- Cleavage∕cross-coupling strategy for converting β-O-4 linkage lignin model compounds into high valued benzyl amines via dual C–O bond cleavage
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Lignin is the most recalcitrant of the three components of lignocellulosic biomass. The strength and stability of the linkages have long been a great challenge for the degradation and valorization of lignin biomass to obtain bio-fuels and commercial chemicals. Up to now, the selective cleavage of C–O linkages of lignin to afford chemicals contains only C, H and O atoms. Our group has developed a cleavage/cross-coupling strategy for converting 4-O-5 linkage lignin model compounds into high value-added compounds. Herein, we present a palladium-catalyzed cleavage/cross-coupling of the β-O-4 lignin model compounds with amines via dual C–O bond cleavage for the preparation of benzyl amine compounds and phenols.
- Jia, Le,Li, Chao-Jun,Zeng, Huiying
-
-
- Sustainable Production of Benzylamines from Lignin
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Catalytic conversion of lignin into heteroatom functionalized chemicals is of great importance to bring the biorefinery concept into reality. Herein, a new strategy was designed for direct transformation of lignin β-O-4 model compounds into benzylamines and phenols in moderate to excellent yields in the presence of organic amines. The transformation involves dehydrogenation of Cα?OH, hydrogenolysis of the Cβ?O bond and reductive amination in the presence of Pd/C catalyst. Experimental data suggest that the dehydrogenation reaction proceeds over the other two reactions and secondary amines serve as both reducing agents and amine sources in the transformation. Moreover, the concept of “lignin to benzylamines” was demonstrated by a two-step process. This work represents a first example of synthesis of benzylamines from lignin, thus providing a new opportunity for the sustainable synthesis of benzylamines from renewable biomass, and expanding the products pool of biomass conversion to meet future biorefinery demands.
- Guo, Tenglong,Kühn, Fritz E.,Li, Changzhi,Liu, Yuxuan,Wang, Chao,Xiao, Jianliang,Zhang, Bo,Zhang, Tao,Zhao, Zongbao K.
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supporting information
p. 20666 - 20671
(2021/08/25)
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- Copper-Catalyzed Carbonylative Hydroamidation of Styrenes to Branched Amides
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Amides are one of the most ubiquitous functional groups in synthetic and medicinal chemistry. Novel and rapid synthesis of amides remains in high demand. In this communication, a general and efficient procedure for branch-selective hydroamidation of vinylarenes with hydroxyamine derivatives enabled by copper catalysis has been developed for the first time. The reaction proceeds under mild conditions and tolerates a broad range of functional groups. Applying a chiral phosphine ligand, an enantioselective variant of this transformation was achieved, affording a variety of chiral α-amides with excellent enantioselectivities (up to 99 % ee) and high yields.
- Yuan, Yang,Wu, Fu-Peng,Schünemann, Claas,Holz, Jens,Kamer, Paul C. J.,Wu, Xiao-Feng
-
supporting information
p. 22441 - 22445
(2020/10/12)
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- Copper-Catalyzed Asymmetric Hydroamination of Styrenes with pivZPhos as Ligand
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A copper-catalyzed hydroamination of styrenes using pivZPhos as ligand is reported. Enantioselectivities up to 94% are achieved under optimized conditions with aryl and heteroaryl styrenes. A variety of electrophilic O -benzoylhydroxylamines are well tolerated.
- Chen, Chengsheng,Wu, Ling,Wang, Yuwen,Wu, Linglin,Zhang, Yongda
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supporting information
p. 3415 - 3419
(2020/09/15)
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- Formal Synthesis of (–)-Perhydrohistrionicotoxin Using a Thorpe-Ziegler Cyclization Approach. Synthesis of Functionalized Aza-Spirocycles
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The formal synthesis of (–)-PHTX is described. Our approach was based on the anodic cyanation of (S)-1-(1-phenylethyl)-piperidine (–)-1 to afford α-aminonitrile 2 in 85 % yield in a 53:47 dr. The presence of the α-phenylethyl group as the chiral auxiliary
- Vu, Van Ha,Bouvry, Christelle,Roisnel, Thierry,Golhen, Stéphane,Hurvois, Jean-Pierre
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p. 1215 - 1224
(2019/01/04)
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- Iron-Catalysed Reductive Amination of Carbonyl Derivatives with Ω-Amino Fatty Acids to Access Cyclic Amines
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An efficient method for the reductive amination of carbonyl derivatives with ω-amino fatty acids catalysed by an iron complex Fe(CO)4(IMes) [IMes=1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene] by means of hydrosilylation was developed. A variety of pyrrolidines, piperidines and azepanes were selectively synthesised in moderate-to-excellent yields (36 examples, 47–97 % isolated yield) with a good functional group tolerance.
