
(2010/12/31)
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- ISOXAZOLES AND THEIR USE IN THE TREATMENT OF ISCHEMIC DISEASES
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The present invention provides a compound of formula I, or a pharmaceutically acceptable salt thereof. These compounds are useful for the treatment of neurological, neurodegenerative, ischemic and inflammatory disorders. Accordingly, the invention also provides pharmaceutically acceptable compositions comprising the compounds of the invention and methods of utilizing those compounds and compositions in the treatment of neurological, neurodegenerative, ischemic and inflammatory disorders.
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- ALKYL AND ARYL ISOTHIOCYANATES AS MASKED PRIMARY AMINES
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Primary and secondary (but not tertiary) alkyl as well as aryl isothiocyanates react rapidly with 4-methyl-1,2-benzenedithiol (1) in methanol at room temperature, releasing the corresponding amines in good yields.This mild and simple procedure for unmasking amines proceeds chemospecifically with isothiocyanates even in the presence of such normally electrophilic and reactive functionalities as carboxylate ester and N-alkylphthalimide.
- Cho, Cheon-Gyu,Posner, Gary H.
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p. 3599 - 3602
(2007/10/02)
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- ORGANOBORANES FOR SYNTHESIS. 7. AN IMPROVED GENERAL SYNTHESIS OF PRIMARY AMINES FROM ALKENES via HYDROBORATION-ORGANOBORANE CHEMISTRY
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Triorganylboranes, R3B, and diorganylborinicesters, R2BOR', react readily with preformed chloramine or hydroxylamine-O-sulfonic acid to produce the corresponding primary amines, RNH2.However, the product of the reaction following hydrolysis is the boronic acid, RB(OH)2, limiting the yield to 67percent for R3B and to 50percent for R2BOR'.This problem has now been overcome with the help of lithium dimethylborohydride, readily converted in situ to dimethylborane.The hydroboration of representative alkenes by dimethylborane provides the corresponding monoorganyldimethylborane, RMe2B.Treatment of this intermediate with hydroxylamine-O-sulfonic acid provides the desired amines, RNH2, in isolated yields of 73percent to 95percent.The reaction proceeds with complete retention, reproducing the precise structure of the organic group in the organoboranes, RMe2B.
- Brown, Herbert C.,Kim, Kee-Won,Srebnik, Morris,Singaram, Bakthan
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p. 4071 - 4078
(2007/10/02)
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- Catalytic Transfer Hydrogenolysis of N-Benzyl Protecting Groups
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The catalytic transfer hydrogenolysis of a number of N-benzyl compounds has been examined.Of the three hydrogen donors studied, ammonium formate and hydrazine hydrate were more effective than sodium hypophosphite.In general, debenzylation of secondary and tertiary benzylamines could be readily accomplished by refluxing the substrate with an excess of the hydrogen donor in alcoholic solvents for a few hours using catalytic amounts of 10percent palladium on carbon.The two N-benzyl heteroaromatic amines studies were stable to the above conditions.
- Adger, B. M.,O'Farrell, C.,Lewis, N. J.,Mitchell, M. B.
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- Reaction of organoboranes with hydrazoic acid
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Organoboranes react with sodium azide in the presence of aqueous acid to yield primary amines. The reaction presumably proceeds via the anionotropic rearrangement of an organoborate complex.
- Kabalka, George W.,Henderson, David A.,Varma, Rajender S.
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p. 1369 - 1370
(2008/10/08)
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- 2-Norbornanediazonium Ions Revisited
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The reactions of 2-norbornanediazonium ions have been reinvestigated with the aid of optically active and deuterium-labeled precursors.Enantiomeric purities were determined by direct VPC methods, and deuterium distributions by 2H NMR spectroscopy.The product pattern is strongly affected by the polarity of the solvent. exo-Diazonium ions 13 in water yield racemic exo alcohol (s,kΔ) of the norbornadiazonium ions.Optically active exo products are typical of nonpolar solvents and originate most probably from assymetric ion pairs.Model studies with optically active bicyclooct-3-en-2-amine (36) provide conclusive evidence that ion-pair colapse may lead to optically active products even in the case of delocalized achiral carbocations.
- Kirmse, Wolfgang,Siegfried, Rainer
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p. 950 - 956
(2007/10/02)
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