Acids In Excellent Yields Research Articles

Methanolysis of ortho- and para-formylbenzenesulfonates in basic media: evidence for the intramolecular nucleophilic catalysis by the carbonyl group

Methanolysis of p-methoxyphenyl 2-formylbenzenesulfonate, in the presence of anhydrous potassium carbonate at ambient temperature gives the dimethyl acetal of 2-formylbenzenesulfonic acid in excellent yield. p-Methoxyphenyl 4-formylbenzenesulfonate under identical conditions remains unaffected. These results provide evidence for the catalytic involvement of the neighbouring aldehyde carbonyl group and operation of intramolecular nucleophilic catalysis during the nucleophilic substitution at sulfonyl sulfur.

Lewis Acid Promoted, Nickel Cyanide Catalyzed Double Insertion of Carbon Monoxide in Reaction with Alkynols Using PEG-400 as a Phase-Transfer Agent. Role of Phase-Transfer Catalysts in Determining the Stereochemistry of the Reaction

Alkynols can be converted to 2-alkylidenebutanedioic acids in excellent yield by Ni(CN)2-catalyzed reactions in toluene and 5.0 M aqueous NaOH under atmospheric pressure of CO at 95 °C, with polyethylene glycol (PEG-400) as the phase-transfer agent. This process is accelerated by the addition of certain Lewis acids, including CeCl3·7H2O, FeCl3, and LaCl3· 7H2O. The extent of conversion and the selectivity of the reaction are sensitive to the concentration of base. The stereochemistry for the formation of diacids using PEG-400 as the phase transfer agent is opposite to that found with quaternary ammonium salts. E-unsaturated diacids are the dominant products in all cases when PEG-400 is used as the phase-transfer agent.

Diazotization of Methyl 3‐Amino‐7‐Isopropyl‐2‐Methoxyazulene‐1‐Carboxylate and its 5‐Isopropyl Isomer‐ a Convenient Synthesis of 1,2‐Azulenequinone Derivatives

AbstractMethyl 3‐amino‐2‐methoxy‐7‐isopropylazulene‐l‐carboxylate(8a) and its 5‐isopropyl isomer (8b) were synthesized by reduction of the 3‐nitro derivatives (7a,b) with zinc/acetic acid in excellent yields. 7a and 7b were prepared by nitration and methylation of methyl 7‐isopropyl‐2‐hydroxyazulene‐l‐carboxylate (5a) and methyl 5‐isopropyl‐2‐hydroxyazulene‐l‐carboxylate (5b), respectively. Diazotization of 8a with sodium nitrite in trifluoroacetic acid at 0 °C gave methyl 5‐isopropyl‐1,2‐azulenequinone‐3‐carboxylate (9a) in 91% yield. Similar reaction of 8b gave the corresponding methyl 7‐isopropyl‐1,2‐azulenequinone‐3‐carboxylate (9b) in 93% yield. No evidence for the formation of l‐diazo‐1,2‐azulenequinones was obtained.

Alkane Oxidation with Molecular Oxygen Using a New Efficient Catalytic System: N-Hydroxyphthalimide (NHPI) Combined with Co(acac)(n)() (n = 2 or 3).

A novel class of catalysts for alkane oxidation with molecular oxygen was examined. N-Hydroxyphthalimide (NHPI) combined with Co(acac)(n)() (n = 2 or 3) was found to be an efficient catalytic system for the aerobic oxidation of cycloalkanes and alkylbenzenes under mild conditions. Cycloalkanes were successfully oxidized with molecular oxygen in the presence of a catalytic amount of NHPI and Co(acac)(2) in acetic acid at 100 degrees C to give the corresponding cycloalkanones and dicarboxylic acids. Alkylbenzenes were also oxidized with dioxygen using this catalytic system. For example, toluene was converted into benzoic acid in excellent yield under these conditions. Ethyl- and butylbenzenes were selectively oxidized at their alpha-positions to form the corresponding ketones, acetophenone, and 1-phenyl-1-butanone, respectively, in good yields. A key intermediate in this oxidation is believed to be the phthalimide N-oxyl radical generated from NHPI and molecular oxygen using a Co(II) species. The isotope effect (k(H)/k(D)) in the oxidation of ethylbenzene and ethylbenzene-d(10) with dioxygen using NHPI/Co(acac)(2) was 3.8.

Electrocatalytic reduction of benzoylformic acid mediated by methyl viologen

Benzoylformic acid is reduced electrocatalytically to mandelic acid in excellent yield in the presence of methyl viologen of which two-electron reduction product behaves as active reductant, and the presence of β-CD or its derivative induces enantioselectivity.

Synthesis and Diazotization of Diethyl 6‐Amino‐2‐Hydroxyazulene‐1,3‐Dicarboxylate and Its 2‐Acetoxyl Derivative

AbstractDiethyl 6‐amino‐2‐hydroxyazulene‐1,3‐dicarboxylate (6a) and 2‐acetoxyl derivative (6b) were synthesized by reduction of the 6‐azido derivatives (5a,b) with zinc/acetic acid in excellent yields. 5a and 5b were prepared by azidation of diethyl 2‐acetoxy‐6‐bromoazulene‐1,3‐dicarboxylate (4). Diazotization of 6a with sodium nitrite in the presence of concentrated sulfuric acid in dioxane gave diethyl 2‐hydroxy‐ (7a), 2,6‐dihydroxy‐ (8a), and 2‐hydroxy‐6‐[2‐(2‐hydroxyethoxy)ethoxy]‐azulene‐1,3‐dicarboxylates (9a), in 5, 35 and 20% yields, respectively. Similar reaction of 6b gave the corresponding acetates 7b, 8b, and 9b, compounds of the same type from 6a. No evidence for the formation of 6‐diazo‐1,3‐diethoxycarbonyl‐2(6H) azulenone (2b) was obtained in the employed reaction conditions.

