Dicarboxylic esters, reduction

Isothiazole-4,5-dicarboxylic acid, 3-phenyl-dimethyl ester synthesis, S, 150 Isothiazole-5-glyoxylic acid ethyl ester reduction, 6, 156 Isothiazole-4-mercurioacetate reactions, 6, 164 Isothiazole-5-mercurioacetate reactions, 6, 164 Isothiazoles, 6, I3I-I75 acidity, 6, 141 alkylation, 6, 148 aromaticity, S, 32 6, 144-145 basicity, 6, I4I biological activity, 6, 175 boiling points, 6, I43-I44, 144 bond fixation, 6, 145 bond orders, 6, I32-I34 calculated, 6, 133 bromination, S, 58 6, 147 charge densities, 6, 132-134 cycloaddition reactions, 6, 152 desulfurization, S, 75 6, 152 deuteration, S, 70... 

Claisen ester condensation, 6, 279 Thiazolecarboxylic acid chlorides reactions, 6, 279-280 Thiazolecarboxylic acid hydrazides synthesis, 6, 280 Thiazolecarboxylic acids acidity, 6, 279 decarboxylation, 6, 279 reactions, S, 92 6, 274 Thiazole-2-carboxylic acids decarboxylation, S, 92 Thiazole-4-carboxylic acids stability, S, 92 Thiazole-5-carboxylic acids decarboxylation, S, 92 Thiazole-4,5-dicarboxylic acid, 2-amino-diethyl ester reduction, 6, 279 Thiazole-4,5-dicarboxylic acids diethyl ester saponification, 6, 279 Thiazolediones diazo coupling, 5, 59 Thiazoles, 6, 235-331 ab initio calculations, 6, 236 acidity, S, 49 acylation, 6, 256 alkylation, S, 58, 73 6, 253, 256 analytical uses, 6, 328 antifogging agents... 

Formation of cycloalkane-1,2-dicarboxylate esters by reduction of dibromoalkanedicarboxylate esters at a platinum cathode in tetrahy-drofuran. Data from ref. [109]... 

Tire aldehyde has been shown to be an intermediate in reduction of aromatic esters in both acid [149] and alkaline solutions [148]. It can be trapped in good yield in the form of an acetal by reduction of benzoate esters in acetonitrile in the presence of chlorotrimethylsilane [150]. Intermediates in the reduction of diphcnyl-2,2 -dicarboxylate esters undergo a cyclization reaction to form 5,6-dthydroxyph-enanthrene [148]. 

Dicarboxylic esters in the presence of Na in ether or in benzene (carcinogen) cyclize to furnish not (3-keto esters but instead a-hydroxy ketones (acyloins). This acyloin condensation involves reductive dimerization of a ketyl radical anion (see Chapter 9). ... 

Intramolecular free radical cyclization of dicarboxylic esters leads to a-hydroxy ketones (acyloins). Reductive coupling of dicarbonyl compounds provides 1,2-diols ipinacols) and further reaction of these yields cycloalkenes (McMurry reaction). These cyclization reactions are especially valuable for the preparation of medium and large rings that are not readily accessible by other methods. 

A mixture of lupinine and epilupinine is obtainable by the following series of reactions. The betaine XXVI on cyclic hydrogenation and subsequent decarboxylation with 20 % hydrochloric acid gives a mixture of epimeric lupininic acids (XXIX). The dicarboxylic ester XXVIII is also obtained by the mercuric acetate dehydrogenation of the piperidine derivative XXX and by the alkylation of monomeric piperideine with a y-bromopropylmalonic ester. The last route is presumably a first Mannich condensation followed by an alkylation. Hydrolysis of the malonic esters, decarboxylation (XXIV), esterification, and reduction with lithium aluminum hydride complete the synthesis of a mixture which consists of 80% dZ-epilupinine and 20% dMupinine. Thermal... 

Ester reduction. A method for the conversion of dicarboxylic acids to CD-hydroxycarboxylic acids involves formation and reduction (with NaBH ) of dilactones in which the two carbonyl residues are linked by tm OCH2O chain. Arylpyruvic esters can be reduced to either the a-hydroxy esters or 1,2-diols. ... 

