Bipyridinium Chlorochromate Research Articles

M-Chloroperbenzoic acid-oxchromium (VI)-mediated cleavage of 2,4,5-trisubstituted oxazoles

An array of 2-substituted-4,5-diphenyloxazoles were found to be cleaved to triacylamines and diacylamines (imides) using a reagent system composed of m-chloroperbenzoic acid (MCPBA) and 2,2′-bipyridinium chlorochromate (BPCC). The 2-alkyl-4,5-diphenyloxazoles give imides (38–60%) as the predominant cleavage product while the 2-aryl-4,5-diphenyloxazoles give triacylamines (44–71%). Two mechanisms involving intermediates such as cyclic endoperoxides or oxachromacycles were proposed. An application of the oxidative cleavage to the multi-step synthesis of (±)-phoracantholide I seco acid is detailed.

Oxidation of Cinnnamic Acid by Bipyridinium Chlorochromate – Rate Determination at Various Temperatures

The kinetics of oxidation of cinnamic acid by BPCC in aqueous acetic acid (50%-50% v/v) in the presence of sulphuric acid has been studied. In order to arrive at a correlation between the synthetic efficacy and structure of reagent, the kinetics of oxidation of cinnamic acid with BPCC has been carried out in aqueous acetic acid. The reaction exhibit first order dependence on both the oxidant and substrate concentrations. In this part we have studied oxidation of cinnnamic acid by bipyridiniumchlorochromate and determined rate of the reaction at various temperature

크롬(VI)-헤테로고리 착물(2,4'-비피리디늄 클로로크로메이트)에 의한 치환 벤질 알코올류의 산화반응에서 속도론과 메카니즘

Cr(VI)-heterocyclic complex (2,4’-bipyridinium chlorochromate) was synthesized by the reaction between heterocyclic compound(2,4’-bipyridine) and chromium trioxide, and characterized by IR and ICP analysis. The oxidation of benzyl alcohol using 2,4’-bipyridinium chlorochromate in various solvents showed that the reactivity increased with the increase of the dielectric constant (e), in the order : N,N-dimet-hylformamide (DMF) > acetone > chloroform > cyclohexene. In the presence of DMF solvent with acidic catalyst such as hydrochloric acid (HCl solution), 2,4’-bipyridinium chlorochromate oxidized benzyl alcohol (H) and its derivatives (p-CH3, m-Br, m-NO2). Electron-donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. The Hammett reaction constant (ρ) was -0.67 (303 K). The observed experimental data have been rationalize the proton transfer occurred followed the formation of a chromate ester in the rate-determining step.

2,2'-Bipyridinium Chlorochromate에 의한 치환 벤질 알코올류의 산화반응과 메카니즘에 관한 연구

2,2`-Bipyridinium chlorochromate[] was synthesized by the reaction of 2,2`- bipyridine with chromium(VI) trioxide in 6M HCl. The structure was characterized by IR and ICP analysis. The oxidation of benzyl alcohol using 2,2`-bipyridinium chlorochromate in various solvents showed that the reactivity increased with the increase in the order of the dielectric constant(), in the order: cyclohexene, H, m-Br, ) in N,N`-dimethylformamide. Electron-donating substituents accelerated the reaction, whereas electron acceptor groups retarded the reaction. The Hammett reaction constant() was -0.64(303K). The oxidation reactivity of alcohols can be a useful factor to study about physical properties such as thermal stability, when the polysilsesquioxane solution is ready for an applying coating agent. The observed experimental data was used to rationalized the hydride ion transfer in the rate-determining step.

A direct arylation-oxidation route to 3-arylisoindolinone inhibitors of MDM2-p53 interaction

A route to the MDM2-p53 inhibitor isoindolinone pharmacophore from a pre-formed phthalimide is detailed. The route involves treatment of 3-hydroxy-2-(n-propyl)isoindolinone with a substituted benzene in the presence of triflic acid. The resulting 3-aryl-2-(n-propyl)isoindolinones are then oxidized to the corresponding 3-hydroxy-3-aryl-2-(n-propyl) isoindolinones by treatment with 2,2’-bipyridinium chlorochromate. The benzylic oxidation represents a rather rare oxochromium (VI)-mediated reaction in which a selective C–H to C–OH transformation occurs.

