- Pathways of the reaction between N,N-disubstituted propargylic amines and cationic zirconium complexes
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The reaction of N-tert-alkyl-substituted propargylic amines with trialkylalanes in the presence of 20 mol.% Cp2ZrCl2 was studied. The pattern of the products depended on the nature of substituents at the nitrogen atom. N-tert-Alkyl-N-arylmethyl-substituted propargylic amines when reacted in CH2Cl2 aff ord a mixture of N-tert-alkyl-N-(arylmethyl)alkylamines and N-tertalkyl-N-(arylmethyl)amines at ratios from {2: 3 to {3: 2 in total yield of 70–95%. In hexane, N-tert-alkyl-N-(arylmethyl)amines are produced selectively. N-Alkyl-N-tert-alkyl-substituted propargylic amines similar to N-isoalkyl-substituted ones underwent a Zr-promoted hydride transfer to aff ord (2E)-alkenylamines in good yield (58–69%).
- Dzhemilev, U. M.,Kadikova, R. N.,Ramazanov, I. R.,Saitova, Z. R.
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Read Online
- Structure-Activity Relationship and Biological Investigation of SR18292 (16), a Suppressor of Glucagon-Induced Glucose Production
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Despite a myriad of available pharmacotherapies for the treatment of type 2 diabetes (T2D), challenges still exist in achieving glycemic control. Several novel glucose-lowering strategies are currently under clinical investigation, highlighting the need f
- Cameron, Michael D.,Griffin, Patrick R.,Kamenecka, Theodore M.,Lin, Hua,Lin, Li,Novick, Scott J.,Puigserver, Pere,Ruiz, Claudia,Sharabi, Kfir,Zhu, Di
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supporting information
p. 980 - 990
(2021/02/01)
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- Heterometallic Mg?Ba Hydride Clusters in Hydrogenation Catalysis
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Reaction of a MgN“2/BaN”2 mixture (N“=N(SiMe3)2) with PhSiH3 gave three unique heterometallic Mg/Ba hydride clusters: Mg5Ba4H11N”7 ? (benzene)2 (1), Mg4Ba7H13N“9 ? (toluene)2 (2) and Mg7Ba12H26N”12 (3). Product formation is controlled by the Mg/Ba ratio and temperature. Crystal structures are described. While 3 is fully insoluble, clusters 1 and 2 retain their structures in aromatic solvents. DFT calculations and AIM analyses indicate highly ionic bonding with Mg?H and Ba?H bond paths. Also unusual H????H? bond paths are observed. Catalytic hydrogenation with MgN“2, BaN”2 and the mixture MgN“2/BaN”2 has been studied. Whereas MgN“2 is only active in imine hydrogenation, alkene and alkyne hydrogenation needs the presence of Ba. The catalytic activity of the MgN”2/BaN“2 mixture lies in general between that of its individual components and strong cooperative effects are not evident.
- Wiesinger, Michael,Knüpfer, Christian,Elsen, Holger,Mai, Jonathan,Langer, Jens,Harder, Sjoerd
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p. 4567 - 4577
(2021/09/09)
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- Regio- and Enantioselective Intramolecular Amide Carbene Insertion into Primary C-H Bonds Using Ru(II)-Pheox Catalyst
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We have established a method for the highly regio- and enantioselective functionalization of tert-butyl groups via intramolecular amide carbene insertion into C-H bonds, yielding γ-lactams with 91% ee in up to 99% yield. This reaction uses a ruthenium(II) phenyl oxazoline (Ru(II)-Pheox) complex. The catalytic intramolecular carbene transfer reaction to the primary C-H bond proceeds rapidly and selectively compared to that with secondary C-H, benzylic secondary C-H, tert-C-H, or sp2C-H bonds in the presence of 1 mol % Ru(II)-Pheox catalyst. This is the first example of a catalytic carbenoid insertion into an unactivated tert-butyl group with enantiocontrol at the carbenoid carbon.
- Nakagawa, Yoko,Chanthamath, Soda,Liang, Yumeng,Shibatomi, Kazutaka,Iwasa, Seiji
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p. 2607 - 2618
(2019/02/26)
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- Electrochemical Approach for Direct C-H Phosphonylation of Unprotected Secondary Amine
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Direct α-phosphonylation of an unprotected secondary amine in a single step is of practical importance to amino phophophates. However, this protocol is limited due to the high redox barrier of unprotected amine. In this paper, we report C-H phosphonylation of an unprotected secondary amine via an electrochemical approach in the presence of catalytic carboxylate salt. This metal-free and exogenous oxidant-free method furnishes diverse target molecules with satisfactory yield under mild reaction conditions. Successful application of the protocol in a gram-scale experiment demonstrates the potential utility for further functionalization.
