- Fixation of Carbon Dioxide with Diphenylcarbodiimide as a Model of Biotin Enzyme Active Site and a Weak Base: The Carboxylation of Fluorene under Mild Conditions
-
Carbon dioxide was directly fixed into fluorene in the presence of diphenylcarbodiimide (DPC) as a model of a biotin enzyme active site and potassium hydrogencarbonate.It was considered that not only carbon dioxide but also the hydrogencarbonate ion were the carbon source in the presence of DPC.Weak bases such as potassium acetate, potassium propionate, and potassium formate were also effective for carboxylation.
- Chiba, Koji,Tagaya, Hideyuki,Karasu, Masa,Ono, Tsuyoyuki,Saito, Masaru,Ashikagaya, Atsushi
-
-
Read Online
- Flash photolysis of 10-diazo-9(10H)-phenanthrenone in aqueous solution. Hydration of fluorenylideneketene and the fluorene-9-carboxylic acid keto-enol system
-
Flash photolysis of 10-diazo-9(10H)-phenanthrenone in aqueous solution was found to give two successively formed transient species and to produce fluorene-9-carboxylic acid as the major reaction product. These transients were identified, through solvent isotope effects and the form of acid-base catalysis, as fluorenylideneketene, formed by photo-Wolff reaction of the diazophenanthrenone, and fluorene-9-carboxylic acid enol, formed by hydration of this ketene. Analysis of the rate profile of the enol ketonization reaction produced the first and second ionization constants for the enol ionizing as an oxygen acid, pQ(a)(E) = 2.01 and pQ'(a)(E) = 9.61, respectively. The rate of enolization of fluorene-9-carboxylic acid was also determined, by bromine scavenging, and that, coupled with a literature value of the acidity constant of this acid, allowed evaluation of the two keto-enol equilibrium constants (pK(E) = 9.67 for interconverting un-ionized carboxylic acid and enol and pK'(E) = 8.24 for interconverting singly ionized acid and enol), and it also allowed evaluation of the two carbon acid acidity constants (pQ(a)(K) = 11.67 for ionization of the un-ionized carboxylic acid as a carbon acid and pQ'(a)(K) = 17.85 for ionization of its carboxylate ion as a carbon acid). (All acidity constants are concentration quotients applicable at ionic strength 0.10 M.) These keto-enol equilibrium constants and acid dissociation constants are large because of the enol and enolate ion stabilizing effects of the cyclopentadienyl ring of the fluorenyl group; this ring also makes fluorenylideneketene an unusually reactive substance.
- Andraos,Chiang,Kresge,Popik
-
-
Read Online
- Electrogenerated Sm(II)-Catalyzed CO2 Activation for Carboxylation of Benzyl Halides
-
Sm(II)-catalyzed carboxylation of benzyl halides is reported through the electrochemical reduction of CO2. The transformation proceeds under mild reaction conditions to afford the corresponding phenylacetic acids in good to excellent yields. This user-friendly and operationally simple protocol represents an alternative to traditional strategies, which usually proceeds through the C(sp3)-halide activation pathway.
- Bazzi, Sakna,Schulz, Emmanuelle,Mellah, Mohamed
-
supporting information
p. 10033 - 10037
(2019/12/24)
-
- CATALYST COMPONENT FOR OLEFIN POLYMERIZATION AND CATALYST CONTAINING CATALYST COMPONENT AND USE THEREOF
-
A catalyst component for olefin polymerization, comprising Mg, Ti, a halogen and an electron donor, wherein the electron donor is at least one unsaturated ring-substituted diacid ester compound. Also provided is a catalyst containing the catalyst component and the use of the catalyst in an olefin polymerization, e.g., propylene polymerization.
- -
-
Paragraph 0068
(2017/04/21)
-
- CATALYST COMPONENT FOR OLEFIN POLYMERIZATION AND APPLICATION THEREOF
-
Provided is a solid catalyst component for olefin polymerization, which comprises Mg, Ti, a halogen and an electron donor. The electron donor is selected from at least one of ring-substituted ether-acid ester compounds of the general formula (I). Also provided are a catalyst containing the solid catalyst component and the application of the catalyst in reactions of olefin polymerization, particularly in the reaction of propylene polymerization.
