Chemical transformations of tetracyclo[3.3.1.1<Superscript>3,7</Superscript>.0<Superscript>1,3</Superscript>]decane (1,3-dehydroadamantane): IV. Reaction of 1,3-dehydroadamantane with dicarboxylic acids esters

Adamantylation of esters of dicarboxylic acids with 1,3-dehydroadamantane under mild conditions afforded in high yields diesters of (adamantan-1-yl)-substituted unsymmetrical dicarboxylic acids.     

Chemical transformations of tetracyclo[3.3.1.1.<Superscript>3,7</Superscript>.0.<Superscript>1,3</Superscript>]decane (1,3-dehydroadamantane): I. Reaction of 1,3-dehydroadamantane with carboxylic acids esters

Adamantylation of carboxylic acids esters was performed with 1,3-dehydroadamantane for the first time. The reaction proceeds under mild conditions and can be used as a convenient single stage procedure for the synthesis of esters of branched carboxylic acids having an adamantyl group in the α-position to the carbonyl group.     

Synthesis and transformations of 1,3-dithiol-2-ylideneisopropylidene malonates

The reaction of 2-alkylthio-1,3-dithiolium salts with Meldrum's acid gave 1,3-dithiol-2-ylideneisopropylidene malonates, which were converted successively to monoethyl esters of 1,3-dithiol-2-ylidenemalonic acids and esters of 1,3-dithiol-2-ylideneacetic acid. 2-Methyl-1,3-dithiolium salts are formed when 1,3-dithiol-2-ylideneisopropylidene malonates are heated with acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1621–1624, December, 1988.     

Enantiospecific synthesis of 1,3-disubstituted allenes by palladium-catalyzed coupling of propargylic compounds with arylboronic acids

An enantiospecific coupling of propargylic esters and carbonates with arylboronic acids has been developed using a palladium catalyst. Optically active 1,3-disubstituted allenes were synthesized with high enantiomeric excesses by carrying out the reactions under basic aqueous conditions.     

Modified method for the synthesis of isomeric N-substituted (1<Emphasis Type="Italic">H</Emphasis>-pyrazolyl)propane-1,3-diones

The condensation reaction of isomeric N-substituted (1H-pyrazol-4-yl)ethanones with the ethyl esters of pyrazole carboxylic acids and fluoroacetic acids has been studied using NaH as the base. Under optimized conditions, it proved to be a convenient and preparative method for the synthesis of N-substituted (1H-pyrazolyl)propane-1,3-diones and (1H-pyrazolyl)-4-polyfluorobutane-1,3-diones.     

Gold(I)/Chiral N,N′‐Dioxide–Nickel(II) Relay Catalysis for Asymmetric Tandem Intermolecular Hydroalkoxylation/Claisen Rearrangement

A highly efficient asymmetric cascade reaction between alkynyl esters and allylic alcohols has been realized. Key to success was the combination of a hydroalkoxylation reaction catalyzed by a π‐acidic gold(I) complex with a Claisen rearrangement catalyzed by a chiral Lewis acidic N,N′‐dioxide–nickel(II) complex. A range of acyclic α‐allyl β‐keto esters were synthesized in high yields (up to 99 %) with good diastereoselectivities (up to 97:3) and excellent enantioselectivities (up to 99 % ee ) under mild reaction conditions. These products can be easily transformed into optically active β‐hydroxy esters, β‐hydroxy acids, or 1,3‐diols.     

Gold(I)/Chiral N,N′-Dioxide–Nickel(II) Relay Catalysis for Asymmetric Tandem Intermolecular Hydroalkoxylation/Claisen Rearrangement

A highly efficient asymmetric cascade reaction between alkynyl esters and allylic alcohols has been realized. Key to success was the combination of a hydroalkoxylation reaction catalyzed by a π-acidic gold(I) complex with a Claisen rearrangement catalyzed by a chiral Lewis acidic N,N′-dioxide–nickel(II) complex. A range of acyclic α-allyl β-keto esters were synthesized in high yields (up to 99 %) with good diastereoselectivities (up to 97:3) and excellent enantioselectivities (up to 99 % ee) under mild reaction conditions. These products can be easily transformed into optically active β-hydroxy esters, β-hydroxy acids, or 1,3-diols.     

