Ring-chain isomerism of 1,3,3-trimethyl-2-formylmethylene-indoline (fischer aldehyde) oxime and associated reactions (original) (raw)
Journal of Chemical Crystallography, 2010
Abstract Schiff base 4-[(2-hydroxy-3-methoxybenzylideneamino)-N-(5-methylisoxazol-3-yl)benzene-sulfonamide has been synthesized from the reaction of 4-amino-N-(5-methylisoxazol-3-yl)benzenesulfonamide(sulfamethoxazole) with 2-hydroxy-3-methoxybenzaldehyde. It has been characterized by elemental analysis, MS, IR, 1H NMR, 13C NMR, HETCOR and UV–Visible techniques. The structure of it also has been examined crystallographically. For the compound exist as dominant form of enol-imines in both the solid state and the solutions. It crystallizes in the monoclinic space group P21/c with a = 8.2694(7), b = 8.3453(5), c = 26.260(2) Å, β = 97.142(7) °, V = 1798.1(2) Å3, D x = 1.431 g cm−3, R 1 = 0.0529 and wR 2 = 0.1370 [I > 2σ(I)], respectively. Index Abstract The tautomerism in the Schiff base ligands plays an important role for distinguishing their photochromic and thermochromic characteristics. Both phenomena is associated with a proton transfer (enol-imine, O–H···N, keto-amine, O···H–N).
HETEROCYCLES, 1994
Whereas 1,3,10,10a-tetrahydro-5H-oxazolo[3,4-b]isoquinoline adopts an equilibrium in CDC13 solution at 295 K in which the trans-fused conformation predominates, 1,5,6,l0b-tetrahydro-3H-oxazolo[4,3-alisoquinoline adopts the 0-inside cis-fused conformation. This difference in conformational preference has been explained partly in terms of ring-fusion strain. Perhydro-oxazolo[3,4-alppidine adopts a conformational equilibriumZ in CDC13 solution at 298 K between 67% trans-fused conformer (1-t) and 33% 0-inside cis-fused conformer (1-c) whereas indolizidine shows3 an extreme preference for the trans-conformer (2-1). In addition to differences in non-bonded interactions between the two systems4 and the generalised anomeric effectS in 1, ring fusion strain (cf. trans-hydrindane6) may also be partially responsible for the difference in positions of conformational equilibria. Any ring fusion strain present in trans-indolizidine (24) is expected4,7 to increase in trans-perhydro-oxazolo[3,4-alpyridine (I-t) as a result of the sho~ter C-0 bonds (1.43A) in 1-t compared to the corresponding CC bonds (1.54A) in 24. The magnitude of such strain should be affected by changes in the conformation of the six-membered ring and accordingly 1,3,10,10a-tetrahydro-5H-oxazolo[3,4-b]isoquinoline (3) and 1,5,6.10b-tetrahydr0-3Hoxazolo[4.3-a]iso~uinoline (4) containing non-chair piperidine rings were chosen for study.
DFT, FT-IR, FT-Raman and NMR studies of 4-(substituted phenylazo)-3,5-diacetamido-1H-pyrazoles
Journal of Molecular Structure, 2011
We present a detailed analysis of the structural and vibrational spectra of some novel azo dyes. 2-(Substituted phenylazo)malononitriles were synthesized by the coupling reaction of the diazonium salts, which were prepared with the use of various aniline derivatives with malononitrile, and then 4-(substituted phenylazo)-3,5-diamino-1H-pyrazole azo dyes were obtained via the ring closure of the azo compounds with hydrazine monohydrate. The experimental and theoretical vibrational spectra of azo dyes were studied. The structural and spectroscopic analysis of the molecules were carried out by using Becke's three-parameters hybrid functional (B3LYP) and density functional harmonic calculations. The 1 H nuclear magnetic resonance (NMR) chemical shifts of the azo dye molecules were calculated using the gaugeinvariant-atomic orbital (GIAO) method. The calculated vibrational wavenumbers and chemical shifts were compared with the experimental data of the molecules.
