Reduction of carboxylic esters to aldehydes with diisobutylaluminum hydride

Summary Some aliphatic and aromatic carboxylic esters were reduced to the corresponding aldehydes in high yield with diisobutylaluminum hydride at low temperature (–70°).     

Synthesis of carboxylic esters from aldehydes using metal carbonyl anions,part 2. Dimerization of aldehydes to carboxylic esters catalyzed by disodium pentacarbonylchromate,na2[cr(co)5]

Na₂[Cr(CO)₅] (1) was found to be an efficient catalyst for the dimerization of aldehydes to carboxylic esters. Several aromatic aldehydes including furfural gave the corresponding esters in good yields. This reaction also proceeded intramolecularly to give phthalide from phthalaldehyde. Compared with M₂[Fe(CO)₄] (M = Na, K), 1 was found to be a more efficient catalyst for this reaction. However, aliphatic aldehydes gave aldolcondensation products instead of the corresponding esters. In the reactions of p-substituted benzaldehydes with 1, the reactivity decreased with the increase of the electron-releasing ability of the substituents. However, even p-anisaldehyde, which hardly reacted with M₂[Fe(CO)₄], reacted with 1 to give the ester in moderate yield. The reaction mechanism, including the nucleophilic attack of the pentacarbonylchromate dianion on the carbonyl carbon, is discussed.     

Stereoselective generation of vicinal stereogenic quaternary centers by photocycloaddition of 5-methoxy oxazoles to alpha-keto esters: synthesis of erythro beta-hydroxy dimethyl aspartates

The photocycloaddition of methyl pyruvate and methyl phenylglyoxylate, respectively, to 5-methoxy oxazoles bearing additional substituents at C-2 and C-4 leads to bicyclic oxetanes 2 and 3 with high to moderate (exo) diastereoselectivity that can be easily ring-opened to give bis-quaternary aspartic acid diester derivatives 4 and 5.     

Synthesis of gross-conjugated polyenic dialdehydes and carboxylic acid esters

Conclusions Methylenemalonaldehyde was used in a convenient method for the synthesis of 4-aryl-and 4-heteroarylmethylenehepta-2,5-diene-1,7-dials and dimethyl esters of 6-aryl- and 6-heteroarylmethyleneundeca-2,4,7,9-tetraene-1,11-dioic acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2614–2616, November, 1987.     

Electron ionization mass spectral fragmentation of C19 isoprenoid aldehydes and carboxylic acid methyl and trimethylsilyl esters

The electron ionization (EI) mass spectra of saturated and alpha,beta-unsaturated C(19) isoprenoid aldehydes and carboxylic acid methyl and trimethylsilyl esters are reported. Different pathways are proposed in order to explain the main fragmentations observed. The conjugated double bond migrates more or less readily before gamma-hydrogen rearrangement according to the structure of the considered compound. Configurations of the double bond of alpha,beta-unsaturated C(19) isoprenoid aldehydes and fatty acid methyl and trimethylsilyl esters can be easily determined thanks to the peaks at m/z 97, 127 and 185, respectively, which are much more abundant in the mass spectra of the Z isomers owing to the formation of a cyclic ion. In the case of trimethylsilyl esters, subsequent fragmentation of the cyclic ion at m/z 185 affords two other diagnostic ions at m/z 95 and 169.     

Synthesis of carboxylic acid esters in the presence of micro- and mesoporous aluminosilicates

The catalytic properties of zeolites HY, HBeta, and HZSM-12 and of mesoporous amorphous aluminosilicate in liquid-phase esterification of aliphatic (monobasic C₁–C₁₈, dibasic C₆, C₁₀) and aromatic (benzoic, trimellitic, phthalic) carboxylic acids with butanol were studied. Zeolite HBeta appeared to be the most active catalyst. Procedures were developed for preparing esters in the presence of zeolitic catalyst HBeta, ensuring 100% selectivity of ester formation at 90–98% conversion of the acid.     