New synthesis of 2-heteroarylperfluoropropionic acids derivatives by reaction of azine N-oxides with hexafluoropropene

Hexafluoropropene reacts with aromatic azine N-oxides under mild conditions to produce fluorides of 2-heteroarylperfluoropropionic acids. The reaction proceeds as 1,3-dipolar cycloaddition followed by spontaneous scission of the N--O bond in the isoxazolidine ring and elimination of HF. When the reaction is carried out in the presence of alcohols or N-alkyl anilines, the in situ formed acyl fluorides give the corresponding esters and amides. They can be also treated separately with nucleophiles to produce the respective acylation products, whereas their hydrolysis leads to unstable carboxylic acids that undergo spontaneous decarboxylation to 1-aryl-1,2,2,2-tetrafluoroethanes. This new reaction provides a simple and general method of synthesizing 2-heteroarylperfluoropropionic acid derivatives that were previously unknown and unavailable.     

Kinetic Resolution of Racemic Secondary Benzylic Alcohols by the Enantioselective Esterification Using Pyridine‐3‐carboxylic Anhydride (3‐PCA) with Chiral Acyl‐Transfer Catalysts

Pyridine‐3‐carboxylic anhydride (3‐PCA) was found to function as an efficient coupling reagent for the preparation of carboxylic esters from various carboxylic acids with alcohols under mild conditions by a simple experimental procedure. This novel condensation reagent 3‐PCA was applicable not only for the synthesis of achiral carboxylic esters catalyzed by 4‐(dimethylamino)pyridine (DMAP) but also for the production of chiral carboxylic esters by the combination of chiral nucleophilic catalyst, such as tetramisole (=2,3,5,6‐tetrahydro‐6‐phenylimidazo[2,1‐b][1,3]thiazole) derivatives. An efficient kinetic resolution of racemic benzylic alcohols with achiral carboxylic acids was achieved by using 3‐PCA in the presence of (R)‐benzotetramisole ((R)‐BTM), and a variety of optically active carboxylic esters were produced with high enantiomeric excesses by this new chiral induction system without using a tertiary amine.     

Vanillin Esters of Aliphatic Acids in the Synthesis of 4,7-Phenanthroline Derivatives

Condensation of vanillin esters of aliphatic acids with 6-aminoquinoline and cyclic c-diketones (1,3-cyclohexanedione and dimedone) afforded new 2-methoxy-4-(11-oxo-7,8,9,10,11,12-hexahydrobenzo[b][4,7]phenanthrolin-12-yl)phenyl esters of carboxylic acids.     

Synthesis and transformations of derivatives of 2-aryl-5-(3,5-dimethyl-1H-pyrazol-1-yl)-1,3-oxazole-4-carboxylic acid

On the basis of methyl esters of 2-aryl-5-hydrazino-1,3-oxazole-4-carboxylic acids the earlier unknown methyl esters of 2-aryl-5-(3,5-dimethyl-1H-pyrazol-1-yl)-1,3-oxazole-4-carboxylic acids as well as their functional derivatives were synthesized. The latter were used for further transformations, in particular, for introducing the residues of highly basic aliphatic amines into the 5 position of oxazole, and the oxazol-2-yl moiety into the 4 position of the oxazole ring.     

Analogs of 2-Arachidonoylglycerin containing the no-donor group

1,3-Dinitroglyceryl esters of fatty acids, analogs of endocannabinoid 2-arachidonoylglycerin, were synthesized. Various methods for esterifying fatty acids with glycerine dinitrate were developed.     

Synthesis of 11C labelled methyl esters: transesterification of enol esters versus BF3 catalysed esterification—a comparative study

C-11 labelled methyl esters have been synthesized via the transesterification of enol esters in the presence of C-11 methanol and 1,3 dichlorodibutylstannoxane as catalyst. This method leaves functional groups intact and allows access to a wider variety of C-11 labelled methyl esters compared to the BF₃ catalysed ester formation, which uses carboxylic acids and C-11 methanol as starting materials.     

Synthesis of banana-like 1,3-dihydroxybenzene and 2,7-dihydroxynaphthalene esters and luminescence of their terbium(III) complexes

New esters of 1,3-dihydroxybenzene and 2,7-dihydroxynaphthalene with 4-(4-alkoxybenzoyloxy)-2-(or 3-)methoxybenzoic acids were synthesized. The correlation between their structure and liquid crystal properties was examined, and the luminescence characteristics of terbium(III) complexes with these esters were studied.     

