Efficient solid-phase synthesis of quinazoline-2,4-diones with various substituents on aromatic rings

We have developed a method for the solid-phase synthesis of quinazoline-2,4-diones with various substituents on the aromatic ring. Although there have been numerous reports of the solid-phase synthesis of quinazoline-2,4-diones, they were not applicable to the synthesis of the quinazoline-2,4-diones with electron-withdrawing substituents on the aromatic ring. Considering the poor nucleophilicity of the amino group of anthranilic acids, coupling of anthranilic acids to solid-supported amines was investigated without protecting the amino group. Various anthranilamides were prepared using anthranilic acids with electron-withdrawing substituents because a wide range of anthranilic acids are commercially available. These anthranilamides were successfully cyclized with carbonyldiimidazole to give quinazoline-2,4-diones with high purity.     

The effect of substituents in macrocyclic polyethers containing aromatic rings on ion-selective electrode properties

Ion-selective electrodes, containing derivatives of crown ethers with aromatic rings, have been investigated. The electrodes were characterized by determining their detection limits and selectivity coefficients. Thet-butyl derivative of naphtho-15-crown-5 was found to exhibit the best properties (L _d =1×10^–5,K _Na/K=6×10^–4).     

Influence of substituents on the kinetics of epoxy/aromatic diamine resin systems

Eleven different epoxy/diamine systems, including tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM), triglycidyl p‐aminophenol (TGAP), and diglycidyl ether of bisphenol A (DGEBA) with 4,4′‐diaminodiphenylsulfone (DDS), diethyltoluenediamine (DETDA), dimethylthiotoluenediamine (DMTDA), and meta‐phenylenediamine (m‐PDA), were studied with near‐infrared spectroscopy at different temperatures. The reactivities of the epoxies were determined and found to be in the following order when reacted with the same amine: DGEBA > TGAP > TGDDM. When the primary amine was reacted with the same epoxy, the order was DETDA > DDS > DMTDA; for the secondary amine, the order was DETDA > DMTDA > DDS. The relative reaction rates of the secondary amine to the primary amine were compared and discussed in terms of the structural differences and the corresponding substitution effect. It was concluded that the increase in the secondary amine reactivity of DETDA and DMTDA was caused by the deconjugation of the benzene‐ring π electrons from the lone pair on the N atom. The overall order of the secondary amine relative reactivity was DMTDA > DETDA > DDS for the same epoxy and TGDDM > TGAP > DGEBA for the same amine. The m‐PDA systems had no significant positive or negative substitution effects. Molecular orbital calculations were performed, and the results showed the most significant deconjugation effect in the secondary amine of DETDA. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3143–3156, 2004     

Influence of lateral substituents on thermal behavior and solubility of aromatic LC-polyesters

Structure - property relations of substituted para-linked aromatic homopolyesters are reported. Thermotropic liquid-crystalline substituted poly (1,4-phenylene terephthalate)s with phase transition temperatures less than 230 °C and good solubility in common organic solvents have been synthesized. If a noncoplanar 2,2′-disubstituted biphenylene moietyis combined with a monosubstituted phenylene moiety with sufficient bulky substituent, polyester with similar properties were obtained. Although these polyesters are soluble up to high concentrations, no lyotropic liquid-crystalline behavior was observable.     

Electronic effects from σ-C3H4MX group substituents in aromatic rings

Conclusions The m- and p-fluorophenylallyl derivatives of Hg and Sn have been prepared, and study made of the properties of the -allyl C₃H₄MX (M=HgCl, SnPh₃) group as a substituent in the aromatic ring.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 328–331, February, 1979.     

Influence of substituents on the separation of aromatic esters by bonded-phase charge transfer liquid chromatography

Summary The separation of aromatic esters has been studied on acceptor bonded phases. It is likely that donor-acceptor complex (DAC) formation occurs between the acceptor phase and the electrons of the carbonyl groups. The influence of substituents attached to the aromatic rings and the role of the alkyl chains of phthalates on retention are discussed.     

