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A Unified Strategy for the Asymmetric Synthesis of Highly Substituted 1,2-Amino Alcohols Leading to Highly Substituted Bisoxazoline Ligands
A general procedure for the asymmetric synthesis of highly substituted 1,2-amino alcohols in high yield and diastereoselectivity is described that uses organometallic additions of a wide range of nucleophiles to tert-butylsulfinimines as the key step. The addition of organolithium reagents to these imines follows a modified Davis model. The diastereoselectivity for this reaction depends significantly on both the nucleophile and electrophile. These highly substituted 1,2-amino alcohols are used to synthesize stereochemically diverse and structurally novel, polysubstituted 2,2′-methylene(bisoxazoline) ligands in high yields.
Shrestha, Bijay,Rose, Brennan T.,Olen, Casey L.,Roth, Aaron,Kwong, Adon C.,Wang, Yang,Denmark, Scott E.
supporting information
p. 3490 - 3534
(2021/02/16)

1,5,7-Triazabicyclo[4.4.0]dec-5-ene Enhances Activity of Peroxide Intermediates in Phosphine-Free α-Hydroxylation of Ketones
The critical role of double hydrogen bonds was addressed for the aerobic α-hydroxylation of ketones catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), in the absence of either a metal catalyst or phosphine reductant. Experimental and theoretical investigations were performed to study the mechanism. In addition to initiating the reaction by proton abstraction, a more important role of TBD was revealed, that is, to enhance the oxidizing ability of peroxide intermediates, allowing DMSO to be used rather than commonly used phosphine reductants. Further characterizations with nuclear Overhauser effect spectroscopy (NOESY) confirmed the presence of double hydrogen bonds between TBD and the ketone, and kinetic studies suggested the attack of dioxygen on the TBD-enol adduct to be the rate-determining step. This work should encourage the application of TBD as a catalyst for oxidations.
Wang, Yongtao,Lu, Rui,Yao, Jia,Li, Haoran
supporting information
p. 6631 - 6638
(2021/02/05)

Time-Economical Synthesis of Diarylacetates Enabled by TfOH-Catalyzed Arylation of α-Aryl-α-Diazoesters with Arenes
Diarylacetates are privileged structures of many bioactive natural products and pharmaceutical compounds. A time-economical synthesis of diarylacetates by TfOH-catalyzed arylation of α-aryl-α-diazoesters with arenes is described. This protocol provides a variety of diarylacetates in good yields with broad substrate scope, excellent functional group compatibility, and mild reaction conditions. Also, a new mechanism for the arylation reaction of α-aryl-α-diazoesters with arenes under TfOH catalysis is presented.
Hu, Sha,Wu, Jiale,Lu, Zuolin,Wang, Jiaqi,Tao, Yuan,Jiang, Meifen,Chen, Fener
p. 2559 - 2563
(2021/04/09)

Room Temperature Coupling of Aryldiazoacetates with Boronic Acids Enhanced by Blue Light Irradiation
A visible-light-promoted photochemical protocol is reported for the coupling of aryldiazoacetates with boronic acids. This photochemical reaction shows great enhancement compared to the same protocol performed in the absence of light. Except for a few cases, the room temperature coupling in the dark (thermal process) generally does not work. When it does, it is likely to also involve free carbenes as key intermediates. Alternatively, photochemical reactions show a broad scope, can be performed under air and tolerate a wide variety of functional groups. Reaction-evolution monitoring, DFT calculations and control experiments have been used to evaluate the main aspects of this intricate mechanistic scenario. Biologically active molecules Adiphenine, Benactyzine and Aprophen have been prepared as examples of synthetic applications.
da Silva, Amanda F.,Afonso, Marco A. S.,Cormanich, Rodrigo A.,Jurberg, Igor D.
p. 5648 - 5653
(2020/04/22)

A 2 the hydroxy [...] ― 2,2 the the ― 3 α [...] diphenylgermanium acetic acid [...] (8 the [...] azabicyclo [3, 2, 1]) ― 3 the method for the preparation of octyl [...]
The invention discloses a method for preparing 2-hydroxy-2,2-diphenylacetic acid-3alpha-(8-aza-bicyclo(3,2,1))-3-trioctyl. The method comprises the following steps of: by taking dibenzoyl as a raw material, carrying out rearrangement on the raw material so as to obtain dihydroxy-phenylacetic acid; reacting dihydroxy-phenylacetic acid with dimethyl carbonate under the DBU catalysis and microwave actions so as to obtain methyl benzilate; reacting the methyl benzilate with tropine so as to obtain tropine benzilate; and carrying out N formylation and alcoholysis on the obtained tropine benzilate so as to obtain nor-tropine benzilate. Compared with the prior art, the total reaction time of the method disclosed by the invention is greatly reduced, the total yield is increased greatly, and the reaction condition is more simple, and therefore, the method is suitable for industrial production.
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(2016/12/12)