- Huang, Min,Dai, Jie,Cheng, Xu,Ding, Mengning
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supporting information
p. 7759 - 7762
(2019/10/11)
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- Photocatalyzed cascade Meerwein addition/cyclization of: N -benzylacrylamides toward azaspirocycles
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A visible-light-induced cascade Meerwein addition/cyclization of alkenes involving C-F bond cleavage was developed. This method offers a rapid access to azaspirocyclic cyclohexadienones from N-benzylacrylamides via C-F bond cleavage applying H2O as an external oxygen source, allowing for the incorporation of various aromatic moieties originating from aryldiazonium salts.
- Yuan, Li,Jiang, Sheng-Ming,Li, Zeng-Zeng,Zhu, Yong,Yu, Jian,Li, Lan,Li, Ming-Zhu,Tang, Shi,Sheng, Rui-Rong
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supporting information
p. 2406 - 2410
(2018/04/12)
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- Synthetic method and application of azaspirocyclohexadienone
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The invention discloses a method of synthesizing aryl substituted azaspirocyclohexadienone by aromatizing a visible light induced (N)-benzylacrylamide compound and diazonium salt of fluoboric acid toform a ring. The synthesized target compound has the structure as shown in the formula as described in the specification. A preparation method comprises the following steps: carrying out a reaction bytaking the (N)-benzylacrylamide compound and the diazonium salt as a reaction primer for 18 h, Ru(bpy)3Cl2 as a catalyst, K2CO3 as alkali and DMF (N,N-dimethylformamide) as a solvent in a nitrogen environment, wherein the reaction temperature is room temperature; and carrying out column chromatography or thin-layer chromatographic separation and purification on the product through washing, concentration and the like to obtain the target product azaspirocyclohexadienone. The synthesizing reaction is simple to operate, the adopted free radical source is low in price and easy to obtain, the reaction system is mild and environmentally friendly, and the method is high in selectivity, simple in condition and high in yield, and has a huge popularization and application value.
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Paragraph 0009; 0010
(2018/08/04)
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- LiAlH4: From Stoichiometric Reduction to Imine Hydrogenation Catalysis
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Imine-to-amine conversion with catalytic instead of stoichiometric quantities of LiAlH4 is demonstrated (85 °C, catalyst loading≥2.5 mol %, pressure≥1 bar). The effects of temperature, pressure, solvent, and catalyst modifications, as well as the substrate scope are discussed. Experimental investigations and preliminary DFT calculations suggest that the catalytically active species is generated in situ: LiAlH4+Ph(H)C=NtBu→LiAlH2[N(tBu)CH2Ph]2. A cooperative mechanism in which Li and Al both play a prominent role is proposed.
- Elsen, Holger,F?rber, Christian,Ballmann, Gerd,Harder, Sjoerd
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p. 7156 - 7160
(2018/05/30)
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- Improved Buchner reaction selectivity in the copper-catalyzed reactions of ethyl 3-arylmethylamino-2-diazo-3-oxopropanoates
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Ethyl 3-alkyl(arylmethyl)amino-2-diazo-3-oxopropanoates (diazo amidoacetates) generate generally both cyclohepta[c]pyrrolones (Buchner products) and β-lactams (1,4-insertion products), and show obvious N-substituent-controlled chemoselectivity between the intramolecular Buchner reaction and aliphatic 1,4-C-H insertion under the catalysis of copper salts. The less steric N-alkyl substituents in the amide moiety generally favor the aliphatic 1,4-C-H insertion, while the more steric N-alkyl substituents generally favor the Buchner reaction. Compared with rhodium and ruthenium-catalyzed conditions, the current copper-catalyzed conditions improved the Buchner reaction selectivity of ethyl 3-alkyl(arylmethyl)amino-2-diazo-3-oxopropanoates.
- Liu, Jing,Tu, Jianzhuo,Yang, Zhanhui,Pak, Chol-Ung,Xu, Jiaxi
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p. 4616 - 4626
(2017/07/11)
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- Visible light-induced intramolecular dearomative cyclization of α-bromo-N-benzyl-alkylamides: Efficient construction of 2-azaspiro[4.5]decanes
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An efficient intramolecular dearomative cyclization via visible light-induced photoredox catalysis allows for a highly regioselective dearomative cyclization of α-bromo-N-benzyl-alkylamides to construct 2-azaspiro[4.5]decanes in the presence of an iridium catalyst.
