59904-10-8Relevant academic research and scientific papers
Alkyne hydroamination and trimerization with titanium bis(phenolate) pyridine complexes: Evidence for low-valent titanium intermediates and synthesis of an ethylene adduct of titanium(II)
Tonks, Ian A.,Meier, Josef C.,Bercaw, John E.
, p. 3451 - 3457 (2013/07/26)
A class of titanium precatalysts of the type (ONO)TiX2 (ONO = pyridine-2,6-bis(4,6-di-tert-butylphenolate); X = Bn, NMe2) has been synthesized and crystallographically characterized. The (ONO)TiX2 (X = Bn, NMe2, X2 = NPh) complexes are highly active precatalysts for the hydroamination of internal alkynes with primary arylamines and some alkylamines. A class of titanium imido/ligand adducts, (ONO)Ti(L)(NR) (L = HNMe2, py; R = Ph, tBu), have also been synthesized and characterized and provide structural analogues to intermediates on the purported catalytic cycle. Furthermore, these complexes exhibit unusual redox behavior. (ONO)TiBn2 (1) promotes the cyclotrimerization of electron-rich alkynes, likely via a catalytically active TiII species that is generated in situ from 1. Depending on reaction conditions, these TiII species are proposed to be generated through Ti benzylidene or imido intermediates. A formally TiII complex, (ONO)Ti II(η2-C2H4)(HNMe2) (7), has been prepared and structurally characterized.
Ti(NMe2)4-catalyzed Markovnikov hydroamination of alkynes in the presence of N-heterocyclic carbenes and LiN(SiMe3)2
Takaki, Ken,Koizumi, Sadayuki,Yamamoto, Yuta,Komeyama, Kimihiro
, p. 7335 - 7337 (2007/10/03)
Intermolecular hydroamination of alkynes catalyzed by Ti(NMe2)4 was much improved with N-heterocyclic carbenes and LiN(SiMe3)2, by which high Markovnikov selectivity was attained for the coupling of nearly all a
New C-N and C-C bond forming reactions catalyzed by titanium complexes
Odom, Aaron L.
, p. 225 - 233 (2007/10/03)
Titanium(iv) complexes with two basic dimethylamido ligands can be efficient catalysts for alkyne hydroamination by primary amines. Readily prepared pyrrolyl ligands have proven to be especially useful in generating active catalysts for hydroamination and
Titanium dipyrrolylmethane derivatives: Rapid intermolecular alkyne hydroamination
Shi, Yanhui,Hall, Christopher,Ciszewski, James T.,Cao, Changsheng,Odom, Aaron L.
, p. 586 - 587 (2007/10/03)
Alkynes are rapidly hydroaminated by primary amines using titanium dipyrrolylmethane derivatives as catalyst.
Synthesis and structure of 2-aryl-2,4-dimethyl-1,2,3,4-tetrahydroquinolines and 1,3-disubstituted indenes
Zvolinskii,Kryvenko,Sergeeva,Soldatenkov,Prostakov
, p. 86 - 90 (2007/10/03)
It has been shown that the intramolecular cyclization of N-(1-arylbutenyl)arylamines under acid catalysis conditions may proceed in two directions with the formation of 2-aryl-2,4-dimethyl-1,2,3,4-tetrahydroquinolines and 1,3 disubstituted indenes. 1997 P
Enantioselective hydrogenation of imines with chiral (phosphanodihydrooxazole)iridium catalysts
Schnider, Patrick,Koch, Guido,Pretot, Roger,Wang, Guozhi,Bohnen, Frank Michael,Krueger, Carl,Pfaltz, Andreas
, p. 887 - 892 (2007/10/03)
Cationic iridium(I) complexes of chiral phosphanodihydrooxazoles were used as catalysts for the enantioselective hydrogenation of prochiral N-alkyl and N-aryl imines. The complexes are air-stable crystalline solids that can be readily prepared and are easy to handle. The structures of two complexes were determined by X-ray analysis. For N-alkyl imines of acetophenone, enantiomeric excesses of up to 79% were obtained. Dialkyl ketimines and cyclic imines showed lower reactivity and selectivity. A remarkable dilution effect was observed for the hydrogenation of the N-phenyl imine of acetophenone: decreasing the substrate and catalyst concentration led to a significant improvement of the enantioselectivity. Thus, up to 89% ee could be achieved using 0.1 mol% of catalyst. The highest enantioselectivities were obtained in weakly coordinating solvents such as CH2C12. Additives such as halides, imides, or amines were found to poison the catalyst. Hydrogen pressures of 100 bar were usually employed, but in some cases identical results were achieved with only 1 bar H2.
Azomethines, 1-Azaallyl Anions, and Metastable Secondary Enamines
Knorr, Rudolf,Weiss, Alfons,Loew, Peter,Raepple, Edith
, p. 2462 - 2489 (2007/10/02)
E/Z equilibrium constants of the ketone anils 6a-s do not depend significantly on the inductive substituent effect. 1H NMR chemical shifts used for configurational classification are also effective for assignments in comparable, isomerically almost pure azomethines 6aa-pp and may be explained by the anisotropic shift model.The 1-azaallyl anions 7 prepared by deprotonation are characterized by 1H NMR spectroscopy.Kinetic and thermodynamic control of this metallation reaction result in different preferential configurations of such anions, the methanolysis of which yields metastable sec. enamines 8 by regio- and stereospecific N-protonation.It is possible to estimate further substituent parameters λd from E/Z equilibria.