One-pot esterification and amide formation via acid-catalyzed dehydration and ritter reactions
Esterification of carboxylic acid is achieved using acetonitrile as a water trap. Water liberated during esterification is consumed in cyanide hydrolysis, thereby driving the esterification to completion. Substrates having carboxylic acid and nitrile groups undergo intramolecular dehydration and rehydration to amido esters in the absence of acetonitrile. Cyano acids also undergo esterification and Ritter reaction in one pot when excess alcohol is used. For the first time, we have observed an interesting Ritter reaction of primary alcohols, leading to ester amide product in one pot. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
Dawar, Pankaj,Raju, M. Bagavan,Ramakrishna, Ramesha Andagar
supporting information
p. 836 - 846
(2014/03/21)

Highly efficient C-H hydroxylation of carbonyl compounds with oxygen under mild conditions
A transition-metal-free Cs2CO3-catalyzed α-hydroxylation of carbonyl compounds with O2 as the oxygen source is described. This reaction provides an efficient approach to tertiary α-hydroxycarbonyl compounds, which are highly valued chemicals and widely used in the chemical and pharmaceutical industry. The simple conditions and the use of molecular oxygen as both the oxidant and the oxygen source make this protocol very environmentally friendly and practical. This transformation is highly efficient and highly selective for tertiary C(sp3)-H bond cleavage. OH, so simple! A transition-metal-free Cs2CO 3-catalyzed α-hydroxylation of carbonyl compounds with O 2 provided a variety of tertiary α-hydroxycarbonyl compounds (see scheme; DMSO=dimethyl sulfoxide), which are widely used in the chemical and pharmaceutical industry. The simple conditions and the use of molecular oxygen as both the oxidant and the oxygen source make this protocol very efficient and practical.
Liang, Yu-Feng,Jiao, Ning
supporting information
p. 548 - 552
(2014/01/23)

One-pot esterification and Ritter reaction: Chemo- and regioselectivity from tert-butyl methyl ether
tert-Butyl methyl ether (TBME) has been effectively used as a reagent for esterification of carboxylic acids. By varying amounts of sulfuric acid, a remarkable regioselectivity in esterification has been demonstrated. Additionally, under the present reaction conditions, one-pot esterification and Ritter reaction are achieved in almost quantitative yield.
Dawar, Pankaj,Bhagavan Raju,Ramakrishna, Ramesha A.
supporting information; experimental part
p. 4262 - 4265
(2011/08/21)

A dinuclear palladium catalyst for α-Hydroxylation of carbonyls with O2
A chemo- and regioselective α-hydroxylation reaction of carbonyl compounds with molecular oxygen as oxidant is reported. The hydroxylation reaction is catalyzed by a dinuclear Pd(II) complex, which functions as an oxygen transfer catalyst, reminiscent of an oxygenase. The development of this oxidation reaction was inspired by discovery and mechanism evaluation of previously unknown Pd(III)-Pd(III) complexes.
Chuang, Gary Jing,Wang, Weike,Lee, Eunsung,Ritter, Tobias
supporting information; experimental part
p. 1760 - 1762
(2011/04/15)

Electroreductive acylation of aromatic ketones with acylimidazoles
The intermolecular reductive coupling of aromatic ketones with acylimidazoles was effected by electroreduction in the presence of chlorotrimethylsilane and gave α-trimethylsiloxy ketones and esters. The best result was obtained using Bu4NPF6 as a supporting electrolyte and a Pb cathode in THF. The α-trimethylsiloxy-containing products were transformed to the corresponding α-hydroxy ketones and esters by treatment with TBAF in THF. This method was also effective for the intramolecular reductive coupling of δ- and ε-keto acylimidazoles.
Kise, Naoki,Agui, Syun,Morimoto, Shinji,Ueda, Nasuo
p. 9407 - 9410
(2007/10/03)

MEDICAMENTS FOR INHALATION COMPRISING ANTICHOLINERGICS AND A BETAMIMETIC
The present invention relates to novel pharmaceutical compositions comprising one or more, preferably one anticholinergic 1 and a betamimetic of formula 2 processes for preparing them and their use in the treatment of respiratory complaints.
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Page/Page column 43; 44

(2008/06/13)

Medicaments for inhalation comprising an anticholinergic and a betamimetic
A pharmaceutical composition comprising an anticholinergic and a betamimetic of formula 2 optionally together with a pharmaceutically acceptable excipient, the anticholinergic and the betamimetic optionally in the form of their enantiomers, mixtures of their enantiomers, their racemates, their solvates, or their hydrates, processes for preparing them, and their use in the treatment of asthma, COPD, or other inflammatory or obstructive respiratory complaints.
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(2008/06/13)