- -
-
Paragraph 0096
(2017/10/17)
-
- Ni-catalyzed carboxylation of C(sp2)- and C(sp3)-O bonds with CO2
-
In recent years a significant progress has been made for the carboxylation of aryl and benzyl halides with CO2, becoming convenient alternatives to the use of stoichiometric amounts of well-defined metal species. Still, however, most of these processes require the use of pyrophoric and air-sensitive reagents and the current methods are mostly restricted to organic halides. Therefore, the discovery of a mild, operationally simple alternate carboxylation that occurs with a wide substrate scope employing readily available coupling partners will be highly desirable. Herein, we report a new protocol that deals with the development of a synergistic activation of CO2 and a rather challenging activation of inert C(sp2)-O and C(sp3)-O bonds derived from simple and cheap alcohols, a previously unrecognized opportunity in this field. This unprecedented carboxylation event is characterized by its simplicity, mild reaction conditions, remarkable selectivity pattern and an excellent chemoselectivity profile using air-, moisture-insensitive and easy-to-handle nickel precatalysts. Our results render our method a powerful alternative, practicality and novelty aside, to commonly used organic halides as counterparts in carboxylation protocols. Furthermore, this study shows, for the first time, that traceless directing groups allow for the reductive coupling of substrates without extended π-systems, a typical requisite in many C-O bond-cleavage reactions. Taking into consideration the limited knowledge in catalytic carboxylative reductive events, and the prospective impact of providing a new tool for accessing valuable carboxylic acids, we believe this work opens up new vistas and allows new tactics in reductive coupling events.
- Correa, Arkaitz,Leon, Thierry,Martin, Ruben
-
supporting information
p. 1062 - 1069
(2014/02/14)
-
- Ni-catalyzed direct carboxylation of benzyl halides with CO2
-
A novel Ni-catalyzed carboxylation of benzyl halides with CO2 has been developed. The described carboxylation reaction proceeds under mild conditions (atmospheric CO2 pressure) at room temperature. Unlike other routes for similar means, our method does not require well-defined and sensitive organometallic reagents and thus is a user-friendly and operationally simple protocol for assembling phenylacetic acids.
- León, Thierry,Correa, Arkaitz,Martin, Ruben
-
supporting information
p. 1221 - 1224
(2013/03/14)
-
- The epimetallation and carbonation of carbonyl and imino derivatives: Epivanadation route to 2-amino and 2-hydroxy acids
-
The feasibility of hydrocarboxylating carbonyl and imino derivatives by the two-step process of epimetallation and carbonation has been demonstrated with the model substrates of 9-fluorenone and 9-fluorenone anil. With lithium vanadium dihydride as the epimetallating agent, such hydrocarboxylation has led to a 75% yield of 9-hydroxy-9-fluorenecarboxylic acid and a 65% yield of 9-(N-phenylamino)-9-fluorenecarboxylic acid, respectively. Some initial success in extending the scope of this reaction to other substrates, such as benzophenone, has been achieved by using other epimetallating agents, like the presumed LiV(CH3)2 and Ti(OPri)2. A brief review of the processes and organic synthetic applications of epimetallation and transfer epimetallation of C-C π-bonds is offered as background.
- Eisch, John J.,Fregene, Paul O.,Gitua, John N.
-
p. 4647 - 4653
(2008/03/12)
-
- Simultaneous pH-rate profiles applied to the two step consecutive sequence A→B→C: A theoretical analysis and experimental verification
-
The absorbance extremum method introduced to resolve the rate constant-reaction step ambiguity problem in two step consecutive reactions is applied to cases where the rate constant in each step is pseudo first order and dependent on catalyst concentration. In particular, acid and base catalyzed reactions of substrates in aqueous solution are examined. Resultant simultaneous pH-rate profile functions are treated in the context of the ambiguity problem and a detailed account of the possible interactions between pH-rate profiles is also given. The merits of this method include its general scope, its applicability to reactions for which it may be experimentally difficult to resolve the ambiguity assignment by other means, and its use of rate data acquired from original kinetic traces without requiring additional information. The theoretical analysis is verified and tested experimentally for the hydration of fluorenylideneketene in dilute aqueous perchloric acid solutions.
- Andraos, John,Lathioor, Edward C.,Leigh, William J.
