- Base-Mediated Borylsilylation/Silylation of Ammonium Salts with Silylborane
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This work describes a base-mediated borylsilylation of benzylic ammonium salts to synthesize geminal silylboronates bearing benzylic proton under mild reaction conditions. Deaminative silylation of aryl ammonium salts was also achieved in the presence of
- Du, Xian,Guan, Yun-Shi,Li, Yi-Hui,Liang, Guohai,Luo, Yong,Qi, Wan-Ying,Wang, Zi-Ying,Wei, Xun,Xu, Xiao-Hong,Yuan, Han,Zhen, Jing-Song
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supporting information
p. 5988 - 5992
(2021/08/31)
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- Fluoxetine scaffold to design tandem molecular antioxidants and green catalysts
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Fluoxetine finds application in the treatment of depression and mood disorders. This selective serotonin-reuptake inhibitor (SSRI) also contrasts oxidative stress by direct ROS scavenging, modulation of the endogenous antioxidant defense system, and/or enhancement of the serotonin antioxidant capacity. We synthesised some fluoxetine analogues incorporating a selenium nucleus, thus expanding its antioxidant potential by enabling a hydroperoxides-inactivating, glutathione peroxidase (GPx)-like activity. Radical scavenging and peroxidatic activity were combined in a water-soluble, drug-like, tandem antioxidant molecule. Selenofluoxetine derivatives were reacted with H2O2in water, and the mechanistic details of the reaction were unravelled combining nuclear magnetic resonance (NMR), electrospray ionisation-mass spectrometry (ESI-MS) and quantum chemistry calculations. The observed oxidation-elimination process led to the formation of seleninic acid and cinnamylamine in atrans-selective manner. This mechanism is likely to be extended to other substrates for the preparation of unsaturated cinnamylamines.
- Bortoli, Marco,Gianoncelli, Alessandra,Ongaro, Alberto,Orian, Laura,Oselladore, Erika,Ribaudo, Giovanni,Zagotto, Giuseppe
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p. 18583 - 18593
(2020/06/08)
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- Platinum-catalyzed direct amination of allylic alcohols under mild conditions: Ligand and microwave effects, substrate scope, and mechanistic study
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Transition metal-catalyzed amination of allylic compounds via a π-allylmetal intermediate is a powerful and useful method for synthesizing allylamines. Direct catalytic substitution of allylic alcohols, which forms water as the sole coproduct, has recently attracted attention for its environmental and economical advantages. Here, we describe the development of a versatile direct catalytic amination of both aryl- and alkyl-substituted allylic alcohols with various amines using Pt-Xantphos and Pt-DPEphos catalyst systems, which allows for the selective synthesis of various monoallylamines, such as the biologically active compounds Naftifine and Flunarizine, in good to high yield without need for an activator. The choice of the ligand was crucial toward achieving high catalytic activity, and we demonstrated that not only the large bite-angle but also the linker oxygen atom of the Xantphos and DPEphos ligands was highly important. In addition, microwave heating dramatically affected the catalyst activity and considerably decreased the reaction time compared with conventional heating. Furthermore, several mechanistic investigations, including 1H and 31P{1H} NMR studies; isolation and characterization of several catalytic intermediates, Pt(xantphos)Cl2, Pt(η2-C3H5OH)(xantphos), etc; confirmation of the structure of [Pt(η3-allyl)(xantphos)]OTf by X-ray crystallographic analysis; and crossover experiments, suggested that formation of the π-allylplatinum complex through the elimination of water is an irreversible rate-determining step and that the other processes in the catalytic cycle are reversible, even at room temperature.
- Ohshima, Takashi,Miyamoto, Yoshiki,Ipposhi, Junji,Nakahara, Yasuhito,Utsunomiya, Masaru,Mashima, Kazushi
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body text
p. 14317 - 14328
(2010/02/16)
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- Hydride Transfer Reaction Products in the Aminomethylation of Styrene
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Aminomethylation of styrene with formaldehyde and dimethylamine leads to N-methylbenzenepropanamine (1), N-(3-phenylpropyl)benzenepropanamine (3), and α-methylenebenzenepropanal (4) as major products.The ratio of 1, 3 and 4 is considerably influenced by the ratio of the reactants.The best yield of 1 is obtained by using dimethylamine in excess.Styrene in excess favors the formation of 3, and equivalent amounts of reactants afford the best yield of 4.Using formaldehyde in excess leads to the complete N-methylation of 1 and 3.When styrene reacts with formaldehyde and diethylamine or diisopropylamine the most important aminomethylation products are N-ethylbenzenepropanamine (11) or N-isopropylbenzenepropanamine (12), respectively, and 3 and 4 in both cases.The formation of the major products in the aminomethylation of styrene can be explained by the hydride transfer mechanism represented earlier as one competing mechanism for the aminomethylation of certain bicyclic alkenes.The N-methylation of amine 1 and 3, when formaldehyde is used in excess, is due to Eschweiler methylation under aminomethylation conditions.