Synthesis of 1,2-disubstituted benzenes and biphenyls from phthalic acids through electroreduction followed by electrocyclic reaction with alkynes

Various substituted 1,2-dihydrophthalic acids were synthesized by electroreduction of phthalic acids in excellent yields. The electrocyclic reaction of 1,2- dihydrophthalic acids or the methyl ester with alkynes gave 1,2-disubstituted benzenes and biphenyls in good yields together with fumaric acid or methyl fumarate.

Chlorotrimethylsilane Mediated Formation of ω-Allyl Esters of Aspartic And Glutamic Acids

Abstract The protection of the ω-carboxylic function of aspartic and glutamic acids by an allyl ester is advantageous because of its orthogonality with most protecting groups and its compatibility with a number of reagents. In this communication we describe a simple method using chlorotrimethylsilane in the presence of allyl alcohol which gives exclusively the ω-allyl esters of both aspartic and glutamic acids in excellent yield.

New and Efficient Conversion of Benzoic Acids into Salicylic Acids via Copper Mediated Hydroxylation Process

N-benzoyl-2-methylalanines , obtained through condensation of aroyl chlorides with sodium 2-methylalaninate are ortho-hydroxylated by the nex Cu(0)/O 2 /trimethylamine N-oxide system. Acid hydrolysis of the so-obtained salicylamides provides salicylic acids in excellent yield. When the substrate contains three electron-releasing groups the yields are moderate

Facile Synthesis of 1,1′-Binaphthyl-2-carboxylates via Nucleophilic Aromatic Substitution of 1-Methoxy-2-naphthoic Esters by 1-Naphthyl Grignard Reagents

Abstract Grignard reagents formed from 1-bromonaphthalenes smoothly displaced the 1-methoxyl group of 1-methoxy-2-naphthoic esters to provide a facile route to 1,1′-binaphthyl-2-carboxylic acids in excellent yields; the reaction of (S)-1-phenylethyl esters caused asymmetric induction in the joining of the two naphthalene rings in up to 51% optical yield.

Chromium carbene complexes in the synthesis of molecules of biological interest

Abstract

ChemInform Abstract: A Mild and Selective Method of Ester Hydrolysis.

AbstractThe esters (I) and diesters (III) are treated with Dowex 50 in refluxing water to give the corresponding acids (II) and (IV) respectively.

A mild and Selective Method of Ester Hydrolysis

Abstract Carboxylic esters, when refluxed in an aqueous suspension of Dowex-50, furnish the corresponding carboxylic acids in excellent yields. Tertiary ester and nitriles remain unaffected under this condition and β-keto esters undergo smooth decarboxylations.

Regiospecific Oxidation of Methyl Groups in Dimethylanisoles

Dimethylanisoles in which one of the methyl groups is meta and the other is ortho or para are regiospecifically oxidized in high yield to the corresponding ortho- and para-substituted aldehydes by copper (II) and peroxydisulfate. Subsequent oxidation of the aldehydes with sodium chlorite furnishes the corresponding acids in excellent yield.

A NEW AND CONVENIENT ROUTE TO THE AMIDES OF α-AMINO ACIDS AND α-HYDROXY ACIDS BY MEANS OF THE PALLADIUM CATALYZED FACILE CLEAVAGE OF 3-SUBSTITUTED-4-ARYLAZETIDIN-2-ONES

Abstract 3-Substituted-4-arylazetidin-2-ones were found to be cleaved selectively at the N–C4 bond by the hydrogenolysis on palladium catalyst to give the corresponding amides of α-amino acids or α-hydroxy acids in excellent yields.

Irradiation of diaryl phosphates. A potentially useful new reaction for the preparation of monoalkyl phosphates

U.v. irradiation of a series of simple dianisyl alkyl phosphates provided the corresponding monoalkyl phosphoric acids in excellent yields.

Allenes. Part XVIII. The synthesis of allenic amino-acids from allenic bromides and diethyl formylaminomalonate

The preparation of six allenic amino-acids from 1-bromoalka-1,2-, -2,3-, and -3,4-dienes and diethyl formylamino-malonate is described. Iodoallene gave only the formylamino(prop-2-ynyl)malonate, which on hydrolysis gave prop-2-ynylglycine. 5-Bromopent-3-en-1-yne gave 2-aminohept-4-en-6-ynoic acid in excellent yield.

1-acyl-indoles. II. A new syntheses of 1-(p-chlorobenzoyl)-5-methyoxy-3-indolyacetic acid and its polymorphism.

1-(p-Chlorobenzoyl)-2-methyl-5-methoxy-3-indolylacetic acid, a potent antiinflammatory drug, was directly prepared from N1-(p-chlorobenzoyl)-p-methoxyphenyl-hydrazine hydrochloride and levulinic acid in excellent yield by the new method. The recrystallization of 1-(p-chlorobenzoyl)-2-methyl-5-methoxy-3-indolylacetic acid from solvents gave crystals of polymorphism -α, β, and γ-types.