22385-77-9Relevant academic research and scientific papers
Intermolecular Hydroaminoalkylation of Alkynes
Kaper, Tobias,Fischer, Malte,Thye, Hermann,Geik, Dennis,Schmidtmann, Marc,Beckhaus, Ruediger,Doye, Sven
, p. 6899 - 6903 (2021)
Intermolecular hydroaminoalkylation reactions of alkynes with secondary amines, which selectively give access to allylic amines with E configuration of the alkene unit, are achieved in the presence of titanium catalysts. Successful reactions of symmetrically substituted diaryl- and dialkylalkynes as well as a terminal alkyne take place with N-benzylanilines, N-alkylanilines, and N-alkylbenzylamines.
Biaryl Group 4 Metal Complexes as Non-Metallocene Catalysts for Polyethylene with Long Chain Branching
Gragert, Maria M.,Tomov, Atanas K.,Bettonville, Serge,Pannier, Ga?lle,White, Andrew J. P.,Britovsek, George J. P.
supporting information, p. 4088 - 4092 (2020/11/23)
A series of biaryl Group 4 complexes with a bidentate and a tridentate pincer ligand have been synthesized and characterized. The complexes have been applied as metallocene analogues for the controlled polymerization of ethylene and the copolymerization of ethylene and 1-hexene, with a particular focus on the control of the degree of long chain branching in these polymers.
Linear Hydroaminoalkylation Products from Alkyl-Substituted Alkenes
Warsitz, Michael,Doye, Sven
supporting information, p. 15121 - 15125 (2020/10/23)
The regioselective conversion of alkyl-substituted alkenes into linear hydroaminoalkylation products represents a strongly desirable synthetic transformation. In particular, such conversions of N-methylamine derivatives are of great scientific interest, because they would give direct access to important amines with unbranched alkyl chains. Herein, we present a new one-pot procedure that includes an initial alkene hydroaminoalkylation with an α-silylated amine substrate and a subsequent protodesilylation reaction that delivers linear hydroaminoalkylation products with high selectivity from simple alkyl-substituted alkenes. For that purpose, new titanium catalysts have been developed, which are able to activate the α-C?H bond of more challenging α-silylated amine substrates. In addition, a direct relationship between the ligand structure of the new catalysts and the obtained regioselectivity is described.
Elevated reaction order of 1,3,5-tri-tert-butylbenzene bromination as evidence of a clustered polybromide transition state: a combined kinetic and computational study
Shernyukov, Andrey V.,Genaev, Alexander M.,Salnikov, George E.,Shubin, Vyacheslav G.,Rzepa, Henry S.
supporting information, p. 3781 - 3789 (2019/04/17)
The kinetics and mechanism of concurrent bromo-de-protonation and bromo-de-tert-butylation of 1,3,5-tri-tert-butylbenzene at different bromine concentrations were studied experimentally and theoretically. Both reactions have high order in bromine (experimental kinetic orders ～5 and ～7, respectively). According to quantum chemical DFT calculations, such high reaction orders are caused by participation of clustered polybromide anions Br2n?1- in transition states. Bromo-de-tert-butylation has a higher order due to its bigger reaction center demanding clusters of extended size. A significant primary deuterium kinetic isotope effect (KIE) for bromo-de-protonation is measured indicating proton removal is rate limiting, as confirmed by computed DFT models. The latter predict a larger value for the KIE than measured and possible explanations for this are discussed.
Development of 3,5-Di- tert -butylphenol as a Model Substrate for Biomimetic Aerobic Copper Catalysis
Kwon, Ohhyeon,Esguerra, Kenneth Virgel N.,Glazerman, Michael,Petitjean, Laurène,Xu, Yalun,Ottenwaelder, Xavier,Lumb, Jean-Philip
, p. 1548 - 1553 (2017/08/11)
We develop 3,5-di- tert butylphenol as a strategic substrate for the evaluation of biomimetic Cu 2 -O 2 complexes intended to mimic the activity of tyrosinase. We describe a practical and scalable synthesis and validate its use in an aerobic ortho -oxygenation catalyzed by N, N ′-di- tert -butylethylenediamine and [Cu(CH 3 CN) 4 ]PF 6.
Synthesis of dilactone bridged terphenyls with crankshaft architectures
Dressler, Justin J.,Miller, Sarah A.,Meeuwsen, Brian T.,Riel, Asia Marie S.,Dahl, Bart J.
, p. 283 - 292 (2015/02/02)
Three highly fluorescent dilactone bridged terphenyls with crankshaft architectures have been synthesized. This general class of compounds is relatively unexplored. These compounds have been characterized by fluorescence and UV-vis spectroscopy. For all three compounds, a direct correlation between the rigidity of the terphenyl system and the strength of absorption and emission of light has been observed. Preliminary studies have indicated that compounds with this architecture have the potential to be useful as pH-driven molecular switches and/or sensors with instant fluorescence attenuation at high pH values.