-
p. 365 - 373
(2007/10/03)
-
- NITRATION OR CARBOXYLATION CATALYSTS
-
In the presence of an imide compound (e.g., N-hydroxyphthalimide) shown by the following formula (1): ???wherein R1and R2represent a hydrogen atom, a halogen atom, an alkyl group, an aryl group and a cycloalkyl group, and R1and R2may bond together to form a double bond, or an aromatic or non-aromatic ring, and Y is an O or OH, and n denotes 1 to 3;, a substrate is allowed to contact with at least one reactant selected from (i) a nitrogen oxide and (ii) a mixture of carbon monoxide and oxygen to be introduced with at least one functional group selected from a nitro group and a carboxyl group. The nitrogen oxide includes, for example, a compound represented by the formula NxOy(e.g., N2O3, NO2). The substrate includes, for example, a compound having a methine carbon atom (e.g., adamantane), a compound having a methyl group or a methylene group at an adjacent moiety of an aromatic ring. According to such reaction, the substrate can be efficiently nitrated or carboxylated even in a mild or moderate condition.
- -
-
-
- N-acyl sulfamic acid esters (or thioesters), N-acyl sulfonamides, and N-sulfonyl carbamic acid esters (or thioesters) as hypercholesterolemic agents
-
The present invention is directed to compounds useful for the regulation of cholesterol of Formula I, methods for using them and pharmaceutical compositions thereof, STR1 wherein X and Y are oxygen, sulfur, or (CR'R")n wherein n is 1 to 4; R is hydrogen, alkyl, or benzyl; R1 and R2 are phenyl, substituted phenyl, naphthyl, substituted naphthyl, an aralkyl group, an alkyl chain, adamantyl, or a cycloalkyl group.
- -
-
-
- Carboxylation of Active Methylene Compounds Using Anilide, Potassium Carbonate, and Carbon Dioxide
-
Active methylene compounds were effectively carboxylated with carbon dioxide in the presence of anilide (acetanilide or formanilide) and potassium carbonate at 20-40 deg C for 0.5-10 h.In the carboxylation of fluorene, a high yield (48percent) was obtained at 20 deg C for 4 h.The yield of carboxylic acid using 2,6-dimethylacetanilide was 8.9percent, and smaller than 26.6percent when using acetanilide at 20 deg C for 2 h, indicating the interference of a methyl group for the carboxylation.
- Chiba, Koji,Tagaya, Hideyuki,Karasu, Masa,Ishizuka, Masahiko,Sugo, Toshiyuki
-
p. 452 - 454
(2007/10/02)
-
- Lanthanoid Complex as a Novel Carbon Dioxide Carrier for the Carboxylation of Active Methylene Compounds under Mild Conditions
-
A lanthanoid complex, formed by the addition of a lanthanoid alkoxide to an isocyanate, serves as a novel carbon dioxide carrier for the rapid carboxylation of active methylene compounds under mild conditions.
- Abe, Hiroshi,Inoue, Shohei
-
p. 1197 - 1198
(2007/10/02)
-
- The Carboxylation of Active Methylene Compounds with Carbon Dioxide in the Presence of 18-Crown-6 and Potassium Carbonate
-
Active methylene compounds were carboxylated with the reagent system, 18-crown-6, potassium carbonate and carbon dioxide, in dimethyl sulfoxide at room temperature and atmospheric pressure.The concentration of the carbonate ion is important for carboxylation.
- Chiba, Koji,Tagaya, Hideyuki,Miura, Syunji,Karasu, Masa
-
p. 923 - 926
(2007/10/02)
-
- Photodecarboxylation of diarylacetic acids in aqueous solution: Enhanced photogeneration of cyclically conjugated eight π electron carbanions
-
The photodecarboxylation of a series of diarylacetic acids 1-6 has been studied in aqueous solution. The mechanism of these photodecarboxylations is shown to involve C-C bond heterolysis from the singlet excited state, giving rise to carbanion intermediates. Quantum yields for photodecarboxylation (Φd) are reported at several pH's. Fluorescence quantum yields and lifetimes are reported as a function of pH, and their behavior is consistent with reaction via the carboxylate ions. Rate constants of photodecarboxylation (kdc) are estimated and show a marked dependence on the number of π electrons in the internal cyclic array (ICA). The most reactive compound was suberene-5-carboxylic acid (1) (Φd = 0.60 ± 0.05; kdc ≈ = 6 × 109 s-1), which gives a carbanion intermediate of eight π (4n) electrons in the ICA. The least reactive system was fluorene-9-carboxylic acid (4) (πd = 0.042 ± 0.004; kdc = 8.8 × 106 s-1), which on decarboxylation gives rise to a carbanion with an ICA of six π (4n + 2) electrons. The observed reactivity trend in the excited state is the reverse of that observed in the ground state and appears to demonstrate further the utility of the "4n rule" for predicting the relative reactivity of photochemical reactions giving rise to cyclically conjugated, charged intermediates. The possible theoretical significance of these observations is discussed.