- Hu, Bei,Li, Yuyuan,Dong, Wuheng,Ren, Kai,Xie, Xiaomin,Wan, Jun,Zhang, Zhaoguo
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supporting information
p. 3709 - 3712
(2016/03/05)
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- Structure-Reactivity Relationship in the Frustrated Lewis Pair (FLP)-Catalyzed Hydrogenation of Imines
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The autoinduced, frustrated Lewis pair (FLP)-catalyzed hydrogenation of 16-benzene-ring substituted N-benzylidene-tert-butylamines with B(2,6-F2C6H3)3 and molecular hydrogen was investigated by kinetic analysis. The pKa values for imines and for the corresponding amines were determined by quantum-mechanical methods and provided a direct proportional relationship. The correlation of the two rate constants k1 (simple catalytic cycle) and k2 (autoinduced catalytic cycle) with pKa difference between imine and amine pairs (ΔpKa) or Hammett's σ parameter served as useful parameters to establish a structure-reactivity relationship for the FLP-catalyzed hydrogenation of imines.
- Tussing, Sebastian,Kaupmees, Karl,Paradies, Jan
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supporting information
p. 7422 - 7426
(2016/05/24)
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- Reductive Transformations of Carbonyl Compounds Catalyzed by Rhodium Supported on a Carbon Matrix by using Carbon Monoxide as a Deoxygenative Agent
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An efficient method for the rhodium on carbon matrix catalyzed preparation of secondary and tertiary amines, cyanoesters, and nitriles through the reductive amination/alkylation of carbonyl compounds was developed, including a convenient procedure for the tandem formal reductive addition of acetonitrile to aldehydes. The catalyst could be reused, and at least three consecutive reaction cycles were performed with comparable efficiency. The method was shown to be compatible with functional groups prone to reduction by hydrogen and complex hydrides. Beyond the matrix: An efficient method for the rhodium on carbon matrix catalyzed preparation of secondary and tertiary amines, cyanoesters, and nitriles through the reductive amination/alkylation of carbonyl compounds is developed, including a convenient procedure for the tandem formal reductive addition of acetonitrile to aldehydes. TON=turnover number.
- Yagafarov, Niyaz Z.,Usanov, Dmitry L.,Moskovets, Alexey P.,Kagramanov, Nikolai D.,Maleev, Victor I.,Chusov, Denis
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p. 2590 - 2593
(2015/09/15)
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- Diazo- And transition-metal-free C-H insertion: A direct synthesis of β-lactams
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Carbene intermediates are very useful species for a range of reactions including C-H insertions and cycloadditions. They are most commonly generated by metal-catalyzed release of nitrogen gas from diazo precursors. Herein, we present a novel C-H insertion
- Gomes, Luis F. R.,Veiros, Ls F.,Maulide, Nuno,Afonso, Carlos A. M.
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supporting information
p. 1449 - 1453
(2015/01/30)
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- A robust palladium(II)-Porphyrin complex as catalyst for visible light induced oxidative C-H functionalization
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A series of palladium(II)-porphyrin complexes that display dual emissions with lifetimes up to 437μs have been synthesized. Among the four complexes, PdF20TPP is an efficient and robust catalyst for photoinduced oxidative C-H functionalization by using oxygen as terminal oxidant. α-Functionalized tertiary amines were obtained in good to excellent yields by light irradiation (λ>400nm) of a mixture of PdF20TPP, tertiary amine, and nucleophile (cyanide, nitromethane, dimethyl malonate, diethyl phosphite, and acetone) under aerobic conditions. Four examples of intramolecular cyclized amine compounds could be similarly prepared. Comparison of the UV-visible absorption spectra before and after the photochemical reaction revealed that PdF20TPP was highly robust (>95 % recovery). The practical application of PdF20TPP has been revealed by the photochemical reactions performed by using a low catalyst loading (0.01mol %) and on a 10mmol scale. The PdF20TPP catalyst could sensitize photoinduced oxidation of sulfides to sulfoxides in excellent yields. Mechanistic studies revealed that the photocatalysis proceeded by singlet-oxygen oxidation. Long-lived excited states! A series of palladium(II)-porphyrin complexes have been synthesized and found to display long-lived excited states with lifetimes up to 437μs (see scheme). Among these complexes, PdF 20TPP is an efficient and robust catalyst for a broad array of photoinduced oxidative C-H functionalization reactions. PtF20TPP= platinum(II) meso-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin.