Synthesis of 1-arylcytosine-5-carboxylic acid esters

A reaction of alkyl 2-(diaminomethylidene)-3-oxoalkanoates with arylisocyanates leads to the formation of the corresponding ureas, which upon the action of Na alkoxides cyclize to 1-aryl-6-R-cytosine-5-carboxylates. The latter reacting with arylisocyanates according to the similar scheme give rise to 3,6-diaryl-5-methylpyrimido[4,5-d]pyrimidine-2,4,7(1H,3H,6H)-triones.     

Synthesis and hydrolysis of 5-nitrofurandicarboxylic acid esters

A method of the hydrolysis of 5-nitrofurandicarboxylic acid testers is proposed. The difference in the reactivities of the ester groups attached to the furan ring and in the side chain is explained by the effect of steric factors. It is shown that the direction of hydrolysis is determined by the structure of the alkyl substituent in the ester group. The mechanisms of the hydrolysis are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 311–313, March, 1977.     

Synthesis of vinyl esters of organosilicon carboxylic acids

Conclusions The vinylation of -silicon-containing carboxylic acids by acetylene under the influence of zinc and cadmium salts was investigated. A method was found for producing organosilicon complex vinyl esters.     

Reactions of aromatic aldehydes and their acetals with phosphorous acid esters

Russian Journal of General Chemistry -     

Synthesis of amino acid esters by papain

A wide range of N-Boc-amino add esters were synthesized from N-Boc-amino acids and alcohol using papain as catalyst. Suitable biphasic reaction mixtures were found for most amino acids to achieve high yield of ester synthesis. With N-Boc-L-aspartic and glutamic adds only the a carboxyl group is esterified, without racemisation.     

Synthesis of some thioglycidyl esters of monobasic carboxylic acids

Thioglycidyl esters of monobasic carboxylic acids were synthesized by thioepoxidation of glycidyl esters of thiourea.Translated from Khimiya Geterotsiklicheskikh Soedinenii No. 5, pp. 588–590, May, 1989.     

Sequential resolution of ethyl 3-aminobutyrate with carboxylic acid esters by Candida antarctica lipase B

The reactions of ethyl 3-aminobutyrate 1 with carboxylic acid esters, catalyzed by lipases from Candida antarctica, Pseudomonas cepacia and Pseudomonas fluorescens, have been studied. The reactions take place on the amino and ester functions of the substrate provided that the alkyl group of the achiral ester differs from ethyl. This property has been exploited for the Candida antarctica lipase B-catalyzed resolution of 1 in butyl butyrate, leading to the unreacted enantiomer (S)-1 and butyl 3-aminobutyrate, and to the butanamide of butyl (R)-3-aminobutyrate.     

Synthesis of γ-diketo carboxylic acids and their esters

Conclusions We have developed a method of obtaining -diketocarboxylic acids and their esters by acid hydrolysis of esters of-(5-methylfuryl)propionic acids.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 214–215, January, 1968.     

Efficient allylation of aldehydes promoted by carboxylic acids

A variety of carboxylic acids have been screened for mediating the allylation of aldehydes with allytributyltin in different solvents. A novel, general, and practical method of allylation of aldehydes promoted by carboxylic acids under mild reaction conditions has been developed. Among them, p-nitrobenzoic acid afforded high to quantitative yields of the homoallylic alcohol products, and can be easily recovered after workup by aqueous HCl. Glyoxylic acid self-catalyzed the allylation without adding any other promoter or catalyst to give the corresponding allylation product in good yield. The regioselectivity of the crotylation of aldehydes is tunable by controlling the acidity of the carboxylic acids. The crotylation of aldehydes produced the alpha-adduct as major products in moderate to good yields with CF(3)CO(2)H as a promoter. A possible mechanism for the allylation is also discussed.     

Synthesis of 1,3,5-triazine derivatives on the basis of carboxylic acid imino esters (review)

Data on methods for the synthesis of 1,3,5-triazine derivatives by cyclotrimerization and cyclocondensation reactions with the participation of carboxylic acid imino esters are systematized in the review.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No.12, pp. 1587–1605, December 1992.