Rhodium-catalyzed addition of arylstannanes to carbon-heteroatom double bond
The addition of arylstannanes to the carbon-heteroatom double bond in the presence of a catalytic amount of a cationic rhodium complex ([Rh(cod)(MeCN)2]BF4) was examined. The reactions of aldehydes, α-dicarbonyl compounds, and N-substituted aldimines with the arylstannanes gave corresponding alcohols, α-hydroxy carbonyl compounds, and amines, respectively. An arylrhodium complex generated by the transmetalation with the arylstannane was probably the active catalytic species.
Oi, Shuichi,Moro, Mitsutoshi,Fukuhara, Hiroe,Kawanishi, Takanori,Inoue, Yoshio
p. 4351 - 4361
(2007/10/03)

Anticholinergics, processes for the preparation thereof, and pharmaceutical compositions
A compound of formula 1 wherein: X? is an anion with a single negative charge; A and B, which are identical or different, are each —O—, —S—, —NH—, —CH2—, —CH═CH—, or —N(C1-C4-alkyl)-; R is hydrogen, hydroxy, —C1-C4-alkyl, —C1-C4-alkyloxy, —C1-C4-alkylene-halogen, —O—C1-C4-alkylene-halogen, —C1-C4-alkylene-OH, —CF3, —CHF2, —C1-C4-alkylene-C1-C4-alkyloxy, —O—COC1-C4-alkyl, —O—COC1-C4-alkylene-halogen, —C1-C4-alkylene-C3-C6-cycloalkyl, —O—COCF3, or halogen; R1 and R2, which are identical or different, are each —C1-C5-alkyl, which is optionally substituted by —C3-C6-cycloalkyl, hydroxy, or halogen, or R1 and R2 together are a —C3-C5-alkylene bridge; R3, R4, R3′, and R4′, which are identical or different, are each hydrogen, C1-C4-alkyl, C1-C4-alkyloxy, hydroxy, —CF3, —CHF2, —CN, —NO2, or halogen; Rx and Rx′, which are identical or different, are each hydrogen, C1-C4-alkyl, C1-C4-alkyloxy, hydroxy, —CF3, —CHF2, —CN, —NO2, or halogen, or Rx and Rx′ together are a single bond or a bridging group selected from —O—, —S—, —NH—, —CH2—, —CH2—CH2—, —N(C1-C4-alkyl)-, —CH(C1-C4-alkyl)-, and —C(C1-C4-alkyl)2-, or a pharmacologically acceptable acid addition salt thereof, processes for preparing, them and their use in pharmaceutical compositions.
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Page 6

(2010/01/31)

Alkylating polymers: Resin-released carbenium ions as versatile reactive intermediates in polymer-assisted solution-phase synthesis
Solid-supported diazoalkane analogues for the smooth and clean esterifications of carboxylic acids [Eq. (1)] as well as of complex compound mixtures: the alkylating polymers presented here were synthesized as solid-supported 3-alkyl-l-aryltriazenes and ar
Rademann, Jorg,Smerdka, Joachim,Jung, Gnther,Grosche, Philipp,Schmid, Dietmar
p. 381 - 385
(2007/10/03)

Oxidation of Methyl Trimethylsilyl Ketene Acetals to α-Hydroxyesters with Urea Hydrogen Peroxide Catalyzed by Methyltrioxorhenium
In the presence of catalytic amounts of MTO, methyltrioxorhenium, methyl trimethylsilyl ketene acetals are oxidized with urea hydrogen peroxide to afford α-hydroxy and α-siloxy esters. On treatment with potassium fluoride, the α-hydroxy esters are obtained in high yields.
Stankovic, Sasa,Espenson, James H.
p. 5528 - 5530
(2007/10/03)

Biomimetic oxidation of denaverine hydrochloride
The behavior of denaverine (1) in various chemical model systems based on metalloporphyrins as catalysts was investigated to determine the possible oxidative metabolism. The resulting derivatives were compared to a biological model system and in vivo metabolism in rat and human.
Smolinka, Kai,G?ber, Berthold
p. 679 - 683
(2007/10/03)