- Manninen, Kalle,Karjalainen, Aira
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p. 190 - 195
(2007/10/02)
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- Base Catalysed Rearrangements involving Ylide Intermediates. Part 16. The Preparation and Thermal Rearrangement of Allylammonioamidates
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The ammonioamidates (7) and (11) undergo rearrangement (R3=CH2Ph) and competing and rearrangements (R3=allyl).The rates of the and rearrangements of the cinnamyl ammonioamidates (11a), (11b), (11d), and (11g) show similar dependence on the nature of the substituent X.The rate of the rearrangement of the reaction products (14b), (14d), and (14g) is relatively insensitive to substituent effects, suggesting that the rates of ammonioamidate rearrangements are largely controlled by conjugation between the group X and the N(-)CO system.The and rearrangements of the cinnamylammonioamidate (11d) show moderate and similar dependence upon solvent polarity suggesting that the transition state for both reactions has considerable dipolar character.The apparent intramolecularity of the and rearrangements of the cinnamylammonioamidate (11e) as estimated by isotopic mixing methods is decreased by isotopic scrambling in the ylide due to radical recombination to give ylide (11l) in addition to products (13l) and (14l).If allowance is made for this effect the rearrangement appears to be largely, or even entirely, intramolecular and the rearrangement shows intermolecularity comparable with that found for the rearrangements of analogous ammonium ylides under similar reaction conditions.
- Chantrapromma, Kan,Ollis, W. David,Sutherland, Ian O.
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p. 1029 - 1039
(2007/10/02)
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- Competing Hydride Transfer and Ene Reactions in the Aminoalkylation of 1-Alkenes with N,N-Dimethylmethyleniminium Ions. A Literature Correction
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A literature report that N,N-dimethylmethyleniminium ion (2) reacts with propylene and styrene to form unsaturated tertiary amines is shown to be incorrect.The major products are the secondary amines 1-(methylamino)butane and 1-(methylamino)-3-phenylpropane in which N-demethylation has occurred along with the saturation of the alkene.Analogous major products are formed with 1-butene, 1-hexene, 1-octene, 1-dodecene, 1-tetradecene, p-methylstyrene, and m-nitrostyrene as substrates.When the substrates are isobutylene, 2-ethyl-1-hexene, α-methylstyrene, and p-methoxystyrene, the major products are tertiary amines, but the secondary amines are also formed in smaller yields.The small yields of tertiary amines obtained in the cases of styrene and p-methylstyrene were increased by going from solvent acetic acid to acetonitrile and by increasing the branching of the alkyl groups on nitrogen.The internal olefins 5-decene and cyclohexene were far less reactive, giving only 3-4percent of amine products that were mainly tertiary in the former case and secondary in the latter.It is concluded that tertiary amine products are favored by an alkene structure and a solvent that favors the formation of a stable carbenium ion intermediate or a transition state with substantial carbenium ion character upon electrophilic attack of the iminium ion on the alkene.The secondary amine products are favored when a carbenium ion is of low stability and when the β-carbon atom of the olefin and/or the alkyl group attached to nitrogen is sterically unhindered; such hindrance decreases the rate of hydride ion transfer that is believed to occur in the production of secondary amines.
- Cohen, Theodore,Onopchenko, Anatoli
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p. 4531 - 4537
(2007/10/02)
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- INVESTIGATIONS IN THE FIELD OF AMINES AND AMMONIUM COMPOUNDS. CLV. STEVENS REARRANGEMENT WITH THE PARTICIPATION OF A METHYL-SUBSTITUTED ALKOXYCARBONYLMETHYL GROUP
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Under the influence of sodium methoxide in ether ammonium salts containing a methyl-substituted alkoxycarbonylmethyl group together with a group of the allylic type undergo a Stevens rearrangement with the formation of the esters of substituted 2-dimethylamino-4-pentenoic acids.The susceptibility to thermal isomerisation in the products from rearrangement of salts containing a γ-phenylallyl or γ,γ-dimethylallyl group as migrating group increases greatly if there is a methyl or allyl substituent in the methoxycarbonylmethyl group.
- Kocharyan, S. T.,Grigoryan, V. V.,Voskanyan, V. S.,Panosyan, G. A.,Babayan, A. T.
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p. 1619 - 1622
(2007/10/02)
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- Base Catalysed Rearrangements involving Ylide Intermediates. Part 1. The Rearrangements of Diallyl- and Allylpropynyl-ammonium Cations
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The base catalysed rearrangements of diallylammonium cations and allylpropynylammonium cations are described.In most cases, the major product arises by a symmetry-allowed sigmatropic rearrangement of the intermediate ylide.The minor products can be regarded as being derived by homolysis of the ylide into a radical pair followed by recombination.
- Jemison, Robert W.,Laird, Trevor,Ollis, W. David,Sutherland, Ian O.
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p. 1436 - 1449
(2007/10/02)
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