1. INTRODUCTION The synthesis of halogen substituted isoxazoline derivatives has increase the attention as a source of new pharmacological agents. The isoxazoline derivatives have been reported to possess antifungal 1 , antimicrobial 2 , antitumor 3 , anti-inflammatory 4,5 , antidepressant 6,7 and analgesic 8 activity. The halogen group can alter the course of the reaction as well as the biological activities. In addition, isoxazoline derivatives have played a crucial role in the theoretical development of heterocyclic chemistry and are also used extensively in organic synthesis 9,10. For study of halogen substituted isoxazoline drug, mainly study the effect of halogen group over the drug activity is important. To study such effect the synthesis of isoxazoline is not necessary. Many theoretical methods are available like QSAR, ab-initio, semi-imperical, DFT, HF method etc, to predict such drug activity without synthesis. Amongst these, the DFT method has commonly used to determined molecular effect of halogen group on pharmacological activity 11. In this work we have studied the computational method for 8-(5-((4-fluoro phenyl)amino)-4-(4chlorobenzoyl)-4,5-dihydroisoxazole-3-yl)-7-hydroxy-4-methyl-2H-chromen-2-one (Ia) and 8-(5-((4chlorophenyl)amino)-4-(4-chlorobenzoyl)-4,5-dihydroisoxazole-3-yl)-7-hydroxy-4-methyl-2H-chromen-2-one (Ib) including electronic structure spectroscopic and thermo-dynamical properties. 2. COMPUTATIONAL DETAILS The ground state geometry optimizations were carried out at the DFT 12-16 using the modified hybrid functional of Perdew, Burke and Ernzerhof (PBE1PBE) 17,18 with the 6-311g basis set 19-23. Electronic absorption spectra were computed as vertical electronic excitations from the ground state using TD-DFT 24-26 with PBE1PBE/6-311g basis set. The optimized structural parameters were used for vibrational frequency calculation to characterize all the stationary points as minima. All the calculations performed with Gaussian-03 package 27. Molecular visualization and the vibrational frequency assignment were made by using Gauss View 3.07 program. The gauge-including atomic orbital (GIAO) approach 28 was used to ensure gauge invariance of the result. The calculated chemical shifts were transformed to the -scale as the difference between the isotropic part of magnetic shielding tensor and that of TMS.
Journal of the American Chemical Society, 1985
The observations reported here demonstrate the existence of solids containing magnesiate ions and strongly suggest that stable solutions containing significant concentrations of such ions can readily be formed. ____ ~ (19) NMR observations indicated no significant interaction between Et,Mg and 15-crown-5 in tetrahydrofuran but partial formation of 1:l and 2:l (which could perha s have been 3:l) complexes in diethyl ether.2 Parlittle change on addition of the crown ether, we assumed that "ate" species are formed only in small amounts and that the changes in chemical shifts observed in diethyl ether resulted from coordination of oxygens of the crown ether to intact Et,Mg. Such coordination presumably was not significant in tetrahydrofuran because oxygens of 15-crown-5 could not compete effectively with those of tetrahydrofuran. We have now observed, however, that the IH NMR spectra of some solutions formed by adding 15-crown-5 to a benzene solution of Np,Mg show two sets of absorptions for the neopentyl groups consistent with the formation in the noncoordinating solvent of significant amounts of NpMg+(crown) and of magnesiate anions and leaves less certain the identity of the species responsible for the NMR shifts observed for diethyl ether solutions. ticularly since IH and I P C NMR absorptions of the ethyl groups underwent Acknowledgment. W e are grateful to the National Science Foundation for support of this research and for aiding in the purchase of the N M R spectrometers. We thank Professor Lloyd Jackman for numerous helpful discussions and Alan Freyer for obtaining the high-field N M R spectra.
Applied Spectroscopy, 1986
The 60 MHz 'H NMR spectra of racemic vinclozolin, 1, have been studied at 28 ° in CDCI~ solution with the achiral reagent tris(6,6,7,7,8,8,8heptuflooro-2,2-dimethyl-3,5-octanedionato)europium(III), 2, and the chiral reagents tris[3-(triflnoromethylhydroxymethylene)-d-camphorato] europium(III), 3, and tris[3-(heptafluoropropylhydroxymethylene)d-camphorato]enropium(IIl), 4. Reagent 3 produced only small lanthanide-induced shifts and no observable enantiomeric shift differences, AA~, with 3:1 molar ratios as high as 1.40. In contrast, chiral reagent 4 produced substantial AA~ for the proton, H B, at C-2 of the ethenyl group syn to the oxazolidinedione ring and smaller AA~ for the anti proton, Hp' at the above carbon and for the CH3. With a 4:1 molar ratio of 0.581, AA~ of 7.0 Hz was seen for Hp. A 4:1 ratio of about 0.41 should be optimum for optical purity determinations; as little as 5% of the minor enantiomer should be detectable. Index Headings: Analysis for optical purity of vinclozolin; Analytical methods; NMR; Achiral and chiral lanthanide shift reagents; Lanthanide shift reagents; Optical purity of vinclozolin; Vinclozolin.
