15429-16-0Relevant academic research and scientific papers
Metal-Free Carbonylation Route to a Reactive Borataepoxide System
Wang, Tongdao,Kehr, Gerald,Daniliuc, Constantin G.,Erker, Gerhard
, p. 1040 - 1049 (2018)
Hydroboration of N-allyl-cis-2,6-dimethylpiperidine with HB(C6F5)2 gave the trimethylene-bridged frustrated N/B Lewis pair 7. It featured a trans-2,6-dimethyl substitution pattern at the piperidine unit which indicated preceding equilibration with its iminium cation/hydridoborate isomer 6 by means of an internal hydride transfer. In situ generated compound 6 is essential for the reaction with CO/HB(C6F5)2 to give the borataepoxide product 12 at the [N]-(CH2)3-[B] framework. The borataepoxide 12 reacts rapidly with CO2, cleaves the acidic C-H bond of a terminal alkyne, splits dihydrogen, and reacts with nitriles and benzaldehyde. Most products were characterized by X-ray diffraction.
Frustrated Lewis Pair Chemistry Derived from Bulky Allenyl and Propargyl Phosphanes
Rosorius, Christoph,M?ricke, Jennifer,Wibbeling, Birgit,McQuilken, Alison C.,Warren, Timothy H.,Daniliuc, Constantin G.,Kehr, Gerald,Erker, Gerhard
, p. 1103 - 1113 (2016)
The dimesitylpropargylphosphanes mes2P-CH2-C≡C-R 6 a (R=H), 6 b (R=CH3), 6 c (R=SiMe3) and the allene mes2P-C(CH3)=C=CH2 (8) were reacted with Piers' borane, HB(C6F5)2. Compound 6 a gave mes2PCH2CH=CH(B(C6F5)2] (9 a). In contrast, addition of HB(C6F5)2 to 6 b and 6 c gave mixtures of 9 b (R=CH3) and 9 c (R=SiMe3) with the regioisomers mes2P-CH2-C[B(C6F5)2]=CRH 2 b (R=CH3) and 2 c (R=SiMe3), respectively. Compounds 2 b,c underwent rapid phosphane/borane (P/B) frustrated Lewis pair (FLP) reactions under mild conditions. Compound 2 c reacted with nitric oxide (NO) to give the persistent FLP NO radical 11. The systems 2 b,c cleaved dihydrogen at room temperature to give the respective phosphonium/hydridoborate products 13 b,c. Compound 13 c transferred the H+/H- pair to a small series of enamines. Compound 13 c was also a metal-free catalyst (5mol %) for the hydrogenation of the enamines. The allene 8 reacted with B(C6F5)3 to give the zwitterionic phosphonium/borate 17. The -PPh2-substituted mes2P-propargyl system 6 d underwent a typical 1,2-P/B-addition reaction to the C≡C triple bond to form the phosphetium/borate zwitterion 20. Several products were characterized by X-ray diffraction.
New approach for induction of alkyl moiety to aliphatic amines by NaBH(OAc)3 with carboxylic acid
Tamura, Satoru,Sugawara, Aoi,Sato, Erika,Sato, Fuka,Sato, Keigo,Kawano, Tomikazu
supporting information, (2020/04/15)
We had found the novel N-alkylation method, which utilizes carboxylic acids as alkyl sources with sodium triacetoxyborohydride [NaBH(OAc)3]. Our methodology had been revealed to have some advantages over the reported similar procedures. Through
Phosphole formation by 1,1-carboboration-reactions of bis-alkynyl phosphanes with a frustrated P/B Lewis pair
Klose, Annika,Kehr, Gerald,Daniliuc, Constantin G.,Erker, Gerhard
supporting information, p. 2023 - 2030 (2016/02/09)
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.
Remarkable co-catalyst effects on the enantioselective hydrogenation of unfunctionalised enamines: Both enantiomers of product from the same enantiomer of catalyst
Tin, Sergey,Fanjul, Tamara,Clarke, Matthew L.