Binaphthol-derived bisphosphoric acids serve as efficient organocatalysts for highly enantioselective 1,3-dipolar cycloaddition of azomethine ylides to electron-deficient olefins

A variety of chiral bisphosphoric acids derived from binaphthols have been evaluated for enantioselective 1,3-dipolar cycloaddition reactions, revealing that the feature of the linker in the catalysts exerted great impact on the stereoselectivity. Among them, the oxygen-linked bisphosphoric acid 1a provided the highest level of stereoselectivity for the 1,3-dipolar cycloaddition reaction tolerating a wide range of substrates including azomethine ylides, generated in situ from a broad scope of aldehydes and α-amino esters, and various electron-deficient dipolarophiles such as maleates, fumarates, vinyl ketones, and esters. This reaction actually represents one of the most enantioselective catalytic approaches to access structurally diverse pyrrolidines with excellent optical purity. Theoretical calculations with DFT method on the formation of azomethine ylides and on the transition states of the 1,3-dipolar cycloaddition step showed that the dipole and dipolarophile were simultaneously activated by the bifunctional chiral bisphosphoric acids through the formation of hydrogen bonds. The effect of the bisphosphoric acids on reactivity and stereochemistry of the three-component 1,3-dipolar cycloaddition reaction was also theoretically rationalized. The bisphosphoric acid catalyst 1a may take on a half-moon shape with the two phosphoric acid groups forming two intramolecular hydrogen bonds. In the case of maleates, one phosphate acts as a base to activate the 1,3-dipole, and simultaneously, the two hydroxyl groups in the catalyst 1a may respectively form two hydrogen bonds with the two ester groups of maleate to make it more electronically deficient as a much stronger dipolarophile to participate in a concerted 1,3-dipolar cycloaddition with azomethine ylide. However, in the cases involving acrylate and fumarate dipolarophiles, only one hydroxyl group forms a hydrogen bond with the ester functional group to lower the LUMO of the C-C double bond and another one is remained to adjust the acidity and basicity of two phosphoric acids to activate the dipole and dipolarophile more effectively.     

Resistance of polyfluorinated complete esters of polyhydric alcohols to thermal oxidation: Comparison with nonfluorinated analogs

Complete esters of pentaerythritol, trimethylolpropane, and 2,2-dimethyl-1,3-propanediol with polyfluorinated carboxylic acids were prepared by esterification. As determined by differential thermal gravimetric analysis in air, the resistance of the esters to thermal oxidation decreases in going from pentaerythritol derivatives to those of trimethylolpropane and then to those of 2,2-dimethyl-1,3-propanediol. The compounds synthesized surpass their nonfluorinated analogs in the resistance to thermal oxidation.     

Electrophilic substitution reactions of esters of 4,5-substituted 1,3-dithiol-2-ylideneacetic and 1,3-dithiol-2-ylidenemalonic acids

The electrophilic substitution reactions (with halogens, POCl₃ + DMF, diazonium salts, iodoso compounds) of both esters of 4,5-substituted 1,3-dithiol-2-ylideneacetic acids and sodium salts of monoethyl esters of the corresponding malonic acids can be used for the synthesis of 2-methylene-1,3-dithiole derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 898–900, July, 1989.     

Quick regiospecific analysis of fatty acids in triacylglycerols with GC using 1,3-specific lipase in butanol

A new micro-procedure for the quick regiospecific analysis of triacylglycerols (TAG) with a 1,3-specific lipase, Lipozyme IM 20 (produced from strains of Muccor miehei) is described. After dissolution of triacylglycerols in butan-1-ol or butan-2-ol 250 mg of Lipozyme IM 20 were added and the whole mixture was agitated. This operation was repeated 5-10 times and the esterified fatty acids in the form of butyl esters (FABE) were dissolved in pentane and washed with water. The pentane layer was dried over sodium sulfate and the solvent was removed under vacuum to a constant weight. The residue was analysed using GC-MS. The same triacylglycerols were converted to fatty acid methyl esters (FAME). The FAME were analysed by gas chromatography (GC).     

Synthesis of optically active polynucleotide analogs with polytrimethylenimine backbones and thymine moieties

Polynucleotide analogs with polytrimethylenimine backbones and optically active 2-(thymin-1-yl)propionic acids as pendants were prepared. Linear polytrimethylenimines were obtained by ring-opening polymerization of 2-phenyl-5,6-dyhydro-4H-1,3-oxazine and subsequent hydrolysis of the resulting polymers. 2-(Thymin-1-yl)propionic acids were reacted with N-hydroxy succinimide to form active esters. Optical purities of active esters were determined by NMR with chiral chemical shift reagents. The polynucloetide analogs and related monomer and dimer model compounds were prepared by grafting reactions using active esters.     

A practical synthetic approach to chiral α-aryl substituted ethylphosphonates

A convenient general method is reported for the synthesis of α-aryl substituted ethylphosphonic acids and esters by hydrogenation of α-aryl substituted ethenylphosphonic acids and esters. Racemic α-arylethylphosphonic acids and esters were prepared in 70–88% yield under palladium-assisted transfer hydrogenation conditions using ammonium formate. Asymmetric hydrogenation of α-arylethenylphosphonic acids using chiral Ru(II) catalysts led to α-arylethylphosphonic acids with enantiomeric excesses up to 86%.