- Wei, Duo,Netkaew, Chakkrit,Carré, Victor,Darcel, Christophe
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p. 3008 - 3012
(2019/05/15)
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- Straightforward α-Amino Nitrile Synthesis Through Mo(CO)6-Catalyzed Reductive Functionalization of Carboxamides
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The selective reduction of amides into an intermediate hemiaminal catalyzed by Mo(CO)6 together with the inexpensive and easy to handle TMDS (1,1,3,3-tetramethyldisiloxane) as reducing agent, followed by subsequent trapping of the hemiaminal with a cyanide source, allows for the straightforward synthesis of α-amino nitriles. The methodology presented here, displays high levels of chemoselectivity allowing for the reduction of amides in the presence of functional groups such as ketones, imines, aldehydes, and acids, which affords a simple route for the synthesis of α-amino nitriles with a broad scope of functionalities in high yields. Furthermore, the applicability of this methodology is demonstrated by scale up experiments and by derivatization of the target compounds into synthetically interesting products. The selective cyanation is successfully applied in late stage functionalizations of amide containing drugs and prolinol derivatives.
- Trillo, Paz,Slagbrand, Tove,Adolfsson, Hans
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p. 12347 - 12351
(2018/09/10)
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- Unusual 1,1-Hydroboration Route to a Reactive Unsaturated Vicinal Frustrated Phosphane/Borane Lewis Pair
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Piers' borane HB(C6F5)2 reacted with the alkyne Mes2P-C≡ ≡C-SiMe3 by a rarely observed 1,1-hydroboration reaction under kinetic control to give the unsaturated vicinal frustrated phosphane/borane Lewis pair 6, featuring both the PMes2 and SiMe3 groups at the same carbon atom C1. Compound 6 is a reactive P/B FLP which splits dihydrogen under mild conditions. Thermolysis at 100 °C converts it to the markedly less reactive P/B FLP regioisomer which bears the -SiMe3 substituent at carbon atom C2 adjacent to the B(C6F5)2 group. Most new compounds were characterized by X-ray diffraction.
- Ueno, Atsushi,Tao, Xin,Daniliuc, Constantin G.,Kehr, Gerald,Erker, Gerhard
-
supporting information
p. 2665 - 2668
(2018/09/10)
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- FLP-Catalyzed Transfer Hydrogenation of Silyl Enol Ethers
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Herein we report the first catalytic transfer hydrogenation of silyl enol ethers. This metal free approach employs tris(pentafluorophenyl)borane and 2,2,6,6-tetramethylpiperidine (TMP) as a commercially available FLP catalyst system and naturally occurring γ-terpinene as a dihydrogen surrogate. A variety of silyl enol ethers undergo efficient hydrogenation, with the reduced products isolated in excellent yields (29 examples, 82 % average yield).
- Khan, Imtiaz,Reed-Berendt, Benjamin G.,Melen, Rebecca L.,Morrill, Louis C.
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supporting information
p. 12356 - 12359
(2018/09/18)
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- Selective formation of heterocyclic: Trans -cycloalkenes by alkyne addition to a biphenylene-based phosphane/borane frustrated Lewis pair
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The intramolecular 1-PMes2/8-B(C6F5)2 substituted biphenylene frustrated Lewis pair 4 shows some behavior reminiscent of intermolecular FLP systems. It undergoes trans-1,2-addition to a series of 1-alkynes to give the respective heterocyclic eight-membered E-alkenes 8. The P/B FLP 4 also reacts with triplet dioxygen to yield the [P]-O-[B](OC6F5) containing oxygenation product.
- Li, Jun,Daniliuc, Constantin G.,Kehr, Gerald,Erker, Gerhard
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supporting information
p. 6344 - 6347
(2018/06/22)
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- Transition-Metal-Free Amine Oxidation: A Chemoselective Strategy for the Late-Stage Formation of Lactams
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A metal-free strategy for the formation of lactams via selective oxidation of cyclic secondary and tertiary amines is described. Molecular iodine facilitates both chemoselective and regioselective oxidation of C-H bonds directly adjacent to a cyclic amine. The mild conditions, functional group tolerance, and substrate scope are demonstrated using a suite of diverse small molecule cyclic amines, including clinically approved drug scaffolds.
- Griffiths, Robert J.,Burley, Glenn A.,Talbot, Eric P. A.
