3-Nitro-2-naphthalenemethanol: a photocleavable protecting group for carboxylic acids

Photocleavable protecting groups are important in synthesis and caging. Among many such groups, 2-nitrobenzyl and related groups have been found useful in many applications. However, most of the known 2-nitrobenzyl-based caging chromophores show either low quantum yield or the photolysis wavelength is not suitable for various applications. In this paper, we report 2-nitro-3-naphthalenemethanol (NNM) as an efficient photocleavable protecting group for molecules containing a carboxylic function. NNM possesses photochemical properties better than the 2-nitrobenzyl chromophores as it is photoactivatable at 380 nm in aqueous medium (CH₃CN/H₂O, 3:2 v/v) showing the desired photochemistry. The carboxylic acids are efficiently photoreleased from NNM-based esters in almost quantitative yield.     

S-benzylthiouronium salts of some carboxylic acids,sulfonic acids,and phenols

116 S-Benzylthiouronium suits have been prepared and were, if possible, checked by titration with perchloric acid in glacial acetic acid on a semi-micro scale. Out of these, 110 are salts of carboxylic acids, 2 of snlfonic acids, and 4 of nitrophenols. The melting points determined according to a standard procedure are given.     

Facile O-arylation of phenols and carboxylic acids

[reaction: see text] A facile, transition-metal-free O-arylation procedure for phenols and aromatic carboxylic acids has been developed that affords good to excellent yields of arylated products under very mild reaction conditions. A methoxy-substituted aryl triflate affords O-arylated products in high yields with excellent regioselectivity. This chemistry tolerates a variety of functional groups.     

Silyl methallylsulfinates: efficient and powerful agents for the chemoselective silylation of alcohols, polyols, phenols and carboxylic acids

Alcohols, phenols and carboxylic acids are silylated with very good yields in the presence of silyl methallylsulfinates under non-basic conditions and with the formation of volatile co-products.     

A [5]HELOL analogue that senses remote chirality in alcohols, phenols, amines, and carboxylic acids

A route is developed to a structural analogue of [5]HELOL, a previously reported helically grooved sensor of remote chirality. It gives the material enantiomerically pure and in multigram quantities. The enantiomers of alcohols, phenols, amines, and carboxylic acids, even when their centers of chirality are remote from any functional groups, can be differentiated by 31P NMR spectroscopic analyses of their reaction products with the chlorophosphite of this material.     

Hydrothermal alkylation of phenols with alcohols in diluted acids

Diluted acids (typically 0.05 M HCl) are shown to be very effective media to promote the alkylation of phenols with activated alcohols under hydrothermal conditions (from 150 to 200 °C). These results are an elegant alternative to “usual” Friedel-Crafts alkylations avoiding the use of alkylchlorides as alkylating agents and the use of Lewis acidic promoters or concentrated acids but also shade some light on the processes occurring during the hydrothermal carbonisation (HTC) of biomass.     

Flophemesyl derivatives of alcohols,phenols, amines and carboxylic acids: Derivatives for mass spectrometric ion monitoring and structure determination

The flophemesyl (or pentafluorophenyldimethylsilyl) derivatives of representative alcohols, phenols, carboxylic acids and amines show rather simple spectra with a few abundant ions at high mass, characteristic of the parent compound and a few ions at low mass characteristic of the flophemesyl group. These derivatives are useful in the structure determination of simple compounds, and for the determination by single or multiple ion monitoring of known compounds at low levels.     

Reaction of trichlorides of phosphono carboxylic acids with acetylacetone,acetoacetic ester,and phenols

Reactions of trichloride of phosphono carboxylic acid with β-dicarbonyl compounds proceed at the active methylene group with the formation of the С-acylation product with a small admixture of the product of O-acylation. The C-acylation products undergo intramolecular condensation to form 1,2-oxophosphorines and compounds of the phosphate structure. The condensation of trichlorides with phenols proceeds selectively at the carbonyl carbon atom leading to C-phenyl esters. With more acidic phenols the splitting of the Р–С bond in the substitution product occurs.     

Condensation of nitriles of polyhalogenated carboxylic acids and benzonitrile with 2-hydroxy-4,6-dimethylacetophenone

Condensation of 2-hydroxy-4,6-dimethylacetophenone with trifluoro- and trichloroacetonitriles gives 2-amino-5,7-dimethyl-2-trifluoro(trichloro)methyl-4-chromanones. The condensation with 2,2,3,3-tetrafluoropropionitrile, perfluorovaleronitrile, and benzonitrile stops at the stage of formation of the corresponding enamines. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 362–363, February, 1998.     

