- Enantioselective Hydroamination of Alkenes with Sulfonamides Enabled by Proton-Coupled Electron Transfer
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An enantioselective, radical-based method for the intramolecular hydroamination of alkenes with sulfonamides is reported. These reactions are proposed to proceed via N-centered radicals formed by proton-coupled electron transfer (PCET) activation of sulfonamide N-H bonds. Noncovalent interactions between the neutral sulfonamidyl radical and a chiral phosphoric acid generated in the PCET event are hypothesized to serve as the basis for asymmetric induction in a subsequent C-N bond forming step, achieving selectivities of up to 98:2 er. These results offer further support for the ability of noncovalent interactions to enforce stereoselectivity in reactions of transient and highly reactive open-shell intermediates.
- Demaerel, Joachim,Graff, David E.,Knowles, Robert R.,Roos, Casey B.
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supporting information
p. 5974 - 5979
(2020/04/27)
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- Trimethylsilyl-Induced N-O Bond Cleavage in Nitrous Oxide-Derived Aminodiazotates
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The chemical activation of nitrous oxide (N2O) typically results in O-atom transfer and the extrusion of N2 gas. In contrast, reactions of N-trimethylsilyl (TMS)-substituted amides with N2O give inorganic or organic azides
- Liu, Yizhu,Eymann, Léonard Y. M.,Solari, Euro,Fadaei Tirani, Farzaneh,Scopelliti, Rosario,Severin, Kay
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supporting information
p. 11859 - 11863
(2018/09/25)
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- Organo-Cation Catalyzed Asymmetric Homo/Heterodialkylation of Bisoxindoles: Construction of Vicinal All-Carbon Quaternary Stereocenters and Total Synthesis of (-)-Chimonanthidine
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A novel chiral spirocyclic amide (SPA)-derived triazolium organocatalyst has been designed and demonstrated to effect asymmetric homo- and heterodialkylations of various bisoxindoles, enabling enantioselective construction of vicinal all-carbon quaternary stereocenters. These reactions feature excellent enantio- and diastereoselectivities (up to 99% ee and >20:1 dr) as well as good to high yields (up to 89% over two steps). As an application of this methodology, the first asymmetric total synthesis of (-)-chimonanthidine has been achieved.
- Chen, Si-Kai,Ma, Wen-Qiang,Yan, Zhi-Bo,Zhang, Fu-Min,Wang, Shao-Hua,Tu, Yong-Qiang,Zhang, Xiao-Ming,Tian, Jin-Miao
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supporting information
p. 10099 - 10103
(2018/08/23)
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- Phosphino-Triazole Ligands for Palladium-Catalyzed Cross-Coupling
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Twelve 1,5-disubtituted and fourteen 5-substituted 1,2,3-triazole derivatives bearing diaryl or dialkyl phosphines at the 5-position were synthesized and used as ligands for palladium-catalyzed Suzuki-Miyaura cross-coupling reactions. Bulky substrates wer
- Zhao, Yiming,Van Nguyen, Huy,Male, Louise,Craven, Philip,Buckley, Benjamin R.,Fossey, John S.
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supporting information
p. 4224 - 4241
(2018/10/25)
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- Modular Synthesis of Triazole-Based Chiral Iodoarenes for Enantioselective Spirocyclizations
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A new triazole-based C1-symmetrical chiral iodoarene was synthesized in a highly modular route. Based on enzymatic kinetic resolution of an easily accessible propargylic alcohol both enantiomers were accessible in enantiopure form. By Huisgen-type azide-alkyne cycloaddtion a series of differently substituted iodoarenes was synthesized in high overall yields. Finally this novel iodoarene was successfully applied in the oxidative Kita cyclization of naphthol derivatives. Good yields and high ee values were obtained in the asymmetric spirocyclization via in situ generation of the hypervalent iodine species using mCPBA as the terminal oxidant. (Figure presented.).
- Hempel, Christian,Maichle-M?ssmer, Caeciliea,Pericàs, Miquel A.,Nachtsheim, Boris J.
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p. 2931 - 2941
(2017/09/06)
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- Ruthenium Bisammine Complex and Its Reaction with Aryl Azides
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A ruthenium bisammine complex was formed in the reaction of ruthenium 1,4-dibenzyltetraazadiene complex with primary amines at room temperature, which was a versatile precursor for the synthesis of various Ru(II) complexes through ligand exchange reactions. In the reaction with azidobenzene, ruthenium 1,4-diphenyltetraaza-1,3-diene complex was formed, while ruthenium imido complexes were given in the reaction with bulky aryl azides such as 2-azido-1,3-dimethylbenzene and 2-azido-1,3-diisopropylbenzene. The ruthenium imido complexes showed high catalytic activity in the reaction of alkyl azides with primary amines to afford N-substituted imines.
