- Osmium-Promoted Transformation of Alkyl Nitriles to Secondary Aliphatic Amines: Scope and Mechanism
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The transformation of alkyl nitriles to symmetrical and asymmetrical secondary aliphatic amines promoted by the hexahydride complex OsH6(PiPr3)2 (1) is described, and the mechanisms of the reactions involved are established. Complex 1 catalyzes the aforementioned transformations of aryl-, pyridyl-, and alkoxy-functionalized alkyl nitriles with linear or branched chains. The formation of the secondary amines involves primary imines, primary amines, and secondary imines as organic intermediates. The reactions take place under mild conditions (toluene, 100 °C, and 4 bar of H2). Stoichiometric reactions of 1 with pivalonitrile and 2-methoxyacetonitrile have allowed us to isolate the trihydride azavinylidene derivatives OsH3{═N═CHR}(PiPr3)2 (R = tBu (3), CH2OMe (4)). Their formation involves the insertion of the N-C triple bond of the substrates into an Os-H bond of the unsaturated tetrahydride OsH4(PiPr3)2 (A), which is generated by reductive elimination of H2 from the hexahydride precursor. The reaction of these trihydride azavinylidene species with H2 is the key step for the reduction of the N-C triple bond of the nitriles. In the absence of H2, the attack of A to the azavinylidene ligand produces the rupture of its C(sp2)-C(sp3) bond. As a consequence of this attack and the presence of primary imines and amines in the reaction media, the binuclear complexes (PiPr3)2H4Os(μ-CN)OsH3{κ1-N-(NH═CHCH2OMe)}(PiPr3)2 (5) and (PiPr3)2H4Os(μ-CN)OsH3{κ1-N-(NH2CH2CH2OMe)}(PiPr3)2 (6) have been isolated and characterized by X-ray diffraction analysis, for 2-methoxyacetonitrile. DFT calculations reveal noticeable similarities between the hydrogenations of nitriles to primary imines and those of primary imines to primary amines.
- Babón, Juan C.,Esteruelas, Miguel A.,López, Ana M.,O?ate, Enrique
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supporting information
p. 2177 - 2188
(2020/06/08)
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- Direct Preparation of Amides from Amine Hydrochloride Salts and Orthoesters: A Synthetic and Mechanistic Perspective
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The conversion of a wide range of primary and secondary aliphatic and a few arylamine hydrochloride salts to their corresponding acetamides with trimethyl orthoacetate is described. Mechanistic studies using NMR and gas chromatography-mass spectrometry techniques indicate these reactions proceed via an O-methylimidate intermediate that undergoes in situ demethylation by chloride, affording the corresponding acetamides. Synthetically, this reaction represents a practical, high-yielding protocol with a simple workup for the rapid conversion of amine hydrochloride salts to acetamides.
- Di Grandi, Martin J.,Bennett, Caitlin,Cagino, Kristen,Muccini, Arnold,Suraci, Corey,Saba, Shahrokh
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supporting information
p. 2601 - 2607
(2015/11/28)
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- A DIRECT REDUCTIVE DEAMINATION OF AMIDINES WITH SODIUM BOROHYDRIDE. FORMATION OF DEAMINATED COMPOUNDS AND SECONDARY AMINES
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The reaction of 3-substituted-4-amino-1H-1,5-benzodiazepines (1a, b) with sodium borohydride afforded deaminated compounds (4a, b and 6a, b).On the other hand, acyclic amidines were converted by treatment with sodium borohydride to the corresponding secondary amines (13) under the same conditions.Keywords: 1,5-benzodiazepines; deamination; amidines; mass analysis; IR; absorption of cyano group; N-NMR; 13C-NMR
- Okamoto, Yoshihisa,Kinoshita, Toshio
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p. 1165 - 1169
(2007/10/02)
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- Oxidation hair dyes based upon tetraaminopyrimidine developers
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An aqueous hair dye preparation comprising an oxidation dyestuff combination of a coupling component and a developer component consisting of a tetraaminopyrimidine derivative or a water-soluble acid addition salt thereof, as well as a process for dyeing h
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- Substituted alkylaryl ketones and methods of use as herbicides
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Ring and side chain substituted alkylaryl ketones are useful in controlling the growth of germinating and seedling weed grasses and germinating and seedling broadleaf weeds.
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