- Krogh, Erik,Wan, Peter
-
p. 705 - 712
(2007/10/02)
-
- Spiro-tricyclicaromatic succinimide derivatives
-
Disclosed are substituted or unsubstituted planar tricyclic fluorene or nuclear analogs thereof, spiro-coupled to a five-membered ring containing a secondary amide, and the pharmaceutically acceptable salts thereof. These compounds are useful, inter alia in the treatment of diabetes. Also disclosed are processes for the preparation of such compounds; pharmaceutical compositions comprising such compounds; and methods of treatment comprising administering such compounds and compositions when indicated for, inter alia, long term, prophylactic treatment of the diabetes syndrome. A particularly preferred class of compounds comprise difluoro-dialkoxy substituted spiro-(9H-fluorene-9,4'-imidazolidine)-2,40 ,5-diones.
- -
-
-
- The Carboxylation of Active Methylene Compounds with Carbon Dioxide in the Presence of Diphenylcarbodiimide and Potassium Carbonate
-
Active methylene compounds were effectively carboxylated with carbon dioxide in the presence of diphenylcarbodiimide (DPC) as a biotin model and potassium carbonate.Fluorene was carboxylated even under a nitrogen atmosphere in the presence of DPC, indicating that a carbonate ion was the carbon source.The reaction occured even in the presence of water.It was considered that reaction intermediates are stable to water and that the concentration of the carbonate ion is important for carboxylation.
- Chiba, Koji,Tagaya, Hideyuki,Karasu, Masa,Ono, Tsuyoyuki,Hashimoto, Kazumi,Moriwaki, Yasusi
-
p. 966 - 970
(2007/10/02)
-
- The Carboxylation of Active Methylene Compounds with Diphenylcarbodiimide and Potassium Carbonate
-
Active methylene compounds were carboxylated by employing the reagent system, diphenylcarbodiimide and potassium carbonate, in dimethyl sulfoxide at room temperature and atmospheric pressure.The reaction proceeded even in the absence of carbon dioxide, but the carboxylation easily proceeded in carbon dioxide atmosphere.
- Chiba, Koji,Tagaya, Hideyuki,Karasu, Masa,Ono, Tsuyoyuki,Kugiya, Masashi
-
-
- Spiro-tricyclicaromatic succinimide derivatives
-
Disclosed are substituted or unsubstituted planar tricyclic fluorene or nuclear analogs thereof, spiro-coupled to a five-membered ring containing a secondary amide, and the pharmaceutically acceptable salts thereof. These compounds are useful, inter alia, in the treatment of diabetes. Also disclosed are processes for the preparation of such compounds; pharmaceutical compositions comprising such compounds; and methods of treatment comprising administering such compounds and compositions when indicated for, inter alia, long term, prophylactic treatment of the diabetes syndrome.
- -
-
-
- Ytterbium Metal-promoted Novel Cross-coupling Reaction between Diaryl Ketones and Electrophiles
-
In the presence of Yb metal, diaryl ketones react nucleophilically with octan-2-one, acetonitrile, epoxides, and CO2 to give the corresponding unsymmetrical pinacols, α-hydroxy ketones, 1,3-diols, and α-hydroxy carboxylic acids, respectively.
- Hou, Zhaomin,Takamine, Kan,Aoki, Osamu,Shiraishi, Hiroyuki,Fujiwara, Yuzo,Taniguchi, Hiroshi
-
p. 668 - 670
(2007/10/02)
-
- Nucleophilic Addition of Lanthanoid Metal Umpoled Diaryl Ketones to Electrophiles
-
Ytterbium metal promoted cross-coupling reactions of diaryl ketones with a variety of electrophiles are described.Diaryl ketones treated with 1-2 equiv of Yb metal react smoothly with other ketones, nitriles, epoxides, CO2, etc., to give the corresponding unsymmetrical pinacols, α-hydroxy ketones, 1,3-diols, α-hydroxy carboxylic acids, etc., in good yields respectively.These reactions occur via nucleophilic addition of the intermediates 4a-c to electrophiles.Reaction of benzophenone (1a) with Yb metal is discussed in detail and some information on the composition of the intermediates of the reaction of diaryl ketones with Yb metal are also given.