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supporting information
p. 870 - 873
(2017/02/26)
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- SmI2(H2O)n Reduction of Electron Rich Enamines by Proton-Coupled Electron Transfer
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Samarium diiodide in the presence of water and THF (SmI2(H2O)n) has in recent years become a versatile and useful reagent, mainly for reducing carbonyl-type substrates. This work reports the reduction of several enamines by SmI2(H2O)n. Mechanistic experiments implicate a concerted proton-coupled electron transfer (PCET) pathway, based on various pieces of evidence against initial outer-sphere electron transfer, proton transfer, or substrate coordination. A thermochemical analysis indicates that the C-H bond formed in the rate-determining step has a bond dissociation free energy (BDFE) of ~32 kcal mol-1. The O-H BDFE of the samarium aquo ion is estimated to be 26 kcal mol-1, which is among the weakest known X-H bonds of stable reagents. Thus, SmI2(H2O)n should be able to form very weak C-H bonds. The reduction of these highly electron rich substrates by SmI2(H2O)n shows that this reagent is a very strong hydrogen atom donor as well as an outer-sphere reductant.
- Kolmar, Scott S.,Mayer, James M.
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supporting information
p. 10687 - 10692
(2017/08/15)
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- Selective Metal-free HB(C6F5)2Catalyzed Allene Cyclotrimerization: Formation of 1,3,5-Trimethylenecyclohexane and Its Tris-hydroboration Product
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Allene is cyclotrimerized under metal-free conditions with the borane HB(C6F5)2catalyst to selectively give 1,3,5-trimethylenecyclohexane (3 a). Three-fold hydroboration of the 1,3,5-cyclotrimer with Piers’ borane gives the all-cis 1,3,5-CH2B(C6F5)2substituted cyclohexane product 14.
- Tao, Xin,Kehr, Gerald,Daniliuc, Constantin G.,Erker, Gerhard
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supporting information
p. 1376 - 1380
(2017/01/24)
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- Phosphine-Borane Frustrated Lewis Pairs Derived from a 1,1′-Disubstituted Ferrocene Scaffold: Synthesis and Hydrogenation Catalysis
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(Dimesitylphosphino)ferrocene (FcPMes2) (1) reacted with HB(C6F5)2 (2 equiv) by disproportionation to give adduct FcPMes2·H2B(C6F5) (4) plus B(C6F5)3, whereas 1-(dimesitylphosphino)-1′-vinylferrocene (2) was cleanly hydroborated with HB(C6F5)2 to afford [Fe(??5-C5H4PMes2)(??5-C5H4CH2CH2B(C6F5)2)] (7). Compound 7 adopted an open non-interacting P/B frustrated Lewis pair (FLP) structure in the crystal state as well as in a solution. This frustrated Lewis pair heterolytically cleaved dihydrogen under mild conditions to give the respective zwitterionic [P]H+/[B]H- phosphonium/hydroborate product, [Fe(??5-C5H4PHMes2){??5-C5H4CH2CH2BH(C6F5)2}] (8), which served as a catalyst for the hydrogenation of the electron-rich ?€-systems (imine, enamine) as well as the electron-deficient carbon-carbon double and triple bonds in some enones and an ynone under more forcing conditions (50 bar H2 pressure, 50 °C).
- Jian, Zhongbao,Krupski, Sergei,?koch, Karel,Kehr, Gerald,Daniliuc, Constantin G.,Císa?ová, Ivana,?těpni?ka, Petr,Erker, Gerhard
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p. 2940 - 2946
(2017/08/21)
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- A hydroboration route to geminal P/B frustrated Lewis pairs with a bulky secondary phosphane component and their reaction with carbon dioxide
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The secondary aryl-P(H) phosphanyl substituted tert-butylacetylenes 7a,b (aryl: Mes or Mes?) undergo hydroboration with [HB(C6F5)2] to give the geminal vinylidene-bridged P/B Lewis pairs 8a,b. The treatment of 8a,b with benzonitrile, N-sulfinylaniline, and phenyl isothiocyanate, respectively, gives the addition products 12a,b, 13a,b, and 14 with proton transfer from the phosphorus to the more basic nitrogen site. The reaction of the FLPs 8a,b with carbon dioxide yields a doubly boron bonded addition product. The reaction of 8b with a conjugated ynone formally proceeded by trans-1,2-hydrophosphination of the alkyne at the geminal FLP framework to give the seven-membered heterocycle 21.
