The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Martin H G Prechtl - One of the best experts on this subject based on the ideXlab platform.
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tuneable hydrogenation of nitriles into Imines or amines with a ruthenium pincer complex under mild conditions
ChemInform, 2015Co-Authors: Jonghoo Choi, Martin H G PrechtlAbstract:By adjustment of the reaction parameters an efficient transformation of aromatic and aliphatic nitriles into amines or Imines is achieved.
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tuneable hydrogenation of nitriles into Imines or amines with a ruthenium pincer complex under mild conditions
Chemcatchem, 2015Co-Authors: Jonghoo Choi, Martin H G PrechtlAbstract:The selective hydrogenation of aromatic and aliphatic nitriles into amines and Imines is described. Using a ruthenium pincer complex, the selectivity towards amines or Imines can be controlled by simple parameter changes. The reactions are conducted under very mild conditions between 50–100 °C at 0.4 MPa H2 pressure without any additives at low catalytic loadings of 0.5–1 mol %, which results in quantitative conversions and high selectivity.
Kourosch Abbaspour Tehrani - One of the best experts on this subject based on the ideXlab platform.
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lewis acid mediated vinyl transfer reaction of alkynes to n alkylImines by using the n alkyl residue as a sacrificial hydrogen donor
ChemInform, 2014Co-Authors: Chandi C Malakar, Sara Stas, Wouter Herrebout, Kourosch Abbaspour TehraniAbstract:A wide variety of allylic amines from Imines and alkynes are synthesized by using In(O-Tf)3 as Lewis acid.
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lewis acid mediated vinyl transfer reaction of alkynes to n alkylImines by using the n alkyl residue as a sacrificial hydrogen donor
Chemistry: A European Journal, 2013Co-Authors: Chandi C Malakar, Sara Stas, Wouter Herrebout, Kourosch Abbaspour TehraniAbstract:A variety of N-alkyl-α,α-dichloroaldImines were vinylated by terminal acetylenes in the presence of Lewis acids such as In(OTf)3 or BF3 ⋅OEt2 and hexafluoroisopropanol (HFIP) as an additive. The reaction proceeds at ambient temperature and leads to geometrically pure allylic β,β-dichloroamines. This approach is complementary to previously reported transition-metal-catalyzed vinyl-transfer methods, which are not applicable to aliphatic Imines and are restricted to Imines that contain an electron-withdrawing nitrogen substituent. In the present approach, terminal alkynes were used as a source of the vinyl residue, and the N-alkyl moiety of the imine acts as a sacrificial hydrogen donor. The additional advantage of this methodology is the fact that no external toxic or hazardous reducing agents or molecular hydrogen has to be used. This new methodology nicely combines a C(sp(2) )C(sp) bond formation, hydride transfer, and an unusual cleavage of an unactivated CN bond, thereby giving rise to functionalized primary allylic amines. A detailed experimental study supported by DFT calculations of the mechanism has been done.
Jincai Zhao - One of the best experts on this subject based on the ideXlab platform.
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selective aerobic oxidation of amines to Imines by tio2 photocatalysis in water
Chemical Communications, 2013Co-Authors: Xianjun Lang, Chuncheng Chen, Jincai ZhaoAbstract:Selective oxidation of benzylic amines to Imines with atmospheric O2 is achieved in water on TiO2 under UV irradiation. The afforded imine could be easily separated and TiO2 can be recycled by filtration. To scale up, gram-scale imine products can be obtained.
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visible light induced selective photocatalytic aerobic oxidation of amines into Imines on tio2
Chemistry: A European Journal, 2012Co-Authors: Xianjun Lang, Yubao Zhao, Chuncheng Chen, Hongwei Ji, Jincai ZhaoAbstract:Imines are important intermediates for the synthesis of fine chemicals, pharmaceuticals, and agricultural chemicals. Selective oxidation of amines into their corresponding Imines with dioxygen is one of the most-fundamental chemical transformations. Herein, we report the oxidation of a series of benzylic amines into their corresponding Imines with atmospheric dioxygen as the oxidant on a surface of anatase TiO2 under visible-light irradiation (λ>420 nm). The visible-light response of this system was caused by the formation of a surface complex through the adsorption of a benzylic amine onto the surface of TiO2. From the analysis of products of specially designed benzylic amines, we demonstrated that a highly selective oxygenation reaction proceeds via an oxygen-transfer mechanism to afford the corresponding carbonyl compound, whose further condensation with an amine would generate the final imine product. We found that when primary benzylic amines (13 examples), were chosen as the substrates, moderate to excellent selectivities for the imine products were achieved (ca. 38–94 %) in moderate to excellent conversion rates (ca. 44–95 %). When secondary benzylic amines (15 examples) were chosen as the substrates, both the corresponding Imines and aldehydes were detected as the main products with moderate to high conversion rates (ca. 18–100 %) and lower selectivities for the imine products (ca. 14–69 %). When tribenzylamine was chosen as the substrate, imine (27 %), dibenzylamine (24 %), and benzaldehyde products (39 %) were obtained in a conversion of 50 %. This report can be viewed as a prototypical system for the activation of CH bonds adjacent to heteroatoms such as N, O, and S atoms, and oxofuctionalization with air or dioxygen as the terminal oxidant under visible-light irradiation using TiO2 as the photocatalyst.