Synthesis, antimuscarinic activity and quantitative structure-activity relationship (QSAR) of tropinyl and piperidinyl esters
A series of tropinyl and piperidinyl esters was synthesized and evaluated for inhibitory activities on the endothelial muscarinic receptors of rat (M3) and rabbit (M2) aorta. Some of the esters (cyclohexylphenylglycolates and cyclohexylphenylpropionates) were found to be better antimuscarinic compounds than standard M2 and M3 inhibitors such as AFDX116 and 4-diphenylacetoxy-N-methylpiperidine (DAMP), with pKEC50 values in the range of 8-9. A few esters were found to be more selective M3 than M2 inhibitors, but these tended to have low activities. The hydrophobic, electronic and steric characteristics of these esters were correlated with antimuscarinic activity by using appropriate parameters representing hydrophobicity (HPLC capacity factor, log k(w), size (molecular volume) and electronic character (Taft's polar substituent constant δ and 13C chemical shift difference Δδ). Finally, 92% of the M2-inhibitory activities of the esters could be accounted for by the size and electronic character σ* of the side chain. In contrast, the M3-inhibitory activities of these esters were mainly attributed to the electronic nature (σ*, Δδ) of the side chain, with good activity being associated with electron-withdrawing groups. Visualization of the comparative molecular field analysis (CoMFA) steric and electrostatic fields provided further confirmation of the structure-activity relationship (SAR) derived from traditional quantitative structure-activity relationship (QSAR) approaches.
Xu, Rong,Sim, Meng-Kwoon,Go, Mei-Lin
p. 231 - 241
(2007/10/03)

Hydroxylation of carbanions with lithium teri-butyl peroxide acting as an oxenoid
The lithium salt of terf-butyl hydroperoxide can convert alkyl, vinyl, aryl carbanions, acetylides and various enolates into the corresponding hydroxylated derivatives in good yields and under mild conditions. Eisevier.
Julia, Marc
p. 15 - 24
(2007/10/03)

Dynamics of reaction of [meso-tetrakis(2,6-dimethyl-3-sulfonatophenyl)porphinato]-iron(III) hydrate with various alkyl hydroperoxides in aqueous solution. 4. Comparison of kinetic parameters and D2O solvent isotope effects
The second-order rate constants (kly) for the reactions of the alkyl hydroperoxides (Ph)2(MeOCO)COOH and (Ph)(Me)2COOH with [meso-tetrakis(2,6-dimethyl-3-sulfonatophenyl)porphinato]iron(III) hydrate [(1)FeIII(X)2 (X = H2O or OH-)] have been determined in water over the pH range 1-13 by using the one-electron oxidizable trapping agent 2,2′-azinobis(3-ethylbenzthiazolinesulfonate) (ABTS). The complex pH dependencies of kly reflect the pH dependency of the structure of reactants and intermediates as shown in Scheme II. Plots of log kly vs pH were fitted by a steady-state kinetic expression (eq 1) shown previously to describe the pH dependence of the reaction of (CH3)3COOH with (1)FeIII(X)2. The dependencies of the rate constants for O-O bond cleavage (K2 and k4, Scheme II) of the ligated hydroperoxides YOOH to the pKa of the leaving group YOH (δ(log k2)/δpκaYOH and (δ(log k4)/δpκaYOH can be isolated from the pH dependencies of the kly values and are determined to be -0.22 and -0.13, respectively. Thus, the sensitivity of rate constants for the cleavage of the O-O bond of ligated hydroperoxide to its polarity is small. Kinetic deuterium solvent isotope effects for reaction of (Ph)2(MeOCO)COOH with (1)FeIIIX2 have been found to be in accord with those determined previously for (CH3)3COOH.
Gopinath, Enona,Bruice, Thomas C.
p. 6090 - 6094
(2007/10/02)