Characteristics of the reaction of manganese metal with phenols,alcohols, water,and their mixtures with each other and with carboxylic acids in a bead mill

The macrokinetic relationships of the mechanochemical reaction of manganese with phenols, alcohols, water, and their mixtures with each other and with carboxylic acids taken in various molar ratios but, in some cases, in total stoichiometric amount were examined.     

Kinetic resolution of racemic alcohols with chiral carboxylic acids and dicyclohexylcarbodiimide

The DCC-esterification method has been used to kinetically resolve racemic mixtures of alcohols. With simple chiral carboxylic acids, such as O-aryl lactic acids, in the presence of various basic catalysts, mixtures of the enantiomerically enriched alcohols (e.e. <50%) and the corresponding esters (d.e.<70%) have been obtained.     

Regio- and stereoselective C-2 and C-3 cleavage of 2-(1-aminoalkyl)aziridines with alcohols, carboxylic acids, and sodium iodide

Ring opening of nonactivated aziridines 1 using several nucleophiles, such as alcohols, carboxylic acids, and sodium iodide, is described. Depending on the nucleophile used, aziridines 1 are cleaved at C-3 or C-2 with total regio- and stereoselectivity, affording chiral 2-alkoxy-1,3-diamines 2 with alcohols, or O-acylated-1-hydroxy-2,3-diamines 6 with carboxylic acids in moderate or high yield. In the case of the aziridines derived from phenylalanine, treatment with NaI afford trans-4-phenylbut-3-en-1,2-diamines 9, generating the alkene with total diastereoselectivity. Mechanisms have been proposed to explain these reactions.     

Microdetermination of phenols, carboxylic acids and phenolic acids by potentiometric and visual titrations in dimethylformamide

Potentiometric titration of phenols with sodium methoxide in dimethylformamide, with a glass-calomel electrode system, is limited to monohydric phenols substituted with electron-attracting groups and dihydric phenols in which the two -OH groups are substituted in isolated benzene rings. Brilliant Orange has proved to be a suitable indicator in the titration of all types of mono- and dihydric phenols. Titan Yellow is recommended as indicator for the titration of carboxylic acids. Simultaneous visual titration of -OH and -COOH groups is also described. A detailed study with 62 structurally different compounds covering the various groups is reported, and a suitable procedure for the microdetermination of each class of these compounds with an error of +/- 0.2% absolute or less is presented.     

Efficient photolytic esterification of carboxylic acids with alcohols in perhalogenated methane

Condensation of carboxylic acids and alcohols to give esters was accomplished with selectivity under photolytic conditions in 66-99% yields by use of CCl₄ or BrCCl₃ at room temperature.     

Reaction of 2-methylene-3-oxoquinuclidine with water,alcohols, and organic acids

2-Methylene-3-oxoquinuclidine (I) reacts with alcohols without acidic or alkaline catalysts to give 2-alkoxymethyl-3-oxoquinuclidines. In the case of protonation of I by weak acids (benzoic and barbituric acids) water molecules do not add to the double bond. Condensed heterocyclic systems that include the quinuclidine ring were obtained on the basis of 2-hydroxymethyl-3-hydroxy-²-dehydroquinuclidine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 948–951, July, 1981.     

Gal3 Catalyzed Tetrahydropyranylation of Alcohols and Phenols

In dichloromethane, the nucleophilic addition of alcohols or phenols to 3,4-dihydro-2H-pyran (DHP) was catalyzed effectively by gallium triiodide which was generated in situ by the reaction of gallium metal and iodine to give the corresponding tetrahydropyranyl acetals in good to excellent yields.     

Reactions of dichloromaleimides with alcohols,phenols, and thiols

Thiols react with dichloromaleimides in the presence of base to give 2,3-bis[alkyl(aryl)-mercapto]maleimides. Alcohols and phenols in equivalent amounts give 2-alkyl(aryl)oxy-3-chloromaleimides. With two equivalents, phenols give 2,3-bis(aryloxy)maleimides, but alcohols give 2-chloro-3,3-dialkoxysuccinimides in protic solvents and dimeric compounds in aprotic solvents.     

Cyclic mechanism in the trapping of carbonyl oxides with alcohols and carboxylic acids

The reaction of diphenylcarbonyl oxide with alcohols and carboxylic acids, which has been classified as a nucleophilic trapping, is shown to be in the reactivity order: AcOH ? MeOH > CF₃CH₂OH > EtOH ? t-BuOH. A laser-flash spectroscopy indicated that the reaction of carboxylic acids is very fast, that is, one-tenth of the diffusion rate. These results suggest that the hydroxyl compounds react as an acid and a nucleophile at the same time and the major reaction is via the seven- and five-membered cyclic mechanism for RCO₂H and ROH, respectively.