- Jian, Zhongbao,Kehr, Gerald,Daniliuc, Constantin G.,Wibbeling, Birgit,Erker, Gerhard
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supporting information
p. 11715 - 11721
(2017/09/18)
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- METHOD OF CONVERTING ALCOHOL TO HALIDE
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The present invention relates to a method of converting an alcohol into a corresponding halide. This method comprises reacting the alcohol with an optionally substituted aromatic carboxylic acid halide in presence of an N-substituted formamide to replace a hydroxyl group of the alcohol by a halogen atom. The present invention also relates to a method of converting an alcohol into a corresponding substitution product. The second method comprises: (a) performing the method of the invention of converting an alcohol into the corresponding halide; and (b) reacting the corresponding halide with a nucleophile to convert the halide into the nucleophilic substitution product.
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Page/Page column 56; 150; 153
(2017/01/02)
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- Visible-light-mediated benzylic sp3 C-H bond functionalization to C-Br or C-N bond
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A visible-light-promoted functionalization of unactivated benzylic sp3 C-H bonds was developed. Ethylbenzene derivatives were converted to the corresponding benzyl bromides or afforded benzylamine derivatives in a one-pot manner under visible light photoredox conditions.
- Hou, Tianyuan,Lu, Ping,Li, Pixu
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p. 2273 - 2276
(2016/05/10)
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- Phosphole formation by 1,1-carboboration-reactions of bis-alkynyl phosphanes with a frustrated P/B Lewis pair
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The arylbis(phenylethynyl)phosphanes 1a,b (aryl = mesityl, 2,4,6-triisopropylphenyl) react with the frustrated P/B Lewis pair (P/B FLP) mes2PCH2CH2B(C6F5)2 (4) to give mixtures of three products; the major products, the phosphole systems 2a,b, are formed by a sequence of 1,1-carboboration reactions. One of the minor compounds (6a,b) is formed by 1,1-carboboration followed by internal 1,2-FLP addition to the remaining CC triple bond. The other minor compound of the product mixture (5a,b) is obtained by 1,2-FLP addition to one alkynyl moiety of the starting material. The products 5a, 6b and a derivative of the phosphole 2a (formed by FLP reaction with a terminal alkyne) were characterized by X-ray diffraction. The reaction of the arylbis(pentynyl)phosphanes 1c,d with the FLP 4 selectively gave the respective -B(C6F5)2/-CH2CH2-Pmes2 substituted phospholes 2c,d which were isolated as orange solids in high yields. Rapid strongly temperature dependent equilibration between open and closed P?B FLP isomers was detected for both systems by NMR spectroscopy.
- Klose, Annika,Kehr, Gerald,Daniliuc, Constantin G.,Erker, Gerhard
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supporting information
p. 2023 - 2030
(2016/02/09)
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- Ruthenium(II) and iridium(III) complexes featuring NHC-sulfonate chelate
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Three new complexes bearing a chelating (κ2C,O) NHC-SO3 ligand have been prepared. An original method for the synthesis of the imidazolium-sulfonate NHC precursor is described. The 5-membered ruthena- and irida-cycle containing complexes were fully characterized and evaluated in a series of catalytic transformations involving hydrogen auto-transfer processes.
- Rajaraman,Sahoo,Hild,Fischmeister,Achard,Bruneau
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supporting information
p. 17467 - 17472
(2015/10/19)
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- Functionalization of Intramolecular Frustrated Lewis Pairs by 1,1-Carboboration with Conjugated Enynes
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The vicinal P/B frustrated Lewis pair (FLP) Mes2PCH2CH2B(C6F5)2 undergoes 1,1-carboboration reactions with the Me3Si-substituted enynes to give ring-enlarged functionalized Csub
- Feldmann, Andreas,Kehr, Gerald,Daniliuc, Constantin G.,Mück-Lichtenfeld, Christian,Erker, Gerhard
-
supporting information
p. 12456 - 12464
(2015/08/25)
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- Broad scope hydrofunctionalization of styrene derivatives using iron-catalyzed hydromagnesiation
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The highly regioselective iron-catalyzed formal hydrofunctionalization of styrene derivatives with a diverse range of electrophiles has been developed using a single, operationally simple hydromagnesiation procedure and only commercially available, bench-stable reagents. Using just 0.5 mol % FeCl2·4H2O and N,N,N',N'-tetramethylethylenediamine, hydromagnesiation and electrophilic trapping have been used to form new carbon-carbon bonds (13 examples) and carbon-heteroatom bonds (5 examples) including the products of formal cross-coupling reactions, hydroboration, hydroamination, hydrosilylation, and hydrofluorination.
- Jones, Alison S.,Paliga, James F.,Greenhalgh, Mark D.,Quibell, Jacob M.,Steven, Alan,Thomas, Stephen P.