- To, Wai-Pong,Liu, Yungen,Lau, Tai-Chu,Che, Chi-Ming
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p. 5654 - 5664
(2013/06/04)
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- H2 cleavage, hydride formation, and catalytic hydrogenation of imines with zinc complexes of C5Me5 and N-heterocyclic carbenes
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Decamethylzincocene, [ZnCp2], reacts with H2 to give the reduced ZnI compound [Zn2Cp2]. In the presence of coordinating and (more efficiently) of non-coordinating N-heterocyclic carbenes (NHCs), the catalytic hydrogenation of imines with H2 is achieved. The monomeric hydride [Zn(Cp)(H)(SIMes)] is presented and its mechanistic implications are considered. Copyright
- Jochmann, Phillip,Stephan, Douglas W.
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supporting information
p. 9831 - 9835
(2013/09/23)
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- Rapid and efficient access to secondary arylmethylamines
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Ammoniomethyl trifluoroborates are very powerful reagents that can be used to access biologically relevant aryl- and heteroaryl-methylamine motifs via Suzuki-Miyaura cross-couplings. Until now, this method was limited to the production of tertiary and primary amines. The synthesis of a large array of secondary ammoniomethyltrifluoroborates has been achieved through a one step nucleophilic substitution reaction on the potassium bromomethyltrifluoroborate. Smooth cross-coupling conditions have been designed, based on the use of an aminobiphenyl palladium precatalyst, to couple these trifluoroborates efficiently with aryl bromides. This strategy offers a new way to access biologically relevant motifs and allows, with the previously developed methods, access to all three classes of aminomethylarenes. Secondary ammoniomethyltrifluoroborates can be easily synthesized by nucleophilic substitution on potassium bromomethyltrifluoroborate. These reagents have then been used in Suzuki-Miyaura cross-couplings with aryl bromides, offering an effective access to the aminomethylarene structural motif. This new method provides an interesting alternative to the reductive amination procedure (see scheme). Copyright
- Fleury-Brégeot, Nicolas,Raushel, Jessica,Sandrock, Deidre L.,Dreher, Spencer D.,Molander, Gary A.
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supporting information; experimental part
p. 9564 - 9570
(2012/08/28)
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- Luminescent organogold(III) complexes with long-lived triplet excited states for light-induced oxidative C-H bond functionalization and hydrogen production
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All that glitters is gold: Highly phosphorescent gold(III) complexes (see picture) with extended π-conjugated cyclometalating ligands exhibit rich photophysical and photochemical properties. They act as efficient photocatalysts/photosensitizers for oxidative functionalizations of secondary and tertiary benzylic amines and homogeneous hydrogen production from a water/acetonitrile mixture. Copyright
- To, Wai-Pong,Tong, Glenna So-Ming,Lu, Wei,Ma, Chensheng,Liu, Jia,Chow, Andy Lok-Fung,Che, Chi-Ming
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supporting information; body text
p. 2654 - 2657
(2012/04/17)
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- Catalytic hydrogenation with frustrated lewis pairs: Selectivity achieved by size-exclusion design of lewis acids
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Catalytic hydrogenation that utilizes frustrated Lewis pair (FLP) catalysts is a subject of growing interest because such catalysts offer a unique opportunity for the development of transition-metal-free hydrogenations. The aim of our recent efforts is to further increase the functional-group tolerance and chemoselectivity of FLP catalysts by means of size-exclusion catalyst design. Given that hydrogen molecule is the smallest molecule, our modified Lewis acids feature a highly shielded boron center that still allows the cleavage of the hydrogen but avoids undesirable FLP reactivity by simple physical constraint. As a result, greater latitude in substrate scope can be achieved, as exemplified by the chemoselective reduction of α,β-unsaturated imines, ketones, and quinolines. In addition to synthetic aspects, detailed NMR spectroscopic, DFT, and 2H isotopic labeling studies were performed to gain further mechanistic insight into FLP hydrogenation. Copyright
- Eroes, Gabor,Nagy, Krisztina,Mehdi, Hasan,Papai, Imre,Nagy, Peter,Kiraly, Peter,Tarkanyi, Gabor,Soos, Tibor
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scheme or table
p. 574 - 585
(2012/03/08)
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- Expanding the scope of metal-free catalytic hydrogenation through frustrated Lewis pair design
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No metal causes frustration: Based on a conceptual framework, novel frustrated Lewis acid-base catalyst systems with orthogonal reactivity have been developed. Aside from enhanced functional-group tolerance, unique chemoselectivity can be achieved in catalytic metal-free hydrogenations (see scheme).
