COOEt Group Research Articles

Tuning colorful luminescence of iridium(III) complexes from blue to near infrared

Five cyclometalated Ir(III) complexes with high phosphorescence efficiencies have been synthesized from 1,3-bis(1-propyl-1H-benzo[d]imidazol-2-yl)benzene (Pro-MBImB) or 2-(2,4-Difluorophenyl)pyridine (Fppy) based ligands with different ancillary ligands. It was found that these complexes have a wide range of emitting wavelength, covering the whole visible region, with moderately long lifetime (81–2159 ns) and high quantum yield (75–89%). Especially, the introduction of electron withdrawing −COOEt group onto the ancillary ligand extends the emission wavelength and affords good red-light emitting properties, and the obtained CIE (Commission Internationale de L'Eclairage) coordinates of (0.69, 0.31) in complex 2 are close to the standard red light and approaching near infrared region.

Insights on conformation in the solid state: a case study – s-cis and/or s-trans crystallization of 5(3)-aryl-3(5)-carboxyethyl-1-tert-butylpyrazoles

The conformation adopted by COOEt group in solid state were influenced by supramolecular environment and intramolecular interaction for 1,3- and 1,5-regioisomers, respectively.

A Cross-Coupling Synthesis of Functionalised Biaryls Using Knochel-Type Organozinc Reagents and a Pyridine Enhanced Palladium Catalyst

A variety of functionalised biaryls were synthesised on the 20–30 mmol scale by using Knochel type organozinc reagents (organozinc reagents prepared from aryl halides, Zn powder and LiCl) catalysed by PEPPSI (a pyridine enhanced palladium catalyst). The protocol enabled the Negishi reactions to proceed in a smooth, rapid and mild way to give the corresponding products in excellent yields (80 ~ 96%). Sensitive functional groups, such as CN and COOEt groups, were tolerated in the coupling reaction.

Substituent effects in trans-p,p'-disubstituted azobenzenes: X-ray structures at 100 K and DFT-calculated structures.

The crystal and molecular structures of two para-substituted azobenzenes with π-electron-donating -NEt2 and π-electron-withdrawing -COOEt groups are reported, along with the effects of the substituents on the aromaticity of the benzene ring. The deformation of the aromatic ring around the -NEt2 group in N,N,N',N'-tetraethyl-4,4'-(diazenediyl)dianiline, C20H28N4, (I), may be caused by steric hindrance and the π-electron-donating effects of the amine group. In this structure, one of the amine N atoms demonstrates clear sp(2)-hybridization and the other is slightly shifted from the plane of the surrounding atoms. The molecule of the second azobenzene, diethyl 4,4'-(diazenediyl)dibenzoate, C18H18N2O4, (II), lies on a crystallographic inversion centre. Its geometry is normal and comparable with homologous compounds. Density functional theory (DFT) calculations were performed to analyse the changes in the geometry of the studied compounds in the crystalline state and for the isolated molecules. The most significant changes are observed in the values of the N=N-C-C torsion angles, which for the isolated molecules are close to 0.0°. The HOMA (harmonic oscillator model of aromaticity) index, calculated for the benzene ring, demonstrates a slight decrease of the aromaticity in (I) and no substantial changes in (II).

ChemInform Abstract: Reactions of Perfluorobenzocycloalkenes with Ethyl Cyanoacetate and Methyllithium and Some Transformations of the Products.

Reactions of perfluorobenzocycloalkenes (ArFF) with methyllithium and ethyl cyanoacetate involved replacement of fluorine atoms in positions 3 and 4 of perfluorocyclobutabenzene, position 5 of perfluoroindan, and position 6 of perfluorotetralin by CH3 and CH(CN)COOEt groups. Hydrolysis of the resulting esters ArFCH(CN)COOEt gave the corresponding perfluoroarylacetic acids ArFCH2COOH which were converted into dichloroacetyl chlorides ArFCCl2COCl by treatment with PCl5. The reaction of ArFCCl2COCl with SbF5 produced trifluoromethyl derivatives ArFCF3. Decarboxylation of ArFCCl2COOH in DMF afforded dichloromethyl derivatives ArFCCl2H which reacted with CsF on heating to form difluoromethyl analogs ArFCF2H.

Reactions of perfluorobenzocycloalkenes with ethyl cyanoacetate and methyllithium and some transformations of the products

Reactions of perfluorobenzocycloalkenes (ArFF) with methyllithium and ethyl cyanoacetate involved replacement of fluorine atoms in positions 3 and 4 of perfluorocyclobutabenzene, position 5 of perfluoroindan, and position 6 of perfluorotetralin by CH3 and CH(CN)COOEt groups. Hydrolysis of the resulting esters ArFCH(CN)COOEt gave the corresponding perfluoroarylacetic acids ArFCH2COOH which were converted into dichloroacetyl chlorides ArFCCl2COCl by treatment with PCl5. The reaction of ArFCCl2COCl with SbF5 produced trifluoromethyl derivatives ArFCF3. Decarboxylation of ArFCCl2COOH in DMF afforded dichloromethyl derivatives ArFCCl2H which reacted with CsF on heating to form difluoromethyl analogs ArFCF2H.