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p. 5964 - 5967
(2015/01/08)
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- Iron-catalyzed intermolecular hydroamination of styrenes
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An iron-catalyzed formal hydroamination of alkenes has been developed. It features O-benzoyl-N,N-dialkylhydroxylamines as the electrophilic nitrogen source and cyclopentylmagnesium bromide as the reducing agent for intermolecular hydroamination of styrene
- Huehls, C. Bryan,Lin, Aijun,Yang, Jiong
-
supporting information
p. 3620 - 3623
(2014/08/05)
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- Copper-catalyzed intermolecular regioselective hydroamination of styrenes with polymethylhydrosiloxane and hydroxylamines
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Playing Reversi with H and N: A copper-catalyzed intermolecular regioselective hydroamination of styrenes with polymethylhydrosiloxane and hydroxylamine derivatives has been developed. The catalysis accommodates challenging β-substituted substrates. Moreover, the chiral biphosphine-ligated copper complex successfully forms benzylamines with good enantiomeric ratios. Copyright
- Miki, Yuya,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
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supporting information
p. 10830 - 10834
(2013/10/22)
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- Noninteracting, vicinal frustrated P/B-Lewis pair at the norbornane framework: Synthesis, characterization, and reactions
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Hydroboration of dimesitylnorbornenylphosphane with Piers' borane [HB(C6F5)2] gave the frustrated Lewis pair (FLP) 4 in good yield. It has the -PMes2 Lewis base attached at the 2-endo position and the -B(C6F5)2 group 3-exo oriented at the norbornane framework. The vicinal FLP 4 was shown by X-ray diffraction and by spectroscopy to be a rare example of an intramolecular noninteracting pair of a Lewis acid and Lewis base functionality. The FLP 4 rapidly splits dihydrogen heterolytically at ambient temperature to yield the phosphonium/hydrido borate zwitterion 5. It adds to the carbonyl group of benzaldehyde and to carbon dioxide to yield the adducts 6 and 7, respectively. Compounds 5-7 were characterized by X-ray diffraction. Compound 4 adds to the S=O function of sulfur dioxide to give a pair of diastereomeric heterocyclic six-membered ring products due to the newly formed sulfur chirality center, annulated with the norbornane skeleton, which were investigated by 31P/11B single and double resonance solid state NMR experiments. Compound 8 was also characterized by X-ray diffraction. The FLP 4 undergoes a clean N,N-addition to nitric oxide (NO) to give a norbornane annulated five-membered heterocyclic persistent FLP-NO aminoxyl radical 12 (characterized, e.g., by X-ray diffraction and EPR spectroscopy). Additionally, the FLP radical was characterized by 1H solid state NMR spectroscopy. The radical 12 undergoes a H-atom abstraction reaction with 1,4-cyclohexadiene to yield the respective diamagnetic FLP-NOH product 13, which was also characterized by X-ray diffraction and solid state NMR spectroscopy.
- Sajid, Muhammad,Kehr, Gerald,Wiegand, Thomas,Eckert, Hellmut,Schwickert, Christian,Poettgen, Rainer,Cardenas, Allan Jay P.,Warren, Timothy H.,Froehlich, Roland,Daniliuc, Constantin G.,Erker, Gerhard
-
supporting information
p. 8882 - 8895
(2013/07/26)
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- Ru-catalyzed β-selective and enantioselective addition of amines to styrenes initiated by direct arene-exchange
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A catalytic β-selective addition of amines to styrenes proceeded in the presence of cationic Ru complexes combined with diphosphine ligands. In the reaction of α-methylstyrene, an enantioselective addition was achieved by using xylylBINAP.
- Otsuka, Maiko,Yokoyama, Hiroya,Endo, Kohei,Shibata, Takanori
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scheme or table
p. 3815 - 3818
(2012/06/04)
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- Asymmetric hydrogenation of unfunctionalized enamines catalyzed by iridium complexes of chiral spiro N,N-diarylphosphoramidites
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Chiral spiro N,N-diarylphosphoramidites were synthesized. These new chiral spiro monophosphoramidites were efficient ligands for iridium-catalyzed asymmetric hydrogenation of unfunctionalized enamines derived from simple alkyl aryl ketones, providing chiral tertiary amines in good enantioselectivities (up to 90% ee).
- Yan, Pucha,Xie, Jianhua,Zhou, Qilin
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experimental part
p. 1736 - 1742
(2011/07/07)
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- Iridium-catalysed amine alkylation with alcohols in water
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Amines have been directly alkylated with alcohols using 1 mol% [Cp*IrI2]2 catalyst in water in the absence of base or other additives. The Royal Society of Chemistry 2010.