Journal of Organometallic Chemistry, 2010
Reaction of 2-(2 0 ,6 0-diethylphenylazo)-4-methylphenol (L 2) with [Ir(PPh 3) 3 Cl] afforded two organoiridium complexes 3 and 4 via C-H bond activation of an ethyl group in the arylazo fragment of the L 2 ligand. In both the complexes the azo ligand binds to iridium as a dianionic tridentate C,N,O-donor. Two triphenylphosphines and a hydride (in the case of complex 3) or chloride (in the case of complex 4) are also coordinated to the metal center. A similar reaction of [Ir(PPh 3) 3 Cl] with 2-(2 0 ,6 0-diisopropylphenylazo)-4-methylphenol (L 3) yielded another organoiridium complex 5, where migration of one iso-propyl group from its original location (say, the 2 0 position) to the corresponding third position (say, the 4 0 position) took place through CC bond activation. In this complex the modified azo ligand binds to iridium as a dianionic tridentate C,N,O-donor. Two triphenylphosphines and a hydride are also coordinated to the metal center. The structures of complexes 3 and 4 have been optimized through DFT calculations. The structure of complex 5 has been determined by X-ray crystallography. All the complexes show characteristic 1 H NMR signals and intense transitions in the visible region. Cyclic voltammetry on all the complexes shows an oxidation within 0.66-1.10 V vs SCE, followed by a second oxidation within 1.15-1.33 V vs SCE and a reduction within À0.96 to À1.07 V vs SCE.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 202 (2018) 146–
Pyrazoline are widely being studied due to their potential applications in chemical field. Herein, five pyrazolines compounds were synthesized and characterized spectroscopically using nuclear magnetic resonance techniques ( 1 H NMR & 13 C NMR) to determine the structures of molecules along-with UV-Visible and infrared (FT-IR) studies for additional spectroscopic support in characterization of entitle synthesized molecules. Unit cells, specific space groups, bond lengths, bond angles and hydrogen bonding interactions were determined by the x-ray diffraction studies. Further, computational study of compounds with B3LYP/6-311 + G(d,p) level were carried out to explore optimized geometry, spectroscopic data for FT-IR, frontier molecular orbitals (FMOs) and non-linear optical (NLO) parameters. While, UV-Vis spectral were performed by TD-DFT/B3LYP/6-311 + G(d,p) level. The experimental results of spectroscopic and single crystal studies were compared and found in good agreement with the computational. The global reactivity parameters have been calculated with the help of the energy of FMOs. The order for the total first and second order hyperpolarizabilities of 1-5 is found in the following orders: 1 N 4 N 3 N 5 N 2 and 1 N 4 N 5 N 2 N 3 respectively. Overall, greater NLO response than urea molecule prove that investigated molecules are excellent candidate for NLO applications.
Electronic spectra of ?,?-unsaturated ketones ? Indole derivatives
Chemistry of Heterocyclic Compounds, 1972
The electronic spectra of (3-indolyl)-, (1-methyl-3-indolyl)-, and (6-nitro-3-indolyl)-substituted a,fi-unsaturated ketones were measured and interpreted. 3-Indolyl and N-methyl-3-indolyl substituents have a considerable bathochromic effect as compared with the phenyl group in the investigated systems as a consequence of the electron-donor effect, which surpasses that for 4-anisyl, 2,4-dimethoxyphenyl, 2-furyl, 2-thienyl, and 2-selenienyl and differs only slightly from 2-pyrrolyl. The introduction of electron-donor substituents into the p position of the benzene ring of 1-(3-indolyl)-3-phenyl-l-propenone causes a red shift of the long-wave absorption band, the difference in frequencies of which correlates with the Hammett ~ substituent constants. Except for compounds containing a nitro group, 1-(3indolyl)-3-aryl-3-propenones and their N-methyl derivatives fluoresce well in alcohol with max > 475 nm.