- Park, Jin Yong,Kim, Yongjin,Bae, Dae Young,Rhee, Young Ho,Park, Jaiwook
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supporting information
p. 3471 - 3476
(2017/10/03)
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- 'Click' generated 1,2,3-triazole based organosulfur/selenium ligands and their Pd(II) and Ru(II) complexes: Their synthesis, structure and catalytic applications
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1-(2,6-Diisopropylphenyl)-4-(phenylthio/selenomethyl)-1H-1,2,3-triazole (L1/L2) was synthesized by a 'Click' reaction and treated with [Pd(CH3CN)2Cl2] for 5 h or [(η6-C6H6)RuCl(μ-Cl)]2 for 8 h (followed by reaction with NH4PF6) at room temperature, resulting in complexes [Pd(L)Cl2] (1 and 2) or [(η6-C6H6)Ru(L)Cl]PF6 (3 and 4) (L = L1 or L2), respectively. The four complexes (1-4) and ligands (L1 and L2) were characterized with 1H, 13C{1H} and 77Se{1H} NMR spectroscopy and high resolution mass spectrometry. The single crystal structures of 1-4 were solved. The geometry of Pd in 1 and 2 is distorted square planar. The Pd-S and Pd-Se bond distances in 1 and 2 are 2.277(3) and 2.384(6) ? respectively. In 3 and 4, there is a pseudo-octahedral "piano-stool" type disposition of donor atoms around Ru. The Ru-S and Ru-Se bond lengths in 3 and 4 are 2.3728(12) and 2.4741(6) ? respectively. The catalytic activity of complexes 1 and 2 was explored for Suzuki-Miyaura coupling (SMC) in water and the Sonogashira coupling reaction. For various aryl bromides, including deactivated ones, complexes 1 and 2 were found to be efficient catalysts for both couplings. The optimum loading of 1 and 2 required to catalyze both coupling reactions is of the order of 0.001-2 mol% of Pd. For SMC, no additive or phase transfer catalyst was added. For catalysis of the transfer hydrogenation (TH) of aldehydes and ketones, the half-sandwich Ru(ii) complexes 3 and 4 were explored. Their optimum catalytic loading was found to be 0.1-0.4 mol% of Ru. For TH, both the water solvent and the glycerol hydrogen source are environmentally friendly. The catalytic efficiencies of 3 and 4 are comparable with those reported for other catalysts for TH carried out with 2-propanol or glycerol as a H-source. 1, with a sulfur ligand, is more efficient than 2 (Se analog) for both SMC and the Sonogashira coupling. The activities of 3 and 4 for TH are in the order Se > S.
- Kumar, Satyendra,Saleem, Fariha,Singh, Ajai K.
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p. 11445 - 11458
(2016/07/26)
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- Phosphoramidate tantalum complexes for room-temperature C-H functionalization: Hydroaminoalkylation catalysis
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A cooled reaction: Phosphoramidate-ClTaMe3 complexes promote the first example of room-temperature hydroaminoalkylation catalysis. This reaction can be realized under solvent-free conditions and with challenging substrates such as styrenes and dialkyl amines. When using a vinylsilane substrate, for the first time the linear regioisomer is obtained preferentially using a Group5 metal. TBS=tert-butyldimethylsilyl, TMS=trimethylsilyl. Copyright
- Garcia, Pierre,Lau, Ying Yin,Perry, Mitchell R.,Schafer, Laurel L.
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supporting information
p. 9144 - 9148
(2013/09/12)
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- Redox-active triazolium-derived ligands in nucleophilic fe-catalysis - Reactivity profile and development of a regioselective o-allylation
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Triazolium-derived N-heterocyclic carbene (aNHC) ligands, which are readily accessible by deprotonation of the corresponding triazolium salts, proved to be versatile ligands in diverse allylic substitution reactions. The corresponding triazolium salts are formed from azides and alkynes through the application of 1,3-dipolar cycloaddition and N-alkylation reactions. The unique property of these ligands is to be zwitterionic in their liberated form and to act as strong redox-active σ-donor ligands. By virtue of these qualities, these ligands enable the development of an unprecedented Fe-catalyzed regioselective aryloxylation of allylic carbonates. Copyright
- Klein, Johannes E. M. N.,Holzwarth, Michael S.,Hohloch, Stephan,Sarkar, Biprajit,Plietker, Bernd
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supporting information
p. 6310 - 6316
(2013/10/21)
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- Suzuki-Miyaura cross-coupling reaction catalyzed by PEPPSI-type 1,4-di(2,6-diisopropylphenyl)-1,2,3-triazol-5-ylidene (tzIPr) palladium complex
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A 1,4-di(2,6-diisopropylphenyl)-1,2,3-triazol-5-ylidene (tzIPr)-based PEPPSI-type palladium complex was developed as an excellent precatalyst for the Suzuki-Miyaura cross-coupling reaction. The complex showed high activity under mild conditions for the cross-coupling reactions between various types of aryl chlorides and aryl boronic acids regardless of the steric and electronic nature of the substrates.