- Saidi, Ourida,Blacker, A. John,Farah, Mohamed M.,Marsden, Stephen P.,Williams, Jonathan M. J.
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supporting information; experimental part
p. 1541 - 1543
(2010/06/12)
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- Borrowing hydrogen in water and ionic liquids: Iridium-catalyzed alkylation of amines with alcohols
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The use of [Cp*IrI2]2 as an efficient catalyst for the alkylation of amines by alcohols in either water or ionic liquid is described. Primary amines are converted into secondary amines, and secondary amines into tertiary amines in the absence of base, and the chemistry has been applied to the synthesis of the analgesic fentanyl. The conversion of primary amines into N-heterocycles by the reaction with diols is also described, along with the N-alkylation of sulfonamides.
- Saidi, Ourida,Blacker, A. John,Lamb, Gareth W.,Marsden, Stephen P.,Taylor, James E.,Williams, Jonathan M. J.
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supporting information; experimental part
p. 1046 - 1049
(2011/03/20)
-
- Ruthenium-catalyzed /V-alkylation of amines and sulfonamides using borrowing hydrogen methodology
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The alkylation of amines by alcohols has been achieved using 0.5 mol percent [Ru(p-cymene)CI2]2 with the bidentate phosphines dppf or DPEphos as the catalyst. Primary amines have been converted into secondary amines, and secondary amines into tertiary amines, including the syntheses of Piribedil, Tripelennamine, and Chlorpheniramine. A/-Heterocyclization reactions of primary amines are reported, as well as alkylation reactions of primary sulfonamides. Secondary alcohols requiremore forcing conditions than primary alcohols but are still effective a lkylating agents in the presence of this catalyst.
- Hamid, M. Haniti S. A.,Allen, C. Liana,Lamb, Gareth W.,Maxwell, Aoife C.,Maytum, Hannah C.,et al.
-
supporting information; experimental part
p. 1766 - 1774
(2009/07/25)
-
- Synthesis of tertiary sec-alkylamines by the addition of grignard reagents to N,N-dialkylformamides mediated by Ti(OiPr)4 and Me3SiCl
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A number of tertiary sec-alkylamines (22 examples, 29-80% yield) have been prepared according to a simple one-pot procedure by the addition of Grignard reagents to N,N-dialkylformamides in the presence of Ti(OiPr)4 and Me3SiCl. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Tomashenko, Olesya,Sokolov, Viktor,Tomashevskiy, Alexander,Buchholz, Herwig A.,Welz-Biermann, Urs,Chaplinski, Vladimir,De Meijere, Armin
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experimental part
p. 5107 - 5111
(2009/06/17)
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- Salt-free synthesis of tertiary amines by ruthenium-catalyzed amination of alcohols
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The amination of secondary alcohols to give tertiary amines in the presence of different in situ generated ruthenium catalysts has been investigated in detail. By applying a combination of [Ru3(CO)12] and N-phenyl-2-(dicyclohexylphosphanyl) pyrrole as the catalyst, cyclic amines can be alkylated with different alcohols in high yield, whereas aliphatic amines gave transalkylation side products. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Tillack, Annegret,Hollmann, Dirk,Mevius, Kathleen,Michalik, Dirk,Baehn, Sebastian,Beller, Matthias
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supporting information; experimental part
p. 4745 - 4750
(2009/05/07)
-
- Metal-free catalytic hydrogenation of enamines, imines, and conjugated phosphinoalkenylboranes
-
(Chemical Equation Presented) The metal-free hydrogen activator 1 catalyzes the unique P/B hydrogenation of the frustrated Lewis pair 3, which itself is inactive toward H2 under the applied conditions, to yield the hydrogenation product 4. System 1/2 (5 mol%) also catalyzes the hydrogenation of a bulky ketimine and of enamines under mild conditions (2.5 bar H2, RT) to yield the respective amines.
- Spies, Patrick,Schwendemann, Sina,Lange, Stefanie,Kehr, Gerald,Froehlich, Roland,Erker, Gerhard
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supporting information; experimental part
p. 7543 - 7546
(2009/03/12)
-
- Anodic cyanation of (S)-(-)-1-1(1-phenylethyl)piperidine: An expeditious synthesis of (S)-(+)-coniine
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A short and efficient asymmetric synthesis of enantiopure (S)-(+)-coniine is reported. Anodic cyanation of (-)-1-[(1S)-1-phenylethyl]piperidine, derived from [(1S)-1-phenylethyl]amine, results in regioselective formation of the corresponding α-amino-nitrile, which was alkylated with propyl iodide to give a bifunctional derivative. The latter underwent a stereoselective reductive decyanation (80% de), the product of which was hydrogenolyzed to afforded (S)-(+)-coniine (99% ee) with an overall 35% yield from (-)-1 -[(1S)-1-phenylethyl]piperidine. Georg Thieme Verlag Stuttgart.