ChemInform Abstract: 2,2′-Bipyridinium Chlorochromate/m-Chloroperbenzoic Acid-Mediated Cleavage of Cyclic Acetals to Hydroxyesters.

Abstract Benzylidene acetals are cleaved to hydroxyesters by means of a reagent system composed of 2,2′-bipyridinium chlorochromate (BPCC) and m -chloroperbenzoic acid. Oxidative cleavage of a 4,6-O-benzylidene glucose derivative affords a 6-O-benzoyl derivative.

Correlation analysis of reactivity in the oxidation of substituted benzyl alcohols by 2,2' -bipyridinium chlorochromate

Oxidation of benzyl alcohol and some ortho-, meta- and para-monosubstituted ones by 2,2'-bipyridinium chlorochromate (BPCC) in DMSO leads to the formation of corresponding benzaldehydes. The reaction is first order in both BPCC and the alcohol. The reaction is promoted by hydrogen ions; the hydrogen-ion dependence has the form : k obs = a + b [H + ]. Oxidation of α,α-dideuteriobenzyl alcohol (PhCD 2 OH) has exhibited a substantial primary kinetic isotope effect (k H /k D = 5.60 at 298 K). The reaction has been studied in nineteen organic solvents and the effect of solvent analysed using Taft's and Swain's multi-parametric equations. The rates of oxidation of para- and meta-substituted benzyl alcohols have been correlated in terms of Charton's triparametric LDR equation whereas the oxidation of ortho-substituted benzyl alcohols with tetraparametric LDRS equation. The oxidation of para-substituted benzyl alcohols is more susceptible to the delocalization effect than that of ortho- and meta-substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed.

Structure-reactivity correlation in the oxidation of substituted benzaldehydes by 2,2' -bipyridinium chlorochromate

Oxidation of thirty six monosubstituted benzaldehydes by 2,2'-bipyridinium chlorochromate (BPCC) in dimethylsulphoxide (DMSO), leads to the formation of corresponding benzoic acids. The reaction is of first order with respect to both BPCC and aldehydes. The reaction is promoted by hydrogen ions; the hydrogen ion dependence has the form k obs = a + b[H + ]. The oxidation of [ 2 H]benzaldehyde (PhCDO) exhibited a substantial primary kinetic isotope effect. The reaction was studied in nineteen different organic solvents and the effect of solvent was analysed using Taft's and Swain's multi-parametric equations. The rates of the oxidation of para- and meta-substituted benzaldehydes showed excellent correlation in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes were correlated well with tetraparametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalized effect than is the oxidation of ortho- and meta-substituted compounds, which display a greater dependence on the field effect. The positive value of n suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed.

Kinetics and mechanism of the oxidation of organic sulphides by 2,2′-bipyridinium chlorochromate

The oxidation of 34 organic sulphides hy 2,2′-hipyridinium chlorochromate (BPCC) resulted in the formation of the corresponding sulphoxides. The reaction is first order with respect to both BPCC and the sulphide, and is catalysed by hydrogen ions. The hydrogen-ion dependence has the form:k obs = a+b[H+]. The oxidation was studied in 19 different organic solvents. An analysis of the solvent effect by Swain’s equation showed that the both cation-and anion-solvating powers of the solvents play important roles. The rates of oxidation meta- andp-substituted phenyl methyl sulphides were correlated with Charton’s LDR equation. The rates of theo-compounds showed excellent correlation with the LDRS equation. Oxidation of thep-compounds is more susceptible to the delocalizationeffect. Oxidation of themcompounds exhibited a greater dependence on the field effect. In the oxidation of theo-compounds, the contribution of delocalized effect is slightly more than that of the field effect. The oxidation of alkyl phenyl sulphides is subject to both polar and steric effects of the alkyl groups. Polar reaction constants are negative, indicating an electron-deficient sulphur centre in the rate-determining step. A mechanism involving formation of a sulphurane intermediate in the slow step has been proposed.