, p. 677 - 680 (2016/02/18)
During studies on the enantioselective hydrogenation of unfunctionalised enamines, a very surprising switch in enantiopreference was observed; [((R,R)-Et-DUPHOS)-Rh(COD)]BF4 hydrogenates an enamine to give (R)-amine with up to 73% ee, but when
Internal adduct formation of active intramolecular C4-bridged frustrated phosphane/borane Lewis pairs
Wang, Xiaowu,Kehr, Gerald,Daniliuc, Constantin G.,Erker, Gerhard
supporting information, p. 3293 - 3303 (2014/03/21)
The tetramethylene-bridged PMes2/B(C6F 5)2 frustrated Lewis pair (FLP) 8 was prepared by hydroboration of Mes2P-(CH2)2CH=CH2 with HB(C6F5)2. It is an active FLP that splits dihydrogen under mild conditions and, consequently, serves as a metal-free hydrogenation catalyst for a variety of substrates. It also reacts typically with terminal acetylenes. The C4-bridged FLP 23 was prepared by HB(C6F5)2 hydroboration of 1- dimesitylphosphino-2-vinylferrocene. It represents a rare example of a FLP where the equilibrium between the open form and the closed internal P/B adduct form is experimentally observable. It also shows a variety of typical FLP reactions, including dihydrogen splitting. The FLPs 8 and 23 (open form) and many precursors and products were characterized by X-ray diffraction.
Iron-catalyzed intermolecular hydroamination of styrenes
Huehls, C. Bryan,Lin, Aijun,Yang, Jiong
supporting information, p. 3620 - 3623 (2014/08/05)
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
Copper-catalyzed intermolecular regioselective hydroamination of styrenes with polymethylhydrosiloxane and hydroxylamines
Miki, Yuya,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
supporting information, p. 10830 - 10834 (2013/10/22)
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
Structural models of vanadate-dependent haloperoxidases, their reactivity, immobilization on polymer support and catalytic activities
Maurya, Mannar R.
scheme or table, p. 215 - 228 (2012/03/12)
The design of structural and functional models of enzymes vanadate-dependent haloperoxidases (VHPO) and the isolation and/or generation of species having {VO(H2O)}, {VO2}, {VO(OH)} and {VO(O 2)} cores, proposed as intermediate(s) during catalytic action, in solution have been studied. Catalytic potential of these complexes have been tested for oxo-transfer as well as oxidative bromination and sulfide oxidation reactions. Some of the oxidovanadium(IV) and dioxidovanadium(V) complexes have been immobilized on polymer support in order to improve their recycle ability during catalytic activities and turn over number. The formulations of the polymer-anchored complexes are based on the respective neat complexes and conclusions drawn from the various characterization studies. These catalysts have successfully been used for all catalytic reactions mentioned above. These catalysts are stable and recyclable. Indian Academy of Sciences.
Ruthenium-catalyzed ionic hydrogenation of iminium cations. Scope and mechanism
Guan, Hairong,Iimura, Masanori,Magee, Matthew P.,Norton, Jack R.,Zhu, Guang
, p. 7805 - 7814 (2007/10/03)
Catalysis by CpRu(P-P)H (where P-P Is a chelating diphosphine) of the ionic hydrogenation of an iminium cation inolves (1) the transfer of H- to form an amine, (2) the coordination of H2 to the resulting Ru cation, and (3) the transfer of H+ from the coordinated dihydrogen to the amine formed in (1). With CpRu(dppe)H the principal Ru species during catalysis remains the hydride complex, and H2 pressure has no effect on either the ee or the turnover frequency. Step (1), H- transfer, can be carried out stoichiometrically if the H2 is replaced by a coordinating solvent. A methyl substituent on the Cp ring decreases the H - transfer rate and the turnover frequency slightly. Electron-donating substituents on the phosphine increase the H- transfer rate and increase the turnover frequency up to a point: eventually the hydride ligand (i.e., the one in Cp*Ru(dmpe)H) becomes sufficiently basic to deprotonate the iminium cation to the corresponding enamine, and this pre-equilibrium competes with H- transfer. Ionic hydrogenation of enamines is possible when a Ru(H2) cation (i.e., [CpRu(dppm) (η2-H2)]+) is used as the catalyst and the enamine is more basic than the product amine. Ionic hydrogenation of an α/β-unsaturated iminium cation saturates both the C=C and the C=N bonds. A C=N bond is more reactive toward ionic hydrogenation than a C=C one, but in some cases (i.e., CH=CH2) the latter may compete with H 2 for a coordination site and decrease the turnover frequency.