The dynamics of the reactions of methyl diphenylhydroperoxyacetate with [meso-tetrakis(2,6-dimethyl-3-sulfonatophenyl)porphinato]-manganese(III) hydrate and [meso-tetrakis(2,6-dichloro-3-sulfonatophenyl)porphinato]-manganese(III) hydrate and imidazole complexes. Comparison of the reactions of manganese(III) and iron(III) porphyrins
The reactions of (Ph)2(MeOCO)COOH with two water-soluble non-μ-oxo dimer-forming manganese(III) porphyrins, [meso-tetrakis(2,6-dimethyl-3-sulfonatophenyl)porphinato]manganese(III) hydrate, [(1)MnIII(X)2], and [meso-tetrakis(2,6-dichloro-3-sulfonatophenyl)porphinato]manganese(III) hydrate [(2)MnIII(X)2, where X = HO- or H2O], have been examined in aqueous solution [30 °C; μ = 0.2 (with NaNO3); pH 5.3-12.6] and compared to the reaction with the iron porphyrin (1)FeIII(X)2. Kinetic studies were carried out in the presence and absence of imidazole, with the sodium salt of 2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) as a trap for higher valent manganese porphyrin intermediates. Reactions were found to be first-order in both [(porph)MnIIIX)2]i and [(Ph)2(MeOCO)COOH], and independent of [ABTS]i and buffer concentrations [H2PO4-/HPO42- (pH 7.3), HCO3-/CO32- (pH 9.8), and 2,4,6-trimethylpyridine-H+/2,4,6-trimethylpyridine (pH 8.4 and 7.5)]. Thus, the reactions are not subject to general base or general acid catalysis. A plot of the log of the pH-dependent second-order rate constant (kly) vs pH may be fit by an equation (eq 8) derived by assumption of steady state in the reactive species (porph)MnIII(OH)((Ph)2(MeOCO)COOH)/(porph)Mn III(H2O)((Ph)2(MeOCO)COO) and [(porph)MnIII(OH)((Ph)2- (MeOCO)COO)]-. Product analysis in the absence of ABTS provided 9% yield of (Ph)2CO and 81% yield of (Ph)2(MeO-CO)COH. In the presence of the ABTS trap (Ph)2CO is formed in 12% yield, and the main product is again (Ph)2(MeOCO)COH (55%). In reactions with (1)MnIII(X)2 and (2)MnIII(X)2 (pH 5.3-12.6) a high spin, d3, manganese(IV) intermediate (μ = 3.90 μBat 295 K) was observed. A comparison of the log kly vs pH profiles for the reaction of (1)MnIII(X)2 and (1)FeIII(X)2 with (Ph)2(MeOCO)COOH showed that kly values are comparable at high pH while at lower pH, (1)FeIII(X)2 is far more reactive. This difference in log kly vs pH profiles for (1)MnIII(X)2 vs (1)FeIII(X)2 finds explanation in the differing pH dependence of potentials for Ie- reduction of Mn(IV) and Fe(IV) species. Addition of imidazole resulted in an enhancement in the rate of reaction. Apparent equilibrium constants were determined at various values of pH for monoligation of imidazole, and the dependence of rate on pH was employed to show that the reactive intermediates are (i) low pH, [(1)MnIII(ImH)((Ph)2- (MeOCO)COOH)]+; (ii) intermediate pH, (1)MnIII(Im)((Ph)2(MeOCO)COOH)/(1)Mn III(ImH)((Ph)2(MeOCO)COO); and (iii) high pH, [(1)MnIII(Im)((Ph)2(MeOCO)COO)]-. Imidazole ligation provided at most a rate enhancement of ~100-fold.
Arasasingham, Ramesh D.,Bruice, Thomas C.
p. 6095 - 6103
(2007/10/02)

Nucleophilic substitution in diphenylmethyl derivatives. II. Methanolysis of α substituents of diphenylacetic acid and its derivatives
The nucleophilic displacement of α substituents of diphenylacetic acid and its methyl ester by MeOH under a variety of experimental conditions allowed us to establish that the reaction occurs rapidly in one of the following structural combinations: (a) carboxylate anion and a good leaving group; (b) carboxylic group and a less reactive leaving group; (c) methyl ester and a proton-activated, poor leaving group.The importance of internal hydrogen bonding (case b) was the governing factor in the outcome of the reaction of hydroxydiphenylacetic acid (3a) and its methyl ester 3b with acetyl chloride.The key intermediate in substitution at the α carbon is thought to be a carbocation stabilized both by the attached phenyl groups and, to a smaller extent, by the carboxyl group.
Strazzolini, Paolo,Poiana, Marco,Verardo, Giancarlo,Giumanini, Angelo G.
p. 283 - 289
(2007/10/02)

Electrochemical Hydroxylation, Methoxylation, and Hydroxymethylation of Active Methine Compounds
Hydroxylation, methoxylation, or hydroxymethylation at the active methine group of phenylmalonate, benzylmalonate and diphenylacetate were achieved by anodic oxidation.
Kawabata, Jin-ichi,Nozawa, Koohei,Kawai, Ken-ichi,Nakajima, Shoichi
p. 181 - 183
(2007/10/02)

Reduction of Long Chain and Bulky Carboxylic Esters by Sodium Tetrahydroborate
Methyl esters of long chain fatty acids as well as esters with functional (OH) and/or bulky substituents in alpha position and in the OR moiety may be effectively reduced with an excess of sodium tetrahydroborate at moderate temperature in dioxane-water without catalysts.The reaction has been applied to the reduction of a pool of triglycerides of natural origin (virgin olive oil) in order to obtain a mixture of the acyl residues reduced to the corresponding alcohols without any structural or configurational modification.They, no matter which was the advancement of the reaction, seemed to reproduce quite well the overall acyl composition, as shown by GC-MS analysis: the feasibility of such quantitative analysis may be extended, in order to obtain confirmatory evidences on the component identifications and to perform specific separations, to the corresponding chlorides, hydrocarbons and trimethylsilylethers.
Giumanini, Angelo G.,Tubaro, Franco
p. 755 - 761
(2007/10/02)