Small molecular neutral microcrystalline iridium(III) complexes as promising molecular oxygen sensors
Li, Ming,Zheng, Baozhan,Luo, Daibing,Sun, Huiqin,Wang, Ning,Huang, Yan,Dai, Jun,Xiao, Dan,Su, Shi-Jian,Lu, Zhiyun
, p. 1926 - 1929 (2015/01/30)
Small molecular neutral Ir(iii) complexes have been demonstrated to be promising self-inclusive microcrystalline thin-film oxygen sensors with relatively high sensitivity (Ksv = 6.41), good stability, and linear Stern-Volmer behavior (R2 = 0.9979).
Stereoselective ring-opening polymerization of a racemic lactide by using achiral salen- and homosalen-aluminum complexes
Nomura, Nobuyoshi,Ishii, Ryohei,Yamamoto, Yoshihiko,Kondo, Tadao
, p. 4433 - 4451 (2008/02/09)
Highly isotactic polylactide or poly(lactic acid) is synthesized in a ring-opening polymerization (ROP) of racemic lactide with achiral salen- and homosalen-aluminum complexes (salenH2 = N,N′-bis(salicylidene) ethylene-1,2-diamine; homosalenH2 = N,N′-bis(salicylidene) trimethylene-1,3-diamine). A systematic exploration of ligands demonstrates the importance of the steric influence of the Schiff base moiety on the degree of isotacticity and the backbone for high activity. The complexes prepared in situ are pure enough to apply to the polymerizations without purification. The crystal structures of the key complexes are elucidated by X-ray diffraction, which confirms that they are chiral. However. analysis of the 1H and 13C NMR spec tra unambiguously demonstrates that their conformations are so flexible that the chiral environment of the complexes cannot be maintained in solution at 25°C and that the complexes are achiral under the polymerization conditions. The flexibility of the back-bone in the propagation steps is also documented. Hence, the isotacticity of the polymer occurs due to a chain-end control mechanism. The highest reactivity in the present system is obtained with the homosalen ligand with 2.2-dimethyl substituents in the backbone (ArCH=NCH2CMe2CH2N=CHAr), whereas tBuMe2Si substituents at the 3-positions of the salicylidene moieties lead to the highest selectivity (Pmeso,= 0.98; T m = 210°C). The ratio of the rate constants in the ROPs of racemic lactide and L-lactide is found to correlate with the stereoselectivity in the present system. The complex can be utilized in bulk polymerization, which is the most attractive in industry, although with some loss of stereoselectivity at high temperature, and the afforded polymer shows a higher melting temperature (Pmeso = 0.92, Tm up to 189°C) than that of homochiral poly(L-lactide) (Tm = 162-180°C). The "livingness" of the bulk polymerization at 130°C is maintained even at a high conversion (97-98%) and for an extended polymerization time (1-2 h).
An examination of VANOL, VAPOL, and VAPOL derivatives as ligands for asymmetric catalytic Diels-Alder reactions
Heller, Douglas P.,Goldberg, Daniel R.,Wu, Hongqiao,Wulff, William D.
, p. 1487 - 1503 (2007/10/03)
Several derivatives of the vaulted biaryl ligand VAPOL were prepared and evaluated as chiral ligands for aluminum Lewis acids in the catalytic asymmetric Diels-Alder reactions of methyl acrylate and methacrolein with cyclopentadiene. The substituents on VAPOL were introduced into the 6- and 6′-positions in an effort to further extend the chiral pocket of the major groove, which contains the phenol functions at the 4- and 4′-positions. The set of four new ligands that have been prepared have the following groups introduced into the 6- and 6′-positions of VAPOL: bromide, methyl, phenyl and 3,5-di-t-butylphenyl. All of these ligands give lower asymmetric inductions than the unsubstituted VAPOL for the Diels-Alder reactions of both methyl acrylate and methacrolein. The positive cooperativity of added carbonyl compounds on the autoinduction in the Diels-Alder reaction of methyl acrylate and cyclopentadiene were also investigated with the VANOL and VAPOL ligands as well as the 6,6′-dibromo and 6,6′-diphenyl derivatives of VAPOL. Only the reaction with VAPOL showed any significant positive cooperativity. The reaction with VANOL was sluggish at -78°C, but at higher temperatures, the reaction did exhibit positive cooperativity that was similar to that of VAPOL. Finally, no positive cooperativity was observed with the VAPOL ligand for the reaction of methacrolein and cyclopentadiene.
Synthesis, crystal structure, and nonlinear optical behavior of β-unsubstituted meso-meso E-vinylene-linked porphyrin dimers
Frampton, Michael J.,Akdas, Huriye,Cowley, Andrew R.,Rogers, Joy E.,Slagle, Jonathan E.,Fleitz, Paul A.,Drobizhev, Mikhail,Rebane, Aleksander,Anderson, Harry L.
, p. 5365 - 5368 (2007/10/03)
(Chemical Equation Presented) A vinylene-linked porphyrin dimer, with no substituents at the β-positions, has been synthesized by CuI/CsF promoted Stille coupling. In the crystal structure of this dimer, the C2H 2 bridge is twisted by 45° relative to the plane of the porphyrins. The absorption, emission spectra, and electrochemistry reveal substantial porphyrin-porphyrin π-conjugation. The triplet excited-state absorption spectrum of this dimer makes it suitable for reverse saturable absorption at 710-900 nm.