10.1007/s11178-008-2020-9

Acid-catalyzed reaction of trifluoromethanesulfonamide with paraformaldehyde in ethyl acetate led to the formation of oxymethylated products that did not form in the reaction carried out in sulfuric acid. Following products were obtained: 5-trifluoromethylsulfonyl-1,3-dioxazinane, 3,7-bis-(trifluoromethylsulfonyl)-1,5,3,7-dioxadiazocane, and a complex of trifluoromethanesulfonamide with 2,4,8,10-tetraoxospiro[5,5]undecene, 1:1. The spiroring resulted from the cyclization of pentaerythritol under the action of formaldehyde. The pentaerythritol formed in its turn by oxymethylation of the methyl group of ethyl acetate with paraformaldehyde followed by the reduction of the COOEt group into CH2 OH by the formaldehyde.

Theoretical studies on pyrimidine substituent derivatives as dual inhibitors of AP-1 and NF-κB

Theoretical studies on the three-dimensional (3D) quantitative structure-activity relationship (QSAR) and mechanisms of action of a series of pyrimidine substituent derivatives as dual inhibitors of AP-1 and NF-kappaB were carried out using comparative molecular field analysis (CoMFA) and docking methods. The established 3D-QSAR model exhibits a satisfying statistical quality and prediction ability. Docking results show somewhat lower average values of the flexible and rigid energy scores in the chosen binding sites. The docking analysis offers appropriate orientations and conformations of these compounds at the binding sites to both AP-1 and NF-kappaB in good agreement with the 3D-QSAR model from CoMFA. The combined CoMFA and docking study suggests the following substituent selections: substituent R(2) should be a kind of H-N-thienyl or CH(3)-N-thienyl group; substituent R(5) should be a kind of COO-tBu or COOEt group; and substituent R(4) should be a CH(2)CH(3) or 2-thienyl group. The docking analysis also shows that the binding sites fall just at the joint regions between AP-1 (or NF-kappaB) and DNA, where these compounds can effectively prevent free AP-1 and NF-kappaB from binding to DNA, and this may be the reason that derivatives with pyrimidine substituents have an inhibition function. In addition, a very interesting finding was that the binding sites of both AP-1 and NF-kappaB have a common structural characteristic, thereby providing a reasonable explanation for the dual inhibition functions of these compounds towards both AP-1 and NF-kappaB. These theoretical results help to deepen our understanding of the inhibition mechanism of these pyrimidine substituent derivatives, and will aid in directing further drug-molecular design.

Oxymethylation of trifluoromethanesulfonamide with paraformaldehyde in ethyl acetate

Acid-catalyzed reaction of trifluoromethanesulfonamide with paraformaldehyde in ethyl acetate led to the formation of oxymethylated products that did not form in the reaction carried out in sulfuric acid. Following products were obtained: 5-trifluoromethylsulfonyl-1,3-dioxazinane, 3,7-bis-(trifluoromethylsulfonyl)-1,5,3,7-dioxadiazocane, and a complex of trifluoromethanesulfonamide with 2,4,8,10-tetraoxospiro[5,5]undecene, 1:1. The spiroring resulted from the cyclization of pentaerythritol under the action of formaldehyde. The pentaerythritol formed in its turn by oxymethylation of the methyl group of ethyl acetate with paraformaldehyde followed by the reduction of the COOEt group into CH2 OH by the formaldehyde.

Development of New Reactions of Fluorine Compounds Using a Rhodium Catalyst

Novel fluoroalkylated products where a CF(2)COOEt group was introduced at the alpha-position of alpha,beta-unsaturated ketones or the Reformatsky-type products have been obtained selectively by the reaction of BrCF(2)COOEt and alpha,beta-unsaturated ketones with Et(2)Zn in the presence of RhCl(PPh(3))(3) depending on the solvents. Furthermore, the novel alpha-fluoroalkylated products could synthesize by using various halofluoroalkyl compounds (R(f)-X) instead of BrCF(2)COOEt. On the other hand, this Reformatsky-type reaction by imines gave difluoro-beta-lactams or 3-amino-2,2-difluorocalboxylic esters without or with MgSO(4) . 7H(2)O, selectively.

