Hydroxy carboxylic acid esters

The most common O- and N-acylation procedures use acylating agents that are more reactive than caiboxylic acids or their esters. Carboxylic acid chlorides and anhydrides react rapidly with most unhindered hydroxy and amino groups to give esters and amides, respectively ... 

The alkylation of metalated imines, hydrazones, 4,5-dihydrooxazoles, 4,5-dihydroisoxazoles, 5,6-dihydro-4/7-1,2-oxazines and 2,5-dialkoxy-3,6-dihydropyrazines (i.e., azaenolates) is a commonly used method in asymmetric synthesis of enantiomerically enriched aldehydes, ketones, spiroacetals, amines, /J-oxo esters, carboxylic acids, lactones, 1,3-amino alcohols, /(-hydroxy ketones and amino acids. 

The secondary reduction of the terminal radical by Sml2 generates samarium alkyl species which are suitable for classical organometallic reactions, e.g. protonation, acylation, reactions with carbon dioxide, disulfides, diselenides, or the Eschenmoser salt. A broad variety of products is available (hydroxy-substituted alkanes, esters, carboxylic acids, thioethers, selenoethers, tertiary amines) by use of the double-redox four-step (reduction-radical reaction-reduction-anion reaction) route (Scheme 20) [73]. 

Oil maltha Carboxylic acids, hydroxy acids, and esters Acid value >20 Soap value 100-200 Iodine value 45-60 Products while distilling natural oil 2-5 % liquid soap, treated with soda or NaOH... 

Ox3 vaseline Mixed carboxylic acids, hydroxy acids, esters, and vaseline Acid value >55 Soap value 140 Moisture content <20 % Prepared by oxidation of vaseline Soda soap... 

Isocyanic acid, hydroxyalkyl ester, polyurethan Isocyanic acid, bivalent radical ester, polyurethan with diol N-Carboxylic acid, hydroxy-, polyester ... 

Also via Dicarboxylic Acids Section 312 (Carboxylic Acids - Carboxylic Acids). Hydroxy-esters Section 327 (Alcohol - Ester). Diols Section 323 (Alcohol - Alcohol)... 

Hydroxy acids compounds that contain both a hydroxyl and a carboxylic acid function have the capacity to form cyclic esters called lactones This intramolecular esterification takes place spontaneously when the ring that is formed is five or six membered Lac tones that contain a five membered cyclic ester are referred to as 7 lactones, their six membered analogs are known as 8 lactones... 

Ethers of benzenepentol have been obtained by Dakin oxidation of the appropriately substituted acetophenone. Thus, the oxidation of 2-hydroxy-3,4,6-ttimethoxyacetophenone and 2-hydroxy-3,4,5-ttimethoxyacetophenone with hydrogen peroxide ia the presence of alkali gives l,2-dihydroxy-3,4,6-ttimethoxybenzene and l,2-dihydroxy-3,4,5-ttimethoxybenzene, respectively further methylation of these ethers yields the pentamethyl ether of benzenepentol (mp 58—59 degC) (253). The one-step aromatization of myoinositol to produce esters of pentahydroxybenzene is achieved by treatment with carboxylic acid anhydrides ia DMSO and ia the presence of pyridine (254) (see Vitamins). 6-Alkyl- or... 

Benzimidazole-2-carboxylic acid decarboxylation, 5, 435 Benzimidazole-3-carboxylic acid, 1-hydroxy-ethyl ester synthesis, 6, 407 Benzimidazoles acidity, 5, 50, 385, 386 acylation, 5, 71, 391, 402, 417 2V-alkyl-... 

Benzo[b]furan-2-carboxylic acid, 6,6 -[(2-hydroxy-l,3-propanediyl)bis(oxy)]bis(3-hydroxy-diethyl ester trisodium salt trihydrate applications, 4, 709... 

Chroman-2-carboxylic acid, 2-hydroxy-4-oxo-ethyl ester synthesis, 3, 852... 

H-Chromene-4-carboxylic acid, 3-hydroxy-7-methoxy-ethyl ester... 

Chromone-2-carboxylic acid, 6,8-dibromo-7- hydroxy-ethyl ester... 

Chromone-5-carboxylic acid, 7-hydroxy-2-methyl-decarboxylation, 3, 711 Chromonecarboxylic acids decarboxylation, 3, 710 Chromone-2-carboxylic acids esters... 

Indole-2-carboxylic acid, 5-hydroxy-ethyl ester acylation, 4, 219... 