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selective formation of Imines by aerobic photocatalytic oxidation of amines on tio2
ChemInform, 2011Co-Authors: Xianjun Lang, Chuncheng Chen, Jincai ZhaoAbstract:The process involves a highly selective formation of aldehydes, whose further condensation with unreacted or in situ generated amines affords the corresponding Imines.
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selective formation of Imines by aerobic photocatalytic oxidation of amines on tio2
Angewandte Chemie, 2011Co-Authors: Xianjun Lang, Chuncheng Chen, Jincai ZhaoAbstract:Imine derivatives are important building blocks for the synthesis of fine chemicals and pharmaceuticals. Generally, their synthesis involves condensation of an amine and a carbonyl compound. To circumvent the problem caused by the excessively active nature of ketones or aldehydes, an alternative strategy for the direct oxidation of amines has attracted much interest. Dioxygen, or more preferably dioxygen in the air, embodies the quintessential oxidant for chemical synthesis. Unfortunately, the reactivity of dioxygen is difficult to control; it typically reacts under harsh conditions with poor selectivity. Recently, much attention has been paid to organic synthesis photocatalyzed by TiO2. [3] In H2O, the selectivity of TiO2 photocatalysis is especially poor, so that, it is efficient in the degradation of organic pollutants. Even when the reactions are performed in inert organic solvent to prevent generation of OH radicals, the selectivity is usually very low owing to the unselective autooxidation of the photogenerated radicals. However, it has been shown that high selectivity can be realized in the TiO2 photocatalytic system when both generation of the OH radical and unselective autooxidation are avoided. By using O-labeling experiments, our research group has discovered that an oxygen-atom transfer dominates the photocatalytic transformation of alcohols into the corresponding carbonyl compounds on TiO2 in benzotrifluoride. This transformation has a different mechanism than that of noble-metal/transition-metal complex catalysis. All the experimental results support a mechanism as shown in Equation (1). Such a mechanism avoids the unselective autooxidation processes, which commonly occur in TiO2 photocatalysis in the presence of dioxygen, and hence should lead to high selectivity in the photocatalytic oxidation of alcohols. This mechanistic insight can direct us to envision new reactions. Herein, we report our findings on a series of benzylic amines that were selectively transformed into the corresponding Imines using 1 atm of air as the oxidant by TiO2 photocatalysis in acetonitrile. The formation of Imines involves a two-step process: a selective oxygenation step to generate the aldehydes and a subsequent condensation step to afford the Imines. The high selectivity for the formation of Imines is attributed to both the highly selective formation of aldehydes from amines [Eq. (2)] via a similar mechanism to
Keiji Tanino - One of the best experts on this subject based on the ideXlab platform.
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synthesis of aryl amine derivatives from benzyl nitriles via electrocyclization of in situ generated n silyl ketene Imines
Organic Letters, 2016Co-Authors: Fumihiko Yoshimura, Taiki Abe, Keiji TaninoAbstract:The previously unexplored reactivity of N-silyl ketene Imines in organic synthesis is reported. Benzyl nitriles containing an alkenyl or aryl group at the ortho position were smoothly converted into aryl amines in good yields under two sets of mild silylation conditions: (1) nonbasic conditions using TMSNTf2–iPr2NEt or (2) basic anionic conditions using lithium diisopropylamide–triisopropylsilyl chloride (LDA–TIPSCl). The reaction probably proceeds via in situ generation of an N-silyl ketene imine followed by 6π-electrocyclization and aromatization.
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Synthesis of Aryl Amine Derivatives from Benzyl Nitriles via Electrocyclization of in Situ Generated N‑Silyl Ketene Imines
2016Co-Authors: Fumihiko Yoshimura, Taiki Abe, Keiji TaninoAbstract:The previously unexplored reactivity of N-silyl ketene Imines in organic synthesis is reported. Benzyl nitriles containing an alkenyl or aryl group at the ortho position were smoothly converted into aryl amines in good yields under two sets of mild silylation conditions: (1) nonbasic conditions using TMSNTf2–iPr2NEt or (2) basic anionic conditions using lithium diisopropylamide–triisopropylsilyl chloride (LDA–TIPSCl). The reaction probably proceeds via in situ generation of an N-silyl ketene imine followed by 6π-electrocyclization and aromatization
Jonghoo Choi - One of the best experts on this subject based on the ideXlab platform.
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tuneable hydrogenation of nitriles into Imines or amines with a ruthenium pincer complex under mild conditions
ChemInform, 2015Co-Authors: Jonghoo Choi, Martin H G PrechtlAbstract:By adjustment of the reaction parameters an efficient transformation of aromatic and aliphatic nitriles into amines or Imines is achieved.
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tuneable hydrogenation of nitriles into Imines or amines with a ruthenium pincer complex under mild conditions
Chemcatchem, 2015Co-Authors: Jonghoo Choi, Martin H G PrechtlAbstract:The selective hydrogenation of aromatic and aliphatic nitriles into amines and Imines is described. Using a ruthenium pincer complex, the selectivity towards amines or Imines can be controlled by simple parameter changes. The reactions are conducted under very mild conditions between 50–100 °C at 0.4 MPa H2 pressure without any additives at low catalytic loadings of 0.5–1 mol %, which results in quantitative conversions and high selectivity.