Contrast‐enhanced MRI with new biodegradable macromolecular Gd(III) complexes in tumor‐bearing mice

The structures of polydisulfide-based biodegradable macromolecular Gd(III) complexes were modified to improve their in vivo retention time and MRI contrast enhancement. Steric hindrance was introduced around the disulfide bonds to control their access to free thiols in order to alter the degradation rate of the copolymers. Two new macromolecular agents, (Gd-DTPA)-cystine copolymers (GDCP) and (Gd-DTPA)-cystine diethyl ester copolymers (GDCEP), were prepared. Both agents were readily degraded in vitro and in vivo by the disulfide-thiol exchange reaction, but at a slow rate. The introduction of COOH and COOEt groups slowed down the degradation of the copolymers in the incubation with 15 microM cysteine. Metabolic degradation products were identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry in the urine samples from rats injected with the agents. The T(1) relaxivity (r(1)) was 5.43 mM(-1)s(-1) for GDCP, and 5.86 mM(-1)s(-1) for GDCEP, respectively, at 3T. MRI contrast enhancement of both agents was studied in nude mice bearing MDA-BM-231 human breast carcinoma xenografts, on a Siemens Trio 3T scanner. The modified agents resulted in more significant contrast enhancement in the blood pool and tumor periphery than (Gd-DTPA)-cystamine copolymers (GDCC) and a low-molecular-weight control agent, Gd-(DTPA-BMA), at a dose of 0.1 mmol-Gd/kg. The results demonstrate that the structural modification of the biodegradable macromolecular Gd(III) complexes resulted in a relatively slow degradation of the macromolecules and significantly improved in vivo contrast enhancement. The modified agents show promise for use in investigations of blood pool and cancer by contrast-enhanced (CE) MRI.

Kinetics and Mechanism of the Addition of Benzylamines to Ethyl-α-cyanocinnamates in Acetonitrile

Nucleophilic addition reactions of benzylamines (BA; <TEX>$XC_6H_4CH_2NH_2$</TEX>) to ethyl-<TEX>${\alpha}$</TEX>-cyanocinnamates (ECC;<TEX>$YC_6H_4CH$</TEX>=C(CN)COOEt) have been investigated in acetonitrile at <TEX>$30.0^{\circ}C$</TEX>. The rate is first order with respect to BA and ECC. The rate is slower than that expected from the additive effect of <TEX>${\sigma}^-$</TEX> or <TEX>$R^-$</TEX> for the activating groups (CN and COOEt). Natural. bond orbital <TEX>${\pi}^{\ast}_{c=c}$</TEX> calculations show that the contribution of COOEt group may not be fully effective despite the coplanar molecular structure. The selectivity parameters including the cross-interaction constant (<TEX>${\rho}_{xy}$</TEX> = -0.22) indicate that the addition occurs in a single step. The kinetic isotope effects (<TEX>$k_H/k_D$</TEX>=2.5-2.8) involving deuterated BA (<TEX>$XC_6H_4CH_2ND_2$</TEX>) nucleophiles and activation parameters (<TEX>${\Delta}H^{\neq}=4{\sim}6\;kcal\;mol^{-1};{\Delta}S^{\neq}=-45{\sim}-52\;e.u.$</TEX>) suggest a cyclic transition state in which N-<TEX>$C_{\alpha}$</TEX> and H-<TEX>$C_{\beta}$</TEX> bonds are formed concurrently.

Reversible C ⇆ N migration of the ethoxycarbonyl group in the reactions of pyridinium and isoquinolinium ylides derived from malonic ester with isocyanates

AbstractPyridinium and isoquinolinium ylides (7 and 12) derived from malonic ester react in an unusual manner with isocyanates giving the new pyridinium ylide (9) and the new isoquinolinium ylide (14). C → N Migration of the COOEt group takes place at room temperature, but, at an elevated temperature, reverse N → C migration of the COOEt group proceeds and ylides 9 and 14 are reconverted into the starting ylides 7 and 12, respectively. © 2002 John Wiley &amp; Sons, Inc. Heteroatom Chem 13:36–45, 2002; DOI 10.1002/hc.1104

Exocyclic push–pull conjugated compounds. Part 1. Theoretical study of the effect of ring size on the structure, electronic properties and rotational barriers of cyclic analogoues of 1,1-diamino-2,2-dicyanoethylene

