82299-16-9Relevant academic research and scientific papers
A Highly Selective Manganese-Catalyzed Synthesis of Imines under Phosphine-Free Conditions
Chai, Huining,Yu, Kun,Liu, Bo,Tan, Weiqiang,Zhang, Guangyao
, p. 217 - 226 (2020/01/31)
An efficient and highly selective phosphine-free NN-manganese(I) complex catalyst system was developed for the acceptorless dehydrogenative coupling of alcohols with amines to form imines. The coupling reactions underwent at 3 mol % catalyst loading, and a large range of alcohols and amines with diverse functional groups was applied, including challenging diol and diamine. The target imine products were obtained in good to excellent yields. The present work provides an alternative method to construct highly active nonprecious metal complex catalysts based on phosphine-free ligands.
Slow anion exchange, conformational equilibria, and fluorescent sensing in venus flytrap aminopyridinium-based anion hosts
Wallace, Karl J.,Belcher, Warwick J.,Turner, David R.,Syed, Kauser F.,Steed, Jonathan W.
, p. 9699 - 9715 (2007/10/03)
The synthesis, anion binding, and conformational properties of a series of 3-aminopyridinium-based, tripodal, tricationic hosts for anions are described. Slow anion and conformational exchange on the 1H NMR time scale at low temperature, coupled with NMR titration, results in a high level of understanding of the anion-binding properties of the compounds, particularly with respect to significant conformational change resulting from induced fit complexation. Peak selectivity for halides, particularly Cl-, is observed. The approach has been extended to dipodal and tripodal podands based on 3-aminopyridinium "arms" containing photoactive anthracenyl moieties. The 1,3,5-tripodal host shows a remarkable selectivity for acetate over other anions, in contrast to the analogous unsubstituted tris(3-aminopyridinium) analogue, despite the fact that low-temperature 1H NMR experiments reveal a total of four acetate-binding conformations. Photodimerization of anthracene units results in the formation of potential fluorescent anion sensors.
Molecular structure of di-aryl-aldimines by multinuclear magnetic resonance and X-ray diffraction
Montalvo-González, Rubén,Ariza-Castolo, Armando
, p. 375 - 389 (2007/10/03)
The complete 1H, 13C and 15N NMR analyses for a series of 25 diaryl-aldimines containing phenyl, pyridyl, pyrazolone and furanyl moieties are described herein. Detailed evaluation of substituent chemical shift and coupling constant effects showed that interaction between the lone pair of the pyrazolone carbonyl group or the nitrogen of 2-substitued pyridines with the aldimine hydrogen increases the 1JCH value and shifts the resonance signal for this hydrogen to high frequency, in the 1H NMR spectra. The X-ray crystal structure analysis of pyrazolone substituted aldimines evidenced the planarity of the aryl groups which are conjugated with the C=N double bond. In the case of the N-(2-pyridinemethylene)-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-one, two rotamers were observed in the same unit cell.
Oxidative rearrangement of imines to formamides using sodium perborate
Nongkunsarn, Pakawan,Ramsden, Christopher A.
, p. 3805 - 3830 (2007/10/03)
Oxidation of C-aryl or alkyl-N-arylaldimines 6 or 20 by sodium perborate tetrahydrate (SPB) in trifluoroacetic acid solution gives rearranged N,N-disubstituted formamides 9 and 21. Yields are variable and solvent dependant with the best yields (50-60%) being obtained for electronically neutral C-aryl substituents or C-s-alkyl substituents. Product formation is rationalised in terms of an intermediate oxaziridine 5 that rearranges via acid catalysed O-N bond cleavage. An alternative C-O bond cleavage of these intermediates accounts for the formation of aldehydes, which are common by products. Rearrangement appears to be favoured by N-aryl substituents and by C-substituents that do not stabilise a developing positive charge on carbon. Further support for an oxaziridine intermediate 5 is provided by the observation that MCPBA oxidation of benzaldehyde phenylimine gives rearranged N,N-diphenylformamide. Under the conditions of the SPB oxidative rearrangements, oxaziridine formation may well occur by initial formation of trifluoroperacetic acid. Stereochemical aspects of this novel rearrangement of aldimines 1 → 2 have been investigated using trans- and cis-myrtanal 25 and 30. The observed epimerisation using die N-4-tolyl imine of trans-myrtanal 26 is believed to arise from equilibration of the precursor imine 26 with the tautomeric enamine 35b.
NEW SYNTHETIC METHODOLOGY FOR THE PREPARATION OF SUBSTITUTED 1-ARYL-1-PYRIDYLAMINOMETHANEPHOSPHONIC ACID ESTERS
Burkhouse, David W.,Zimmer, Hans
, p. 1437 - 1448 (2007/10/02)
Esters of 1-phenyl-1-pyridylaminomethanephosphonates generally cannot, or only in poor yields be prepared by the usual methods by treatment of the appropriate Schiff base with diethyl or diphenyl phosphite.However, it was found that these phosphonates are
193. Photoformation of (Z)-Isomers in Diarylazomethines. Part IV. Direct and Sensitized Photoisomerization of Pyridyl Analogues of Benzylidene-aniline and Absorption Spectra of their (Z)-Isomers
Maeda, Koko,Fischer, Ernst
, p. 1961 - 1965 (2007/10/02)
UV irradiation of solutions of the (E)-isomers of five (out of the possible six) monopyridyl analogues at reduced temperatures results in extensive (80-90percent) conversion into the corresponding (Z)-isomers.The process is reversible both thermally and photochemically.The (Z)-isomers are stable at temperatures below -80 deg, and their absorption spectra were estimated.Biacetyl-photosensitized (E)->(Z) isomerization was observed, with (Z)-contents of ca. 70percent at the photostationary state.