α-HYDROXYLATION OF CARBOXYLIC ACIDS AND AMIDES USING BIS(TRIMETHYLSILYL)PEROXIDE
Bis(trimethylsilyl)peroxide is shown to react with enolate anions derived from carboxylic acids and amides to give the corresponding α-hydroxy derivatives.
Pohmakotr, Manat,Winotai, Chanchai
p. 2141 - 2146
(2007/10/02)

Biotransformation of denaverine hydrochloride (Spasmalgan) in the rat
After oral application of denaverine hydrochloride to rats (200-250 mg/kg) 12 metabolites have been detected in urine.Besides the unchanged drug, 8 metabolites were identified by MS as 2,2-diphenyl-(2-dimethylaminoethyl)acetate (3), diphenylacetic (5) and benzilic acid (6), methyl- and ethyl acetate (7,11), methylbenzilate (10),N-demethyl-1 (12) and 3,3-diphenylmorpholin-2-one (13). 6 and metabonate 13 represent the main metabolic products.Compounds 7 and 11 indicate the metabolic pathway about an alkoxybenzilic acid (4).Phenols resp. conjugates were not detected.
Goeber, B.,Lisowski, Hannelore,Friese, Dagmar,Franke, P.
p. 493 - 495
(2007/10/02)

OXYGEN TRANSFER FROM PERCARBOXYLIC ACIDS AND ALKYL HYDROPEROXIDES TO (MESO-TETRAPHENYLPORPHINATO)IRON(III) AND -CHROMIUM(III)
The second order rate constants (kYOOH) for the reaction of (meso-tetraphenylporphinato)iron(III) chloride ((T-PP)FeIII(Cl)) with a series of percarboxylic acids and alkyl hydroperoxides (species YOOH) were determined in methanol by the trapping of the hypervalent iron-oxo porphyrin species with 2,4,6-tri-tert-butylphenol.The oxygen donors, TOOH, were chosen so that the leaving species, YOH, possessed pKa values spaced between 3.8 and 16.7.Values of kYOOH for oxidation of (TPP)CrIII(Cl) to (TPP)CrV(O) have been determined in dichloromethane by following the formation of ((TPP)CrIV)2O.The latter arises by non-rate-determining trapping of (TPP)CrV(O) by unreacted (TPP)CrIII(Cl).A plot of log kYOOH for (TPP)FeIII(Cl) versus the log of kYOOH for (TPP)CrIII(Cl) exhibits two linear portions.A slope of about unity is seen when YOOH represents percarboxylic acids.This reflects the similarity in mechanism for the reactions of percarboxylic acids with (TPP)FeIII(Cl) and (TPP)CrIII(Cl).Since phenylacetic acid is obtained as the product in the reaction of both (TPP)FeIII(Cl) and (TPP)CrIII(Cl) with phenylperacetic acid, the common mechanism is one of heterolytic scission of the percarboxylic acid O-O bond.With (TPP)CrIII(Cl), a linear free-energy plot of log kYOOH versus the pKa of the leaving YOH is shared by both percarboxylic acids and hydroperoxides.This finding is to be expected if oxygen transfer from hydroperoxides to (TPP)CrIII(Cl) shares with the percarboxylic acids the common mechanism of O-O bond heterolysis.A change in mechanism of oxygen transfer in the reactions of (TPP)FeIII(Cl) with percarboxylic acids and alkyl hydroperoxides is shown by the breaks in plots of the log kYOOH versus either the pKa of YOH or log kYOOH for (TPP)CrIII(Cl).The rate-limiting step on reaction of the less acidic alkyl hydroperoxides with (TPP)FeIII(Cl) is suggested to involve homolytic O-O bond scission to provide an intimate IV(OH)(X)-.O-alkyl> pair which may then dissociate as such or after H. transfer dissociate to (+.TPP)FeIV(O)(X) + HO-alkyl.Differentiation of mechanism on the basis of the products of YOH oxidation cannot be made.Details are discussed in the paper.The various linear free-energy plots exhibit a surprising independence of steric effects in the hydroperoxides.
Lee, William A.,Yuan, Lung-Chi,Bruice, Thomas C.
p. 4277 - 4283
(2007/10/02)

