Carboxylic acids inversion

Cyclic ketones from carboxylic acids Inverse Friedel-Crafts reaction... 

H-Azepine, 2,6,7-tri(methoxycarbonyl)-ring inversion, 7, 499 Azepine-1-carboxylic acid tricarbonylruthenium complexes, 7, 523 1 H-Azepine-2,3-dicarboxylic acid, 4,7-dihydro-6-phenyl-diethyl ester synthesis, 7, 539-540 1 H-Azepine-3,6-dicarboxylic acid... 

Azetidine, 7V-bromo-, 7, 240 Azetidine, AT-r-butyl- N NMR, 7, 11 Azetidine, AT-t-butyl-3-chloro-transannular nucleophilic attack, 7, 25 Azetidine, 3-chloro-isomerization, 7, 42 Azetidine, AT-chloro-, 7, 240 dehydrohalogenation, 7, 275 Azetidine, 7V-chloro-2-methyl-inversion, 7, 7 Azetidine, 3-halo-synthesis, 7, 246 Azetidine, AT-halo-synthesis, 7, 246 Azetidine, AT-hydroxy-synthesis, 7, 271 Azetidine, 2-imino-stability, 7, 256 Azetidine, 2-methoxy-synthesis, 7, 246 Azetidine, 2-methyl-circular dichroism, 7, 239 optical rotatory dispersion, 7, 239 Azetidine, AT-nitroso-deoxygenation, 7, 241 oxidation, 7, 240 synthesis, 7, 246 Azetidine, thioacyl-ring expansion, 7, 241 Azetidine-4-carboxylic acid, 2-oxo-oxidative decarboxylation, 7, 251 Azetidine-2-carboxylic acids absolute configuration, 7, 239 azetidin-2-ones from, 7, 263 synthesis, 7, 246... 

A variety of nucleophiles can be employed—e.g. carboxylic acids, phenols, imides, thiols, thioamides, and even /3-ketoesters as carbon nucleophiles. Of major importance however is the esterification as outlined above, and its use for the clean inversion of configuration of a chiral alcohol. 

Maleic acid, structure of, 753 Malic acid, structure of, 753 Walden inversion of, 359-360 Malonic ester, carboxylic acids from, 856-858... 

Of the studies which bear more particularly on electronic effects we mention first a study of the base-catalyzed H-D exchange in the 3-arylsulfonylbicyclo[2.2.1]hept-5-ene-2-carboxylic acids, cis (33), (35) and trans (34), and of the base-catalyzed inversion of the arylsulfonyl group in cis compounds (33) and (35)191. R comprised several meta- or para-... 

Nucleophilic substitutions of 0-activated 2-hydroxy carboxylic acids and esters, respectively, are well established, but little is known about the analogous reactions of activated cyanohydrins. Chiral 2-sulfonyloxynitriles, accessible from non-racemic cyanohydrins, have a relatively high configurational stability. They react with nucleophiles under very mild conditions under inversion of configuration (Scheme 8). ° ... 

D-a-Hydroxy carboxylic acids.1 These optically active acids can be prepared by a Sn2 reaction between the t-butyl esters of L-2-halo carboxylic acids and cesium p-nitrobenzoate, which proceeds with complete inversion. 

FIGURE 7.14 Reaction scheme leading to the inversion of configuration of some chiral carboxylic acids. 

Carboxylic acids, being weaker acids, react with la-a with inversion of configuration at the anomeric center to yield /2-0-acyl compounds (1,53). This mild and convenient method for 1 -0-acylation of carbohydrates is also useful for pharmacological drug modification (54) or for the resolution of carboxylic acids (53). 

If the 2-0-tosylated L-rhamnono-1,4-lactone (88) was boiled in water-dioxane the 2,5-anhydride (89) was obtained in good yield. The reaction time was 16 h in this case, compared to 2-4 h in the examples in which a primary tosyloxy group was substituted. The 2,5-anhydro-carboxylic acid 89 was isolated as the methyl ester, and was shown to have the L-gZuco-configuration [117]. Thus, a clean inversion at C-2 had taken place. 

Mendez Z, Anton RE, Salager JL (1999) Surfactant-oil-water systems near the affinity inversion. Part XI pH sensitive emulsions containing carboxylic acids. J Dispers Sci Technol 20 883-892... 

From 133-tiiazines 23 and 5-amino-4-imidazole-carboxylic acids 24 a variety of purines and purine nucleosides 25 have been prepared via an inverse electron demand Diels-Alder reaction <99JA5833>. 

The Pechmann and Knoevenagel reactions have been widely used to synthesise coumarins and developments in both have been reported. Activated phenols react rapidly with ethyl acetoacetate, propenoic acid and propynoic acid under microwave irradiation using cation-exchange resins as catalyst <99SL608>. Similarly, salicylaldehydes are converted into coumarin-3-carboxylic acids when the reaction with malonic acid is catalysed by the montmorillonite KSF <99JOC1033>. In both cases the use of a solid catalyst has environmentally friendly benefits. Methyl 3-(3-coumarinyl)propenoate 44, prepared from dimethyl glutaconate and salicylaldehyde, is a stable electron deficient diene which reacts with enamines to form benzo[c]coumarins. An inverse electron demand Diels-Alder reaction is followed by elimination of a secondary amine and aromatisation (Scheme 26) <99SL477>. 

Partially hydrogenated pyrrolopyridines have been prepared through a sequence that includes an alkynyl-substituted pyrimidine ring. An initial intramolecular inverse electron demand Diels-Alder reaction is followed by a cycloreversion to form a dihydropyrrolopyridine. The pyrimidine ring is generated in four steps starting with an alkynyl carboxylic acid (Scheme 7) <2004JOC9215>. 

When a carboxylic acid is used as the nucleophile, simple ester hydrolysis releases the alcohol, providing an inversion of alcohol stereochemistry. 

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