- Methyl-Selective α-Oxygenation of Tertiary Amines to Formamides by Employing Copper/Moderately Hindered Nitroxyl Radical (DMN-AZADO or 1-Me-AZADO)
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Methyl-selective α-oxygenation of tertiary amines is a highly attractive approach for synthesizing formamides while preserving the amine substrate skeletons. Therefore, the development of efficient catalysts that can advance regioselective α-oxygenation at the N-methyl positions using molecular oxygen (O2) as the terminal oxidant is an important subject. In this study, we successfully developed a highly regioselective and efficient aerobic methyl-selective α-oxygenation of tertiary amines by employing a Cu/nitroxyl radical catalyst system. The use of moderately hindered nitroxyl radicals, such as 1,5-dimethyl-9-azanoradamantane N-oxyl (DMN-AZADO) and 1-methyl-2-azaadamanane N-oxyl (1-Me-AZADO), was very important to promote the oxygenation effectively mainly because these N-oxyls have longer life-times than less hindered N-oxyls. Various types of tertiary N-methylamines were selectively converted to the corresponding formamides. A plausible reaction mechanism is also discussed on the basis of experimental evidence, together with DFT calculations. The high regioselectivity of this catalyst system stems from steric restriction of the amine-N-oxyl interactions.
- Nakai, Satoru,Yatabe, Takafumi,Suzuki, Kosuke,Sasano, Yusuke,Iwabuchi, Yoshiharu,Hasegawa, Jun-ya,Mizuno, Noritaka,Yamaguchi, Kazuya
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supporting information
p. 16651 - 16659
(2019/11/11)
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- Iron-catalyzed oxyfunctionalization of aliphatic amines at remote benzylic C-H sites
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We report the development of an iron-catalyzed method for the selective oxyfunctionalization of benzylic C(sp3)-H bonds in aliphatic amine substrates. This transformation is selective for benzylic C-H bonds that are remote (i.e., at least three carbons) from the amine functional group. High site selectivity is achieved by in situ protonation of the amine with trifluoroacetic acid, which deactivates more traditionally reactive C-H sites that are α to nitrogen. The scope and synthetic utility of this method are demonstrated via the synthesis and derivatization of a variety of amine-containing, biologically active molecules.
- Mbofana, Curren T.,Chong, Eugene,Lawniczak, James,Sanford, Melanie S.
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supporting information
p. 4258 - 4261
(2016/09/09)
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- A novel traceless solid phase tertiary amine synthesis based on Merrifield resin
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Substitution of Merrifield resin by a secondary amine gives a resin-bound tertiary amine which is then quaternised with an alkyl halide to provide a resin-bound quaternary ammonium salt. Cleavage of the ammonium salt with morpholine delivers a tertiary am
- Cai, Jiaqiang,Wathey, Bernard
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p. 1383 - 1385
(2007/10/03)
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- A new route to dithiocarbamates from tertiary N-methyl and N-benzylamines
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The sequential treatment of various tertiary N-methyl and N-benzylamines with carbon disulfide, and then with an alkyl halide in tetrahydrofuran gave the corresponding dithiocarbamates in good to excellent yields.
- Pujol,Guillaumet
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p. 1231 - 1238
(2007/10/02)
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- Ketanserin Analogues: Structure-Affinity Relationships for 5-HT2 and 5-HT1C Serotonin Receptor Binding
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Ketanserin is the prototypic 5-HT2 serotonin antagonist; although it has been an important tool for the study of serotonin pharmacology, it has had relatively little impact on drug design because remarkably little is known about its structure-affinity relationships.Furthermore, ketanserin also binds at 5-HT1C receptors and even less is known about the influence of its structural features on 5-HT1C receptor affinity.The present study reveals that the fluoro and carbonyl groups of the 4-fluorobenzoyl portion of ketanserin make small contributions to 5-HT2 binding and that the intact benzoylpiperidine moiety is an important feature.Ring opening of the piperidine ring reduces affinity.Although the quinazoline-2,4-dione moiety also contributes to binding, it appears to play a smaller role and can be structurally simplified with retention of 5-HT2 affinity.N-(4-Phenylbutyl)-4-(4-fluorobenzoyl)piperidine (39), for example, binds with nearly tha same affinity (Ki=5.3 nM) as ketanserin (Ki=3.5 nM).All of the compounds examined bind at 5-HT1C sites with lower affinity than ketanserin, and some of the simplified analogues bind with nearly 10 times the 5-HT2 versus 5-HT1C selectivity of ketanserin; however, none displays > 120 fold selectivity.Several of the compounds, such as the amide 32 and the urea 33 represent examples of new structural classes of 5-HT2 ligands.
- Herndon, Jeff L.,Ismaiel, Abd,Ingher, Stacy P.,Teitler, M.,Glennon, Richard A.
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p. 4903 - 4910
(2007/10/02)
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- Mercuric acetate cyclization of 4-(arylmethyl)piperidines: Synthesis of indolo[2,3-g]morphans (tetracyclic ring system of strychnos indole alkaloids) and 7,8-benzomorphans
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A new synthetic route to indolo[2,3-g]morphans and 7,8-benzomorphans is reported. The key step in these syntheses is the mercuric acetate oxidation of appropriate 2-(4-piperidyl-methyl)indoles or 4-benzylpiperidines, respectively. An alternative synthetic
- Bosch,Bonjoch,Diez,et al.
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p. 1753 - 1762
(2007/10/02)
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