Kinetics and mechanism of the oxidation of some α‐hydroxy acids by 2,2′‐bipyridinium chlorochromate

AbstractThe oxidation of glycolic, lactic, malic, and a few substituted mandelic acids by 2,2′‐bipyridinium chlorochromate (BPCC) in dimethylsulphoxide leads to the formation of corresponding oxoacids. The reaction is first order each in BPCC and the hydroxy acids. The reaction is catalyzed by the hydrogen ions. The hydrogen ion dependence has the form: kobs = a + b [H+]. The oxidation of α‐deuteriomandelic acid exhibited a substantial primary kinetic isotope effect (kH/kd = 5.29 at 303 K). Oxidation of p‐methylmandelic acid was studied in 19 different organic solvents. The solvent effect has been analyzed by using Kamlet's and Swain's multiparametric equations. A mechanism involving a hydride ion transfer via a chromate ester is proposed. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 248–254, 2002

A facile scheme for phthalimide ⇌ phthalimidine conversion

Desulfurization of phenylthiolactams using an ultrasound-promoted Raney nickel protocol yields the corresponding N-substituted phthalimidines. Benzylic oxidation of the N-substituted phthalimidines by treatment with 2, 2′-bipyridinium chlorochromate m- chloroperbenzoic acid (BPCC/MCPBA) affords the original phthalimides. Thereduction-desulfurization is applied to the preparation of a deoxythalidomide derivative which is a TNF-α inhibitor.

Kinetics and Mechanism of the Oxidation of Oxalic and Formic Acids by 2,2′-Bipyridinium Chlorochromate

The oxidation of formic and oxalic acids by 2,2′-bipyridinium chlorochromate (BPCC) involves initial formation of an anhydride intermediate and its subsequent decomposition via a symmetrical cyclic transition state.

ChemInform Abstract: Kinetics and Mechanism of the Oxidation of Diols by 2,2′‐Bipyridinium Chlorochromate.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

2,2′-Bipyridinium chlorochromate/ m-chloroperbenzoic acid-mediated cleavage of cyclic acetals to hydroxyesters

Benzylidene acetals are cleaved to hydroxyesters by means of a reagent system composed of 2,2′-bipyridinium chlorochromate (BPCC) and m-chloroperbenzoic acid. Oxidative cleavage of a 4,6-O-benzylidene glucose derivative affords a 6-O-benzoyl derivative.

Kinetics and Mechanism of the Oxidation of Diols by 2,2′-Bipyridinium Chlorochromate

The oxidation of diols by 2,2′-bipyridinium chlorochromate involves a hydride-ion transfer via a chromate ester intermediate.

Oxidative rearrangement of sulfur-containing tertiary allylic alcohols: synthesis of 2-cycloalkenones bearing 3-[(phenylthio)methyl] and 3-[2-alkyl-1,3-dithian-2-yl] substituents

Substrate 1-[(phenylthio)methyl]-2-cycloalkenols 3a-d and 1-[2-alkyl-1,3-dithian-2-yl]cyclohexenols 1a-a were prepared by adding [(phenylthio)methyl]lithium and 2-lithio-2-alkyl-1,3-dithianes, respectively, in the 1,2-mode to various 2-cycloalkenones. The ranges of yields for the additions were 86-96% in the (phenylthio)methyl series and 69-88% in the dithiane series. A representative compound from each range of substrate tertiary allylic alcohols was then treated with a series of oxochromium(VI)-amine reagents such as pyridinium chlorochromate (PCC), pyridinium dichromate (PDC), the Collins reagent (CrO 3 .Pyr 2 ), and 2,2'-bipyridinium chlorochromate (BPCC)