Oxidation of Alkenes and Sulphides with a Series of Hydroperoxides having Electron-withdrawing Substituents at the α-Position
The oxidations of alkenes and sulphides with a series of hydroperoxides, α-hydroperoxy-α-methoxyacetophenone (1), α-hydroperoxy-α,α-diphenylacetophenone (2), methyl α-hydroperoxy-α,α-diphenylacetate (3), and α-hydroperoxy-α,α-diphenylacetonitrile (4), were undertaken in a systematic fashion.The data revealed the following. (a) The reactions of electron-rich alkenes (11a and b) with hydroperoxides (1)-(4) are most likely to proceed by a mechanism similar to that with peracids, as do the oxidations of sulphides (5a-e). (b) For the reaction of less reactive alkenes (11f-k) with hydroperoxide (1) in the presence of oxygen, epoxidation by benzoylperoxyl radical contributes to a significantextent.The reaction with hydroperoxide (2) at 60 deg C also seems to proceed by a mechanism involving benzoylperoxyl radical, whereas a molecular epoxidation mechanism is important for the reaction at 30 deg C.Perhaps in accord with this, the reaction of 1,1-disubstituted ethylenes (11c-e) with hydroperoxides (1) and (2) results in the formation of considerable amounts of benzoylated products (13) and (14). (c) For the epoxidation with hydroperoxides (3) and (4), however, a molecular epoxidation process seems to predominate.The exception is the reaction of hydroperoxide (3) with (Z)-2-phenylbut-2-ene and (Z)-stilbene, having very poor reactivity, in which a peroxyl radical, produced by hydrogen abstraction from the hydroperoxide (3), plays an important role in the epoxidation.
Yamamoto, Hiroshi,Miura, Masahiro,Nojima, Masatomo,Kusabayashi, Shigekazu
p. 173 - 182
(2007/10/02)

Influence of Nitrogen Base Ligation and Hydrogen Bonding on the Rate Constants for Oxygen Transfer from Percarboxylic Acids and Alkyl Hydroperoxides to (meso-Tetraphenylporphinato>manganese(III) Chloride
Equilibrium constants for axial ligation of imidazole (ImH), N-methylimidazole (N-MeIm), 4'-(imidazo-1-yl)-acetophenone (NAcPhIm), 2,6-lutidine (2,6-Py), and 3,4-lutidine (3,4-Py) with (meso-tetraphenylporphinato)manganese chloride ((TPP)MnIIICl) have been determined.The rates of oxygen atom transfer from percarboxylic acids and alkyl hydroperoxides (YOOH) to the manganese(III) porphyrin in the presence of varying concentrations of the nitrogen bases were determined.For this purpose, 2,2-diphenyl-1-picrylhydrazine (DPPH) was employed as a trap for the generated higher valent oxo-manganese porphyrin species.From the equilibrium and kinetic data, there was then calculated the second-order rate constants for oxygen atom transfer from YOOH compounds to the species (TPP)MnIIICl, TPP(Cl)MnIIIN, and TPP(Cl)MnIIIN2 (where N = ImH, N-MeIm, and 3,4-Py).Only the percarboxylic acids exhibit measurable rate constants for oxygen transfer to (TPP)MnIIICl, whereas alkyl hydroperoxides and percarboxylic acids transfer oxygen to the TPP(Cl)MnIIIN species.Of the species TPP(Cl)MnIIIN2, reaction with YOOH compounds is seen only when N is imidazole.This is attributed to an equilibrium of the unreactive bis axially ligated TPP(Cl)MnIII(ImH)2 with the reactive isomeric mono axial-ligated complex Cl(1-)...H-Im...H-Im...MnIIITPP.Nitrogen base ligation of (TPP)MnIIICl provides minimally a 1E3 increase in the rate constants for oxygen transfer in methylene chloride.Linear free-energy plots of the log of the second-order rate constants for oxygen transfer from YOOH vs. the pKa of YOH establish that β1g for oxygen transfer in which heterolytic O-O bond scission is rate-determining is large and negative.The value of β1g when oxygen transfer involves rate-determining homolytic O-O bond scission is small and negative.
Yuan, Lung-Chi,Bruice, Thomas C.
p. 1643 - 1650
(2007/10/02)