- Girard, Nicolas,Pouchain, Laurent,Hurvois, Jean-Pierre,Moinet, Claude
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p. 1679 - 1682
(2008/02/04)
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- Preparation of non-racemic single-stereocentre α-aminonitriles and a study of their fate in Bruylants reactions
-
A number of chiral carboxamide dehydration methods were investigated for the preparation of four representative enantiomerically enriched α-aminonitriles possessing only one stereogenic centre; best results were observed using Burgess' salt (yield up to 87%, er up to 92/8) or the trifluoroacetic anhydride-triethylamine combination (yield up to 98%, er up to 86/14). Two of the aminonitriles thus obtained were subjected to Bruylants reactions with a methyl Grignard reagent to furnish the corresponding tertiary amines; these products, along with any unreacted starting materials, were obtained essentially in racemic form. In accord with the accepted mechanism for this reaction, a magnesium species is implicated in the formation of an iminium, the common intermediate for both chemical transformation and racemization processes.
- Beaufort-Droal, Virginie,Pereira, Elisabeth,Théry, Vincent,Aitken, David J.
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p. 11948 - 11954
(2007/10/03)
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- Method for producing amines by homogeneously catalyzed reductive amination of carbonyl compounds
-
The invention relates to the preparation of chiral or achiral amines by reaction of aldehydes or ketones with ammonia or primary or secondary amines in the presence of hydrogen and in the presence of homogeneous metal catalysts under mild conditions. Metal catalysts which can be used are complexes of late transition metals with chiral or achiral phosphorus-containing ligands.
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Page/Page column 9; 15-16
(2010/02/11)
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- Direct reductive amination versus hydrogenation of intermediates - A comparison
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The direct reductive amination of acetophenone with benzylamine or piperidine was studied in comparison with the hydrogenation of possible intermediates like a corresponding imine or enamine. No common features in terms of productivity and stereo-control (in the case of chiral catalysts) have been found for both processes. Hence evaluation of efficient, selective and enantioselective catalysts for direct reductive animation appears to be a separate task.
- Tararov, Vitali I.,Kadyrov, Renat,Riermeier, Thomas H.,Fischer, Christine,Boerner, Armin
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p. 561 - 565
(2007/10/03)
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- Transformation of 1,2,5,6-tetrahydropyridines with mycellar fungi
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It has been shown that on biotransformation of a series of 1,2,5,6-tetrahydropyridines with strains of the mycellar fungi Cunninghamella verticillata VKPM F-430, Beauveria bassiana ATCC 7159, and Penicillium simplicissimum KM-16, the culture of Cunninghamella verticillata possesses the greatest transforming activity and selectivity. With the aid of the latter practically quantitative oxidation of 1,2,5,6-tetrahydropyridines occurs into the corresponding trans-diol. The structure and spatial disposition of trans-1-benzyl-3,4-dihydroxypiperidine was demonstrated by data of chromato-mass spectrometric analysis and high resolution NMR spectra and was confirmed by comparison with an authentic sample obtained by an alternate synthesis using the oxidation of 1-benzyl-1,2,5,6-tetrahydropyridine with trifluoroperacetic acid.
- Terentiev,Zilberstein,Borisenko,Shmorgunov,Piskunkova,Grishina
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p. 885 - 890
(2007/10/03)
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- A single step reductive amination of carbonyl compounds with polymethylhydrosiloxane-Ti(O(i)Pr)4
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Highly chemoselective 'one pot' amination of carbonyl groups is achieved using polymethylhydrosiloxane (PMHS) as reductant and Ti(O(i)Pr)4 as activator. A comparative study with other activators such as AlCl3 and Pd-C was also studied.
- Chandrasekhar,Reddy,Ahmed
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p. 1655 - 1657
(2007/10/03)
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- Trichloroacetylhydrazones: New highly reactive alkylating agents
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The behavior of trichloroacylhydrazones as new highly reactive alkylating agents is disclosed; various secondary amines are alkylated within a few minutes at room temperature, and similar alkylating reductions were found with malonates.