- Eros, Gabor,Mehdi, Hasan,Papai, Imre,Rokob, Tibor Andras,Kiraly, Peter,Tarkanyi, Gabor,Soos, Tibor
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supporting information; experimental part
p. 6559 - 6563
(2010/10/20)
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- Efficient oxidative radical spirolactamization
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An efficient xanthate-based method for the preparation of azaspirocyclic cyclohexadienones via an ipso oxidative radical cyclization of p-oxygenated N-benzylacetamides and N-phenetylacetamide is described. The Royal Society of Chemistry.
- Ibarra-Rivera, Tannya R.,Gamez-Montano, Rocio,Miranda, Luis D.
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p. 3485 - 3487
(2008/03/12)
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- Ruthenium porphyrin catalyzed intramolecular carbenoid C-H insertion. Stereoselective synthesis of Cis-disubstituted oxygen and nitrogen heterocycles
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(Matrix presented) A ruthenium porphyrin-catalyzed stereoselective intramolecular carbenoid C-H insertion is described. Using [Ru II(TTP)(CO)] as catalyst, aryl tosylhydrazones are converted to 2,3-dihydrobenzofurans, 2,3-dihydroindoles, and β-lactams in good yields and remarkable cis selectivity (up to 99%). Enantioselective synthesis of 2,3-dihydrobenzofurans is also achieved with [RuII(D 4-Por*)(CO)] as catalyst, and up to 96% ee is attained.
- Cheung, Wai-Hung,Zheng, Shi-Long,Yu, Wing-Yiu,Zhou, Guo-Chuan,Che, Chi-Ming
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p. 2535 - 2538
(2007/10/03)
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- Pyrrolidinone-fused cyclohexenones by regioselective dearomatising anionic cyclisation of 2-, 3- or 4-methoxybenzamides
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On treatment with t-BuLi in the presence of HMPA, 2-, 3- or 4-methoxybenzamides (o-, m- or p-anisamides) bearing N-benzyl substituents cyclise with dearomatisation to give methyl dienyl ethers which hydrolyse to give single stereo- and regioisomers of pyr
- Clayden,Tchabanenko,Yasin,Turnbull
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p. 302 - 304
(2007/10/03)
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- Reactions of N-Chlorobenzylalkylamines with Sodium Methoxide in Methanol. Steric Effects in Elimination Reactions
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Reactions of N-chlorobenzylalkylamines in which the alkyl group is Me, Et, i-Pr, t-Bu, and sec-Bu with MeONa-MeOH have been investigated kinetically.The eliminations are quantitative and regiospecific, producing only benzylidenealkylamines.The reactions are first order in base and first order in substrate, and an E2 mechanism is evident.The relative rates of elimination at 25 deg C are 1/0.5/0.3/0.2/0.01 for Me/Et/i-Pr/sec-Bu/t-Bu alkyl substituents, respectively.The results are attributed to repulsive interaction between the alkyl group and the base in the transition state.Hammett ρ and kH/kD values decreased, but the ΔH(excit.) and ΔS(excit.) values increased with bulkier alkyl substituents.Changes in the transition-state parameters with the substrate steric effect are interpreted with variation in structure of the imine-forming transition states.
- Cho, Bong Rae,Maeng, Jun Ho,Yoon, Jong Chan,Kim, Tae Rin
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p. 4752 - 4756
(2007/10/02)
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- A NEW METHOD OF SYNTHESIZING C-ARYL-N-TERT-BUTYLNITRONES
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A new method of synthesizing C-aryl-N-tert-butylnitrones has been devised.These compounds are used universally as trappers of short-lived radicals in the method of spin trap.Nitrones were obtained by oxidation of appropriate para-substituted benzyl-tert-butylamines by means of hydrogen peroxide in presence of sodium tungstate as catalyst.
- Markowicz, Teresa,Skolimowski, Janusz,Skowronski, Romuald
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p. 2505 - 2508
(2007/10/02)
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