Monooxygen Donation Potential of 4a-Hydroperoxyflavins As Compared with Those of a Percarboxylic Acid and Other Hydroperoxides. Monooxygen Donation to Olefin, Tertiary Amine, Alkyl Sulfide, and Iodide Ion
The reaction of the hydroxyperoxides diphenylhydroperoxyacetonitrile (4), methyl diphenylhydroperoxyacetate (5), and 5',6',7',8'-tetrahydro-4a'-hydroperoxy-3'-methylspiro-4'(3'H)-one (6) with I-, thioxane, and N,N-dimethylbenzylamine (DMBA) are first order in both hydroperoxide and substrate.For both 5 and 6, I3- is produced in 100percent yield.Product analysis for the reaction of 4, 5, and 6 with thioxane and DMBA established that the hydroxyperoxides are converted to the corresponding alcohols and that thioxane sulfoxide and N,N-dimethylbenzylamine N-oxide are formed.The reactions are quantitative.The reaction of 4 with I- proved to be complicated.The alcohol generated from 4 is the cyanohydrin of benzophenone.The dissociation of the benzophenone cyanohydrin product is competitive with I3- formation so that CN- produced in the dissociation reacts with I3- to yield ICN.Kinetic and thermodynamic analyses have provided the pertinent rate and equilibrium constants associated with the overall time course for reaction of 4 with I-.The second-order rate constant for the reaction of m-chloroperbenzoic acid (1) with I- has been determined and the second-order rate constant for reaction of 1 with thioxane was obtained from experiments in which thioxane and I- were employed as competitive substrates.The second-order rate constants for reaction of 1, 4, 5, and 6 with I-, thioxane, and DMBA were compared with like constants for the reactions of 4a-hydroperoxy-5-ethyl-3-methyllumiflavin (2), 1-carba-1-deaza-4a-hydroperoxy-5-ethyl-3-methyllumiflavin (3), t-BuOOH (7), and H2O2 (8).A log - log plot of the rate constants for monooxygen transfer from hydroperoxides to thioxane (kS) and to DMBA (kN) was found to be linear and of slope 1.0.The best line for the plot of log kS vs. the log of the rate constants for reactions with I- (kI) was of slope 1.1.The points for m-chloroperbenzoic acid were found to fit the log kS vs. log KI plot.These results show that the second-order rate constants for reactions of I-, thioxane, and DMBA are of like dependence on the electronic and steric characteristics of the hydroperoxides and percarboxylic acid 1.A linear free energy plot correlates the log of the second-order rate constants vs. pKa of YOH for oxygen transfer from YOOH = 1, 2, 4, 5, 7, and 8 (βlg = -0.6).In these reactions the 4a-hydroperoxyflavin 2 is the most efficient monooxygen donor of the hydroperoxides investigated, being 103 - 106 more reactive than t-BuOOH and ca. 103 less reactive than the peracid 1.The kinetics of epoxidation of 2,3-dimethyl-2-butene by the hydroperoxides 2 - 6 were invesigated by following both hydroperoxide disappearance and product formation.The results of these investigations, which include further reaction of epoxide with hydroperoxide to provide pinacol and 2,3-dimethyl-1-buten-3-ol, are discussed.Evidence for epoxidation of 2,3-dimethyl-2-butene ...
Bruice, Thomas C.,Noar, J. Barry,Ball, Sheldon S.,Venkataram, U. V.
p. 2452 - 2463
(2007/10/02)

Electrogenerated Bases. VI. Reaction of Electrogenerated Superoxide with Some Carbon Acids. II.
Electrogenerated superoxide and molecular oxygen were allowed to react sequentially with a number of esters, nitriles, N,N-dialkylamides, sulfones, and aliphatic nitro compounds.The α-methyl groups in these compounds bore aliphatic and/or aromatic substituents.When the electron-withdrawing group (EWG) of these carbon acids could be displaced intact (nitile 2, ArSO2 4, nitro) good to excellent yields of the corresponding carbonyl compounds could be obtained.The efficiency of the transformation depended upon the nature of the substituents: α,α-diphenyl (e.g., 2a) > α-methyl-α-phenyl (2b) > α,α-dimethyl.By conducting the electrolysis in the presence of acetic anhydride it was shown that the known conversion of phenylacetonitrile (2d) to benzoic acid did indeed proceed via benzaldehyde.When the EWG itself could be cleaved (esters 1, N,N-dialkyl-amides 3), this methodology produced α-hydroxylated compounds and the products resulting from fragmentation of the EWG and also from its complete displacement.The effects of the α-substituents were similar to those above.
Sugawara, M.,Baizer, M. M.,Monte, W. T.,Little, R. D.,Hess, U.
p. 509 - 518
(2007/10/02)

Studies on antidiabetic agents. III. 5-arylthiazolidine-2,4-diones as potent aldose reductase inhibitors
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Sohda,Mizuno,Imamiya,Tawada,Meguro,Kawamatsu,Yamamoto
p. 3601 - 3616
(2007/10/02)

On the analytics and the stability of denaverine hydrochloride
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Gober,Lisowski,Franke
p. 812 - 815
(2007/10/02)

2-ETHYLTHIO-1,3-BENZODITHIOL: A METHOXYCARBONYL ANION EQUIVALENT. A GENERAL SYNTHESIS OF α-HYDROXY ESTERS
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Fuji, Kaoru,Ueda, Masaru,Sumi, Kenzo,Fujita, Eiichi
p. 209 - 216
(2007/10/02)

Investigations of dithienylglycolic esters. V. Hydrolytic stability and preparation of some esters of glycolic acids
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Wallerberg,Ostman
p. 900 - 902
(2007/10/05)