- Atlan,Kaim, L. El,Lacroix,Morgentin
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p. 1893 - 1894
(2007/10/03)
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- Asymmetric 1,3-dipolar cycloaddition of optically active trifluoromethylated α,β-unsaturated aryl sulfones with nitrones: The use of 0-dialkylaminoethyl chiral auxiliaries
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Optically active trifluoromethylated α,β-unsaturated aryl sulfones 8a-c, which have a chiral N,N-dialkylaminoethyl group on the ortho position, were synthesized from (S)-1-phenylethylamine 2 and ethyl trifluoroacetate. Asymmetric 1,3-dipolar cycloaddition of sulfones 8a-c with some selected nitrones 9a-c gave the corresponding isoxazolidines 10a-c, 11a-c and 12-15 regio- (> 98%) and diastereo-selectively (36-56% de) in 58-80% yields. The absolute configurations of the cycloadducts were assigned on the basis of X-ray crystallographic analysis of the adduct 10a and by the 1H NMR spectra. The obtained facial selectivity was rationalized by comparison of four possible stable conformers of compound 8a based on AM1 calculations.
- Tsuge, Hiroyasu,Okano, Takashi,Eguchi, Shoji,Kimoto, Hiroshi
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p. 1581 - 1586
(2007/10/03)
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- Formation of heterocycles by the Mitsunobu reaction. Stereoselective ynthesis of (+)-α-skytanthine
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Cyanomethylenetributylphosphorane was shown to mediate the dehydrocyclization of diols and amino alcohols to give the corresponding 6-membered O- and N-heterocycles in 90% or better yields. Using the reaction as a key step, (+)-α-skytanthine, a unique mono terpene alkaloid, was synthesized stereoselectively.
- Tsunoda,Ozaki,Shirakata,Tamaoka,Yamamoto,Ito
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p. 2463 - 2466
(2007/10/03)
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- The effect of the nature of the amine leaving group on the nature of the E2 transition state for the reaction of 1-phenylethylammonium ions with sodium ethoxide in ethanol
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To investigate the effect of the leaving group on the elimination reaction of 1-phenylethylammonium ions with sodium ethoxide in ethanol at 60 deg C, the reaction of seven different quaternary ammonium salts and their β-deuterated analogues with trimethylamine, N-methylpiperidine, N-methyldiethylamine, triethylamine, N,N-dimethylbenzylamine, tripropylamine, and N,N-diethylbenzylamine as leaving groups has been studied.In all cases the elimination, which was shown to proceed via the concerted E2 process, was accompained by competing substitution reactions.Although a significant depedence of the rate of the elimination process on the nature of the leaving group was noted, there was not any linear correlation with the basicity of the amine leaving group.The primary hydrogen-deuterium kinetic isotope effect for the elimination process, (kH/kD)E, was found to increase initially with an increase of reaction rate, kHE, for substrates containing the leaving groups trimethylamine, N-methylpiperidine, N-methyldiethylamine, triethylamine, and N,N-dimethylbenzylamine; i.e., (kH/kD)E=5.03, 5.26, 5.40, 5.83, and 5.85, respectively.A further increase in rate, using substrates with tripropylamine and N,N-diethylbenzylamine as leaving groups resulted in a decrease of the magnitude of the hydrogen-deuterium isotope effect; i.e., (kH/kD)E= 5.42 and 4.67, respectively.It is concluded that steric effects mainly determine leaving group ability.As well, it is concluded that the leaving group ability of the amine determines the structure of the E2 transition state.For the reaction of the poorer leaving groups, trimethylamine, N-methylpiperidine, and N-methyldiethylamine, the proton is more than one-half transferred at the transition state while for reaction involving the two best leaving groups, tripropylamine and N,N-diethylbenzylamine, the Cβ-H bond is less than one-half broken at the transition state.The conclusions are considered in the light of the More O'Ferrall-Jencks potential energy surface diagram.Key words: elimination mechanism, transition state, isotope effects, leaving group, quaternary salts.
- Smith, Peter James,Amin, Md.
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p. 1457 - 1467
(2007/10/02)
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- Alkylative Amination of Non-enolizable Aldehydes with Alkyl(dialkylamino)titanium Derivatives
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The readily available tris(diethylamino)methyltitanium and related compounds (see 1 in Scheme 2) react with non-enolizable aldehydes to give tertiary amines 2; these amines result from direct replacement of the carbonyl O-atom by an alkyl and an amino group (Scheme 3).A tentative mechanism is proposed, according to which the amino group is transferred to the carbonyl C-atom prior to the alkyl group (Scheme 4).
- Seebach, Dieter,Schiess, Martin
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p. 2598 - 2602
(2007/10/02)
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