57229-08-0Relevant academic research and scientific papers
Zinc Powder Catalysed Formylation and Urealation of Amines Using CO2 as a C1 Building Block?
Du, Chongyang,Chen, Yaofeng
, p. 1057 - 1064 (2020/06/30)
Transformation of CO2 into valuable organic compounds catalysed by cheap and biocompatible metal catalysts is one of important topics of current organic synthesis and catalysis. Herein, we report the zinc powder catalysed formylation and urealation of amines with CO2 and (EtO)3SiH under solvent free condition. Using 2 molpercent zinc powder as the catalyst, a series of secondary amines, both the aromatic ones and the aliphatic ones, can be formylated into formamides. When primary aromatic amines were used as the substrates, the reactions produce urea derivatives. The electronic and steric effects from the substrates on the formylation and urealation reactions were observed and discussed. The recovery and reusability of zinc powder were investigated, showing the zinc powder can be reused in the formylation reaction without loss of catalytic activity. The analysis on the reactants/products mixture after filtering out the zinc powder showed the zinc concentration in the mixture is low to 1 ppm. The pathways for the formylation and urealation of amines with this catalytic system were also investigated, and related to the different substrates.
Organic ligand-free carbonylation reactions with unsupported bulk Pd as catalyst
Liu, Shujuan,Wang, Hongli,Dai, Xingchao,Shi, Feng
supporting information, p. 3457 - 3462 (2018/08/06)
Herein, surprising results for bulk Pd-catalyzed carbonylation reactions are presented. Three types of carbonylation reactions can be realized efficiently under organic ligand-free conditions, namely, hydroaminocarbonylation of olefins, aminocarbonylation of aryl iodides and oxidative carbonylation of amines, which almost cover all the known mechanisms in carbonylation reactions. Notably, the bulk Pd catalyst system exhibited better catalytic activity than the classical homogeneous PdCl2/(2-OMePh)3P catalyst system. This study will create a momentous and new field of green carbonylation reactions.
Hydrogen-Bonded Homoleptic Fluoride-Diarylurea Complexes: Structure, Reactivity, and Coordinating Power
Pfeifer, Lukas,Engle, Keary M.,Pidgeon, George W.,Sparkes, Hazel A.,Thompson, Amber L.,Brown, John M.,Gouverneur, Véronique
supporting information, p. 13314 - 13325 (2016/10/22)
Hydrogen bonding with fluoride is a key interaction encountered when analyzing the mode of action of 5′-fluoro-5′-deoxyadenosine synthase, the only known enzyme capable of catalyzing the formation of a C-F bond from F-. Further understanding of the effect of hydrogen bonding on the structure and reactivity of complexed fluoride is therefore important for catalysis and numerous other applications, such as anion supramolecular chemistry. Herein we disclose a detailed study examining the structure of 18 novel urea-fluoride complexes in the solid state, by X-ray and neutron diffraction, and in solution phase and explore the reactivity of these complexes as a fluoride source in SN2 chemistry. Experimental data show that the structure, coordination strength, and reactivity of the urea-fluoride complexes are tunable by modifying substituents on the urea receptor. Hammett analysis of aryl groups on the urea indicates that fluoride binding is dependent on σp and σm parameters with stronger binding being observed for electron-deficient urea ligands. For the first time, defined urea-fluoride complexes are used as fluoride-binding reagents for the nucleophilic substitution of a model alkyl bromide. The reaction is slower in comparison with known alcohol-fluoride complexes, but SN2 is largely favored over E2, at a ratio surpassing all hydrogen-bonded complexes documented in the literature for the model alkyl bromide employed. Increased second-order rate constants at higher dilution support the hypothesis that the reactive species is a 1:1 urea-fluoride complex of type [UF]- (U = urea) resulting from partial dissociation of the parent compound [U2F]-. The dissociation processes can be quantified through a combination of UV and NMR assays, including DOSY and HOESY analyses that illuminate the complexation state and H-bonding in solution.
Copper catalyzed arylation of urea
Nandakumar, Mecheril V.
, p. 1989 - 1990 (2007/10/03)
An efficient copper catalyzed amidation of aryl iodides with urea is described. This method is milder than the palladium catalyzed arylation and avoids the use of toxic phosphine ligands.
N,N′-disubstituted ureas: Influence of substituents on the formation of supramolecular polymers
Lortie, Frederic,Boileau, Sylvie,Bouteiller, Laurent
, p. 3008 - 3014 (2007/10/03)
Symmetrical N,N′-disubstituted ureas have been synthesized and characterized. Among them, the branched dialkylureas prepared are highly soluble in organic media. Moreover, the solutions obtained are very viscous in heptane, if the branched alkyl groups are not too bulky (i.e. a methyl group on the α carbon, or an ethyl group on the β carbon). Due to the strong, bifurcated hydrogen bonds between the urea moieties, linear supramolecular polymers are formed. The degree of association of these supramolecular polymers has been determined by FTIR spectroscopy.