- Huang, Jie,Hong, Jong-Tai,Hong, Soon Hyeok
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p. 6630 - 6635
(2013/01/15)
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- Synthesis of calixarene-based bis(iminophosphoranes) and their use in Suzuki-Miyaura cross-coupling
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Calix[4]arene-derived bis(iminophosphoranes) have been synthesised and assessed in palladium-catalysed cross-couplings between phenylboronic acid and aryl bromides orchlorides. TOFs of up to 35100 mol(ArPh formed) mol(Pd) -1 h-1were
- Monnereau, Laure,Semeril, David,Matt, Dominique
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body text
p. 2786 - 2791
(2012/07/01)
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- Cyclopentadienylphosphazene complexes (CpPN Complexes) of metals of the third and fourth group and of the lanthanoids
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The present invention concerns cyclopentadienylphosphazene complexes (CpPN complexes) of the metals of the third and fourth group and of the lanthanoids with the exception of lutetium. The complexes according to the present invention are isolobal and isoe
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Page/Page column 7
(2011/02/26)
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- CRYSTALLINE 1H-1,2,3-TRIAZOL-5-YLIDENES
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The present invention provides novel and stable crystalline 1H-1,2,3 triazolium carbenes and metal complexes of 1H-1,2,3 triazolium carbenes. The present invention also provides methods of making 1H-1,2,3 triazolium carbenes and metal complexes of 1H-1,2,
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Page/Page column 24-25
(2011/11/30)
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- Bis(1,2,3-triazol-5-ylidenes)(i-bitz) as stable 1,4-bidentate ligands based on mesoionic carbenes (MICs)
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Direct metalation of bis(1,2,3-triazolium) salts affords mononuclear rhodium(I) complexes, which feature a 1,4-bidentate bis(1,2,3-triazol-5-ylidene) (i-bitz) ligand. The topology of the ligand is similar to that of 2,20-bipyridines (bpy) and their congen
- Guisado-Barrios, Gregorio,Bouffard, Jean,Donnadieu, Bruno,Bertrand, Guy
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experimental part
p. 6017 - 6021
(2012/01/14)
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- Crystalline 1H-l,2,3-Triazol-5-ylidenes: New stable mesoionic carbenes (MICs)
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Figure Persentation Click makes MICs: A short modular synthesis allows the preparation of novel stable heterocycles that feature a lone pair of electrons on a carbon center. The donor properties of these mesoionic com-pounds are greater than those of classical N-heterocyclic carbenes; they are accessible by deprotonation of the corresponding conjugate acids using comparatively mild bases.
- Guisado-Barrios, Gregorio,Bouffard, Jean,Donnadieu, Bruno,Bertrand, Guy
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supporting information; experimental part
p. 4759 - 4762
(2010/09/15)
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- Simple conversion of aromatic amines into azides
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(Matrix presented) A straightforward and highly efficient synthesis of aromatic azides from the corresponding amines is accomplished using triflyl azide under mild conditions.
- Liu, Qi,Tor, Yitzhak
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p. 2571 - 2572
(2007/10/03)
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- Sterically hindered iminophosphorane complexes of vanadium, iron, cobalt and nickel: a synthetic, structural and catalytic study
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Bis(aryliminophosphoranyl)alkanes L1 = (CH2)n(R12P=NR2)2 (n = 1 or 2, R1 = Ph or Me, R2 = Ph, C6H2Me3-2,4,6 or C6H3Pri2-2,6) reacted with cobalt and nickel dihalides to give chelate complex
- Al-Benna, Sarah,Sarsfield, Mark J.,Thornton-Pett, Mark,Ormsby, Daniel L.,Maddox, Peter J.,Bres, Philippe,Bochmann, Manfred
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p. 4247 - 4257
(2007/10/03)
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