An MO theoretical ab initio study was performed on 2-exo-methylene push–pull derivatives having as donor groups nitrogen atoms, components of a heterocyclic ring, and as acceptors CN and COOEt groups. Five-, six- and seven-membered ring derivatives were considered. Calculations were also performed on a number of push–pull ethylenes whose experimental properties were reported in the chemical literature in order to test the soundness of the conclusions from theoretical approaches. The physical properties calculated for the latter molecules were compared with known experimental values, in order to check the predictive ability of the theoretical approaches employed. Geometrical features and torsional barriers in solution are satisfactorily reproduced. Results were obtained with different basis sets, second-order Møller–Plesset theory, in order to perform comparisons at different theoretical levels with a view to carrying out calculations in larger molecular systems. The widest range of comparisons between calculated values for the different molecules were carried out at the HF/6-31G∗//HF/6-31G∗ level. The origin of the torsional barrier for isomer interconversion as a function of the electronic properties of these molecules is discussed, in particular by examining the polarized character of the exo double bond. The role of the lone pairs of the nitrogen atoms in the push–pull mechanism is investigated, also in competition with an unsaturated bond within the ring. The different conjugation patterns that can be exploited within these molecules is examined within the donor–acceptor model and Natural Bond Orbital (NBO) theory. Empirical correlations are proposed in order to estimate dipole moments and absorption wavelengths for the family of push–pull olefins.

1H and13C NMR spectra of betaines, &gt;N+(CH2)nCOO−, and their hydrogen halides. Additivity rules for carbon-13 chemical shifts

The 1H and 13C chemical shifts of N-methylpiperidine betaines (1), C5H10N+(CH3)(CH2)nCOO−, and their derivatives C5H10N+(CH3)(CH2)nCOOH·X− (2) and C5H10N+(CH3)(CH2)nCOOC2H5·X− (3) with n = 1–5 were identified using two-dimensional homonuclear (1H) chemical shift correlation (COSY) and heteronuclear (1H, 13C) chemical shift correlation spectroscopy (H,C-COSY). The effects of the positively charged nitrogen and COO−, COOH, COOEt groups on the methylene protons in the tether groups [N+(CH2)nCOO] and the ring protons in 1, N-methylpyrrolidine betaines (4), pyridine betaines (6) and their hydrogen halides, were analysed. Empirical additivity rules for the 13C chemical shifts of tether C-1, C-2, C-3, C-4 and C-5 atoms for 1, 4 and 6 and their hydrogen halides were derived from the experimental results. The effect of N+ on the β carbon vary with the ring type. Copyright © 2000 John Wiley & Sons, Ltd.

Ethyl Pentaspiro[2.0.2.0.0.2.0.2.0.1]tetradeca-14-ylideneacetate, C18H22O2

The title molecule has a Z configuration at the exo-cyclic C=C double bond. The four-membered ring and the COOEt group are almost coplanar. The unusual distribution of bond lengths in the polycyclic system is a result of the electron-withdrawing effect of the COOEt group.

STRUCTURAL EFFECT IN FORKED CONJUGATIVE SYSTEMS——BIFURCATION-TYPE OF FORKED POLYENIC NITRILES,CARBOXYLIC ACIDS AND ESTERS

Five homologous series of bifurcate systems of aliphatic and aromatic polyenic cyano and carboxylic compounds have been prepared and studied. The electronic absorption spectra forthe series and the NMR chemical shifts for the methyl-, methylene- and beta-protons havebeen found to conform very well to the rule of homologous linearity. The mass spectra forthe α-cyano polyenic ester series show strong peaks for the fragments of M-COOEt but noneof M-CN, indicating that the CN group seems to be in stronger conjugation with the poly-enic chain than the COOEt group does. In all the forked series studided, a red shift in electronic spectra is brought about upon the introduction of an electron-attractive branching group, just like the case of introducing an electron-repelling substituent. This has been taken as an indication of the predominance of themolecular integrality over the group characteristics. By means of the method of similar triangles between a homologous line for a linearseries and that for the corresponding forked compounds, the equivalent △Ns for a branching group may be calculated with accuracy. Based on the value of this equivalent, the substituentnature of the structural effect of the branching group has been inferred. The electronic absorption maxima for four series of the forked compounds have been cal-culated by means of the extended homologous equation for the corresponding linear compounds.With an appropriate correction for the positional effect of the substituent equivalent, the cal-culated wavelengths agree generally with experimental data within ± 7nm.

Migration du groupe éthoxycarbonyle dans la transposition de Wagner‐Meerwein

Ethoxycarbonyl group migration in the Wagner‐Meerwein rearrangement.13 β‐Hydroxy‐esters have been treated with P2O5 in benzene at 80°. Olefin‐forming dehydration, when possible, was found to be the main reaction. When this is excluded, tertiary or benzylic hydroxy‐esters react in a manner most easily explained by migration of the COOEt group, thus avoiding the formation of α‐carbonyl‐carbenium ions. On the other hand, in primary hydroxy‐esters (incapable of direct olefin formation), phenyl and methyl groups migrate in preference to COOEt, indicating in this case a concerted reaction.