Pteridine-4-carboxylic acid, 2-hydroxy-ethyl ester, 3, 276... 

Pteridine-7-carboxylic acid, 6-oxo-synthesis, 3, 310 Pteridinecarboxylic acids structure, 3, 276-277 Pteridine-4-carboxylic acids ethyl ester hydrolysis, 3, 276 Pteridine-6-carboxylic acids properties, 3, 277 reactions, 3, 304 Pteridine-7-carboxylic acids properties, 3, 277 reactions, 3, 304 Pteridine-6,7-dicarboxylic acid properties, 3, 277 Pteridine-2,4-dione, 7-hydroxy-tautomerism, 3, 271... 

Pyrrole-2-carboxamide, N,N-dimethyl-conformation, 4, 194 Pyrrole-3-carboxamide, N,N-dimethyl-conformation, 4, 194 Pyrrolecarboxamides synthesis, 4, 242 Pyrrole-2-carboxamides synthesis, 4, 148, 360 Pyrrolecarboxylhydrazides Curtius degradation, 4, 362 Pyrrole-2-carboxylic acid, l-benzyl-3-hydroxy-ethyl ester... 

Pyrrole-2-carboxylic acid, 4,5-dimethyl-ethyl ester formylation, 4, 217 Pyrrole-2-carboxylic acid, 3-hydroxy-... 

The most common impurities are the corresponding acid and hydroxy compound (i.e. alcohol or phenol), and water. A liquid ester from a carboxylic acid is washed with 2N sodium carbonate or sodium hydroxide to remove acid material, then shaken with calcium chloride to remove ethyl or methyl alcohols (if it is a methyl or ethyl ester). It is dried with potassium carbonate or magnesium sulfate, and distilled. Fractional distillation then removes residual traces of hydroxy compounds. This method does not apply to esters of inorganic acids (e.g. dimethyl sulfate) which are more readily hydrolysed in aqueous solution when heat is generated in the neutralisation of the excess acid. In such cases, several fractional distillations, preferably under vacuum, are usually sufficient. 

Hydroxy-l,l-dioxo-l,2-dihydro-lX -benzo [e] [1,2] thiazine-3-carboxylic acid isopropyl ester (55)... 

The effect of a carboxy group is illustrated by the reactivity of 2-bromopyridine-3- and 6-carboxylic acids (resonance and inductive activation, respectively) (cf. 166) to aqueous acid under conditions which do not give hydroxy-debromination of 2-bromopyridine and also by the hydroxy-dechlorination of 3-chloropyridine-4-car-boxylic acid. The intervention of intermolecular bifunctional autocatalysis by the carboxy group (cf. 237) is quite possible. In the amino-dechlorination (80°, 4 hr, petroleum ether) of 5-carbethoxy-4-chloropyrimidine there is opportunity for built-in solvation (167) in addition to electronic activation. This effect of the carboxylate ion, ester, and acid and its variation with charge on the nucleophile are discussed in Sections I,D,2,a, I,D,2,b, and II,B, 1. A 5-amidino group activates 2-methylsulfonylpyridine toward methanolic am-... 

In the previous review (91YGK205, 99H1157), we reported that l-hydroxy-4-nitroindole forms active ester derivatives by reaction with carboxylic acids, which can be applied to acylation of various nucleophiles. To expand the scope of the reaction and obtain novel fungicidal compounds, an attempt has been made to prepare derivatives of wasabi phytoalexin 109 (98P1959). 

Fluorophenyl)-3-fluoro-2-hydroxy-6-oxo-6/7-pyrido[],2-n]pyrimidine-7-carboxylic acid (197, R = 4-FPh, R = H) was obtained from the 2-(4-methyl-]-piperazinyl)-7-ester derivative by the treatment with 1 N NaOH in an 1 1 mixture of H2O and THF at room temperature for 6h (95MIP1, 96JMC3070, 96MIP4, 96USP5580872). 

The respective amide was prepared from 7-substituted 5-oxo-2,3-dihydro-5//-pyrido[l,2,3-de]-l,4-benzoxazine-6-carboxylic acids via acid chlorides with different benzylamines (00M1P3). 6-Carboxamides were N-benzylated, and a side-chain phenolic hydroxy group was O-alkylated. 7-Aryl-5-oxo-2,3-dihydro-5//-pyrido[l, 2,3-r/e]-1,4-benzoxazine-6-carboxylic acid was obtained from the ethyl ester by alkalic hydrolysis. 

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