The total synthesis of (+ )-dehydroheliotridine (4), a toxic metabolite of the pyrrolizidine alkaloids (e.g. lasiocarpine and heliotrine), has also been described.2 The pyrrole ring was obtained by reaction of l,6-dihydroxy-2,5-dicyanohexa-l,3,5-triene-l,6-dicarboxylic ester (5) with j3-alanine, which afforded the N-substituted pyrrole ester (6), together with the appropriate amide of oxalic acid. Careful hydrolysis of (6) with dilute alkali afforded the related tricarboxylic acid, which was converted, by Dieckmann cyclization, hydrolysis and decarboxylation, into the keto-acid (7). Esterification of (7) with diazomethane, followed by reduction with lithium aluminium hydride, finally afforded ( )-dehydroheliotridine (4), identical, except in optical rotation, with dehydroheliotridine obtained earlier by Culvenor et al.3... 

The reductive dimerization of cyclopropane-1,1-dicarboxylic esters using SmI2/THF has also been reported (Scheme 34). In this case, the addition of... 

Reduction. At -78°, selective reduction of l-alkylindole-2,3-dicarboxylic esters at the C-2 substituent (to a CHO group) by Dibal-H is observed. Generally, the ester to aldehyde conversion can be performed at 0° with alkali metal diisobutyl(t-butoxy)aluminum hydride, which is formed by adding t-BuOM (M = Na, Li) to Dibal-H in THF. ... 

Imamoto et al. have reported a samarium(II) iodide promoted reductive ring opening of cyclopropane-1,1-dicarboxylie esters for the synthesis of 8-lactones [121] (Scheme 74). Treatment of various cyclopropane-1,1-dicarboxylate esters 328 with a variety of ketones 329 in the presence of samarium iodide and a catalytic amount of tris(dibenzoylmethiodo)iron(III) gave a diverse array of 2-methoxycarbonyl-5,5-disubstituted 8-lactone 330 in good yields. The use of a catalytic amount of the iron complex was imperative to accelerate the reductive ring opening of the cyclopropane. 

IsoxazoIidine-3,3-dicarboxylic acid, 2-methoxy-dimethyl ester reaction with bases, 6, 47 Isoxazolidine-3,5-diones synthesis, 6, 112, 113 Isoxazoli dines conformation, 6, 10 3,5-disubstituted synthesis, 6, 109 oxidation, 6, 45-46 PE spectra, 6, 5 photolysis, 6, 46 pyrolysis, 6, 46 reactions, 6, 45-47 with acetone, 6, 47 with bases, 6, 47 reduction, 6, 45 ring fission, S, 80 spectroscopy, 6, 6 synthesis, 6, 3, 108-112 thermochemistry, 6, 10 Isoxazolidin-3-ol synthesis, 6, 111 Isoxazolidin-5-oI synthesis, 6, 111... 

Dicarboxylic acids have been prepared by the stepwise acylation and Wolff-Kishner reduction of thiophene or di-2-thienylmethane with ester chlorides of dicarboxylic acids. Another method consists of the AICI3 catalyzed acylation of w-phenylalkylthiophenes which occurs both in the free thiophenic position and in the para position of the ring (226). Hypochlorite oxidation and desulfurization then give diacides such as (227)... 

In this section primarily reductions of aldehydes, ketones, and esters with sodium, lithium, and potassium in the presence of TCS 14 are discussed closely related reductions with metals such as Zn, Mg, Mn, Sm, Ti, etc., in the presence of TCS 14 are described in Section 13.2. Treatment of ethyl isobutyrate with sodium in the presence of TCS 14 in toluene affords the O-silylated Riihlmann-acyloin-condensation product 1915, which can be readily desilylated to the free acyloin 1916 [119]. Further reactions of methyl or ethyl 1,2- or 1,4-dicarboxylates are discussed elsewhere [120-122]. The same reaction with trimethylsilyl isobutyrate affords the C,0-silylated alcohol 1917, in 72% yield, which is desilylated to 1918 [123] (Scheme 12.34). Likewise, reduction of the diesters 1919 affords the cyclized O-silylated acyloin products 1920 in high yields, which give on saponification the acyloins 1921 [119]. Whereas electroreduction on a Mg-electrode in the presence of MesSiCl 14 converts esters such as ethyl cyclohexane-carboxylate via 1922 and subsequent saponification into acyloins such as 1923 [124], electroreduction of esters such as ethyl cyclohexylcarboxylate using a Mg-electrode without Me3SiCl 14 yields 1,2-ketones such as 1924 [125] (Scheme 12.34). 

Scheme 12.19 illustrates some cases in which ozonolysis reactions have been used in the course of syntheses. Entries 1 to 4 are examples of use of ozonolysis to introduce carbonyl groups under reductive workup. Entries 5 and 6 involve oxidative workup and give dicarboxylic acid products. The reaction in Entry 7 is an example of direct generation of a methyl ester by methoxide trapping. 

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