- Hou, Zhaomin,Takamine, Kan,Aoki, Osamu,Shiraishi, Hiroyuki,Fujiwara, Yuzo,Taniguchi, Hiroshi
-
p. 6077 - 6084
(2007/10/02)
-
- Ophthalmic wound healing with aldose reductase inhibitors
-
Method of promoting healing of ocular wounds comprising the topical application of an aldose reductase inhibitor; compositions comprising such inhibitors are also disclosed.
- -
-
-
- The E1cb Route for Ester Hydrolysis; Volumes of Activation as an Additional Criterion of Mechanism
-
Hydrolyses of esters which possess an acidic proton at the α or vinylogous position can, in principle, hydrolyse by the E1cb route via a ketenoid intermediate.To the kinetic evidence for such a mechanism in the hydrolyses of 4-hydroxybenzoates, malonates, acetoacetates and fluorenecarboxylates is now added the further criterion of volumes of activation.Values of ΔV(excit.) for reactions proceeding by the E1cb route are positive and contrast with the negative values associated with hydrolyses by the more usual BAc2 mechanism.
- Isaacs, Neil S.,Najem, Tariq S.
-
p. 557 - 562
(2007/10/02)
-
- Process for the preparation of fluorene-9-carboxylic acid
-
An improved process for the preparation of fluorene-9-carboxylic acid comprising reacting fluorene and a dialkyl carbonate with alkyls of 1 to 5 carbon atoms in the presence of a member of the group consisting of alkali metal hydrides or potassium alcoholate of an aliphatic alcohol of 1 to 5 carbon atoms, neutralizing the mixture and saponifying the resulting fluorene-9-carboxylic acid ester to obtain fluorene-9-carboxylic acid in good yields.
- -
-
-
- Spiro-tricyclicaromatic succinimide derivatives as inhibitors of aldose reductase
-
Disclosed are substituted or unsubstituted planar tricyclic fluorene or nuclear analogs thereof, spiro-coupled to a five-membered ring containing a secondary amide, and the pharmaceutically acceptable salts thereof. These compounds are useful, inter alia, in the treatment of diabetes. Also disclosed are processes for the preparation of such compounds; pharmaceutical compositions comprising such compounds; and methods of treatment comprising administering such compounds and compositions when indicated for, inter alia, long term, prophylactic treatment of the diabetes syndrome.
- -
-
-
- EFFECT OF AN AROMATIC ESTER CONJUGATE BASE ON E1cB ESTER HYDROLYSIS. ALKALINE HYDROLYSIS OF FLUORENE-9-CARBOXYLATE ESTERS
-
A series of alkyl and substituted-aryl esters of fluorene-9-carboxylic acid have been synthesised and their alkaline hydrolyses studied.The pH profiles for hydrolysis indicated substrate ionisation at higher pH values (confirmed by spectral studies) and kinetic pK values for a number of these esters were obtained at 25 deg C.At high pH (pKa) the rate of hydrolysis became independent of pH with the observed rate constant in this high pH plateau region being called k'.A plot of logarithm (to base 10) of k' versus pKa of the conjugate acid of the appropriate leaving group consisted of two limbs, A and B, flanking a minimum.The slopes of the plots described above for regions A and B were -1.01+/-0.05 and +0.11+/-0.01 respectively.Region A, of high negative slope, was shown to correspond to an E1cB reaction of the title esters on the basis of linear free energy relationship arguments, the solvent deuterium kinetic isotope effect, activation parameters, and comparison with the 9-methyl-blocked analogues, as well as by the observation of saturation kinetics in aniline buffers at low pH.Region B was shown to correspond to a rate-determining step of attack of hydroxide ion on the limiting amount of ester in its neutral form.The low eliminative reactivity of fluorene ester anions was discussed along with factors considered in the literature for explaining elimination rates of ester anions.
- Alborz, Manoochehr,Douglas, Kenneth T.
-
p. 331 - 340
(2007/10/02)
-
- Treating cardiac arrhythmias
-
Fluorenes bearing a 9-aminoalkyl substituent are useful antiarrhythmic agents. Pharmaceutical formulations containing such compounds are provided, as well as a method of treatment.
- -
-
-
- Decarboxylation process
-
Decarboxylation of carboxylic acids using diazabicycloalkenes and, if desired, also a simple copper salt, as the means for decarboxylation.
- -
-
-