Through-bond and through-space interactions of substituents and the nonlinearity of X-C≡Y Linkages

Ab initio SCF calculations using the split valence basis sets 3–21G, 4–21G, 4–31G, 5–31G, and 3–321G, which were augmented by a set of polarization functions on the nonhydrogen atoms, were performed on a series of propynes, nitriles, isonitriles, and geminal dinitriles. Substituent effects on the structures of these molecules have been interpreted via appropriate concepts. In contrast to widespread opinion, the CC triple bond may be highly sensitive to effects of substituents, particularly when these effects are associated with -bonding interaction. This is reflected, for instance, by the appreciable contraction of the CC bond length in 1 -fluoropropyne (1 -FP) of 1.173 Å in comparison to the same bond in cyanopropyne, 1.183 Å. One of the interesting results of the present work is the markedly short C-F bond distance of 1.275 Å in 1-FP. The most acceptable rationale for this bonding behavior is provided by electrostatic arguments. The geometric results of both F₂C(CN)₂ and CF₃NC, particularly the short C-F bond distance of 1.323 Å and 1.306 Å, respectively, indicate the presence of fluorine negative hyperconjugation (anomeric effect). The characteristic nonlinearity of the C-CN chain in several geminally substituted dinitriles, YC(CN)₂, has been discussed. It appears that a relationship exists between the direction of bending of the C-CN moieties and the electronegativity of Y.     

Influence of substituents in pyrrole rings on electronic structure and molecular electrostatic potentials of porphyrins

The distributions of the molecular electrostatic potential in the central cavities of the free bases protoporphyrin IX, mesoporphyrin IX, etioporphyrin III and of their mono- and dianions have been calculated. An analysis has been made of the influence of substituents in the pyrrole rings of the investigated porphyrins on the potential distribution in their central cavities and the possible mechanism for addition of protons to the appropriate dianions.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 3, pp. 335–339, May–June, 1988.     

Influence of lateral methyl and terminal substituents on the mesophase behaviour of four rings azo-ester liquid crystal compounds

ABSTRACT

The effect of introducing a lateral methyl substitution into the previously investigated laterally neat four-ring analogues, 4-substituted phenylazo phenyl 4?-(4?-alkoxyphenylazo) benzoates (In_a–e), on their mesophase behaviour was investigated for the newly prepared five homologous series of 4-substituted phenylazo phenyl 4?-(3?-methyl-4?-alkoxyphenylazo) benzoates (IIn_a–e). Within each homologous series, the alkoxy group varies between 6, 8, 10, 12, 14, and 16 carbons, while the substituent, X, is a polar group that alternatively changes between the electron-donating (CH₃O and CH₃) groups, and the electron-withdrawing (Br and NO₂) groups, including the unsubstituted homologues (IIn_c). Their mesophase stabilities were determined by DSC and phases identified by PLM. The results showed that independent of the alkoxy-chain length or the polarity of the substituent X, the nematic phase is predominant with relatively high stability and wide temperature ranges. All compounds show a good thermal stability in the mesophases domain, except the nitro and Br substituted derivatives bearing short alkoxy chain length. Comparison of the mesophase behaviour was also made between the present series and corresponding three-ring laterally CH_3-substituted azo/ester analogues. UV-vis absorption spectra revealed that derivatives with electron donating or an electron withdrawing groups exhibited redshifts of the π→π* transition compared with unsubstituded derivative.     

Influence of substituents on hydrogenation of nitro groups in aromatic hydrocarbons catalyzed by rhenium thiocomplexes

Homogeneous hydrogenation studies of (NO₂)_1–2–C₆H_3–4–L nitro compounds (where L=–H,–NH₂,–COOH,–CHO,–OH,–CH₃ and –CH=CH–COOH) catalyzed by Re₂S₆TThio₃Cl₂ in dimethylformamide solutions at and T=343 K, have revealed that the reaction is enhanced by electron-acceptor substitutents and hindered by electron-donor ones.

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(NO₂)_1–2–C₆H_3–4–L, L=–H,–NH₂,–COOH,–CHO,–OH,–CH₃,–CH=CH–COOH, Re₂S₆Thio₃Cl₂ 343 . , .

     

Metathesis of allylsilanes with aromatic substituents

Conclusions The feasibility was demonstrated for the efficient metathesis of phecyltolyl- and benzylallylsilanes on an alumorhenium catalyst promoted by tetrabutyltin. The metathesis of aryldimethylallylsilanes or aralkyldimethylallylsilanes is a preparative method for the synthesis of 1,4-bis(aryldimethylsilyl)-2-butenes or 1,4-bis(aralkyldimethylsilyl)-2-butenes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2121–2123, September, 1984.     

Influence of the aromatic ring substituents on phase equilibria of vanillins in binary systems with CO2

Solid–liquid phase transitions of vanillin, ethylvanillin, o-vanillin and o-ethylvanillin in presence of compressed CO₂ were determined with the modified capillary method. Furthermore, the solubilities of the above mentioned vanillins in supercritical CO₂ were measured at 313.2, 333.2 and 353.2 K and in the pressure range 8–30 MPa using a static–analytic method. The experimental equilibrium solubility data have been fitted to the Peng–Robinson equation in combination with two parameter van der Waals mixing rules and binary parameters were determined from the best fit. Results showed that the phase equilibria of vanillins in dense CO₂ are influenced by the position of the hydroxyl group bound to the aromatic ring. Under the pressure of CO₂ the melting point depression and also the solubility of both o-vanillins was higher than those of p-vanillins. Oppositely, the alchoxy group (methoxy or ethoxy) showed no significant influence on the solubility of vanillins.     

N-Phosphano nitrogen-containing five-membered aromatic chiral α-sulfoxides as new chiral ligands in asymmetric palladium-catalyzed allylic alkylation: stereoelectronic effects of the substituents on the aromatic rings

New chiral ligands, N-diphenylphosphano nitrogen-containing five-membered aromatic compounds bearing chiral sulfinyl groups as the sole chiral source has been developed. The structure of a palladium intermediate derived from the new chiral sulfoxide ligand was determined as a palladium complex with a five-membered chelate ring formed by coordination of the phosphano group and the sulfinyl sulfur atom involved. The stereoelectronic effects of substituents on the aromatic rings are discussed.     

Porphyrins with exocyclic rings. Part 21: Influence of pyrrolic and carbocyclic ring alkyl substituents on the synthesis of porphyrins bearing six-membered exocyclic rings

A series of 5-substituted 4,5,6,7-tetrahydroindoles were prepared by reacting 4-substituted cyclohexanones with phenylhydrazones derived from esters of acetoacetic acid under Knorr-type reaction conditions. Related 6,6-dimethyltetrahydroindoles were also prepared by reacting dimedone with oximes by the Knorr pyrrole syntheses, followed by selective reduction of the remaining ketone moiety with diborane. The substituted tetrahydroindoles were regioselectively oxidized with lead tetraacetate to give the related 7-acetoxy derivatives, and these reacted with 5-unsubstituted pyrrole esters to give pyrrolyltetrahydroindoles. In one case, a bromo substituent was used to protect the β-position of the pyrrole reactant. Cleavage of the benzyl ester protective groups with hydrogen over Pd/C, which also removes the bromo-protective group, gave four dipyrrole carboxylic acids. These were condensed with a dipyrrylmethane dialdehyde using the MacDonald ‘2+2’ condensation to give substituted porphyrins with six-membered exocyclic rings. These structures are useful for comparison to porphyrin samples found in organic-rich sediments such as oil shales and petroleum. The presence of methyl substituents on the six-membered ring for the tetrahydroindole precursors slightly decreases the yields for porphyrin synthesis, and this effect is enhanced when the system becomes more sterically crowded due to the presence of an ethyl group of the adjacent pyrrole ring. 5-Alkyl substituted tetrahydroindoles were also converted to tetrapropanoporphyrins via a cyclotetramerization procedure. The alkyl substituents again decreased the yields, although 5-alkyl substituents were found to have a far less deleterious effect than 6-alkyl groups. In addition to providing samples to help assign the vibrational spectra of geoporphyrin samples, these results demonstrate that highly substituted porphyrin systems can be prepared from tetrahydroindole derivatives.     

New phosphaalkenes with small rings as substituents

Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1324–1325, July, 1993.     

Catalytic activity tuning of a biomimetic HO-FeV=O oxidant for methane hydroxylation by substituents on aromatic rings: theoretical study

HO-(TPA)FeV=O (TPA = tris(2-pyridylmethyl)amine) has been proposed in the literature as the key high-valent iron-oxo intermediate involved in alkane hydroxylation. Here the structure of this species is investigated theoretically in the framework of density functional theory (DFT). A detailed electronic structure analysis leads to the presumption that the properties of the FeV=O bond can be modified by introducing substituents to the aromatic rings of TPA and thus the reactivity of HO-(TPA)FeV=O for the hydrogen atom abstraction of methane hydroxylation can be tuned on the quartet potential energy surface. The validity of our presumption is verified by DFT calculations. According to the rebound mechanism, the H-abstraction step is examined by using five complexes with TPA and TPA-derivative ligands and the corresponding reaction energies and energy barriers are obtained and compared with each other. The results are fully in agreement with our qualitative model, showing that electron-withdrawing groups are able to lower the barrier and facilitate the reaction, whereas the electron-donating groups increase the barrier and reduce the reactivity.