The stobbe condensation with substituted succinic esters. II A synthesis of benzothiophene derivatives

The condensation of some thienyl carbonyl compounds with dimethyl phenylsuccinate using either sodium hydride or potassium t-butoxide as condensing agents, gave a stereoisomeric mixture of (E)- and (Z)-half-esters (3). The (E)-half-esters la-c were either cyclised to the corresponding benzothiophene derivatives or hydrolysed to the (E)-dibasic acids VIa-e, which were cyclised to the corresponding anhydrides VIIa-c. Methylation of VIIa,c gave the isomeric half-esters VIIIa,c. The (Z)-half-ester Id can cyclise easily to the lactone IX.     

Synthese de dienes gem-diactives : Selon une condensation apparentee a la reaction de stobbe

Condensation of carbonyl compounds with alkylidene cyanacetic esters using an equivalent of base, affords a new route to gem-diactivated dienes or trienes. The synthetic utility of the reaction is discussed with respect to the structure of the reactants. Configurations are determined by NMR after photoisomerisation experiments. Isolation of some δ-lactones, intermediates of the reaction, allows an interpretation of the mechanism and stereospecificity.     

Synthetic approaches to cularines. II. Ullmann condensation

The first total syntheses of O-methylcularicine 9b and sarcocapnine 9c are described together with a new synthesis of cularine 9a using the Ullmann condensation reaction of the appropriate 2′-bromo-8-hydroxy-tetrahydrobenzylisoquinoline formed by phase-transfer alkylation of Reissert compound 2. When this strategy was combined with the lead tetraacetate treatment of the tetrahydrobenzylisoquinoline it yielded 4-hydroxycularines, from which highly oxidized members of the family can be obtained. This is exemplified by the first synthesis of 4-hydroxysarcocapnine 19 and its transformation to the 3,4-dioxoisocularine yagonine 20 , rearrangement of which afforded the aristoisocularine aristoyagonine 21.     

Reaction of dicarbonyl compounds with dimethyl 3-ketoglutarate. Influence of steric effects on success of the condensation

The influence of steric factors on the synthesis of substituted bicyclo[3.3.0]octane-3,7 diones $\text{via}$ the condensation of 1,2-dicarbonyl compounds with dimethyl 3-ketoglutarate $\text{2}$ is described.     

Microwave assisted condensation reactions of 2-aryl hydrazonopropanals with nucleophilic reagents and dimethyl acetylenedicarboxylate

The reaction of methyl ketones 1a-g with dimethylformamide dimethylacetal (DMFDMA) afforded the enaminones 2a-g, which were coupled with diazotized aromatic amines 3a,b to give the corresponding aryl hydrazones 6a-h. Condensation of compounds 6a-h with some aromatic heterocyclic amines afforded iminoarylhydrazones 9a-m. Enaminoazo compounds 12a,b could be obtained from condensation of 6c with secondary amines. The reaction of 6e,h with benzotriazolylacetone yielded 14a,b. Also, the reaction of 6a,b,d-f,h with glycine and hippuric acid in acetic anhydride afforded pyridazinone derivatives 17a-f. Synthesis of pyridazine carboxylic acid derivatives 22a,b from the reaction of 6b,e with dimethyl acetylenedicarboxylate (DMAD) in the presence of triphenylphosphine at room temperature is also reported. Most of these reactions were conducted under irradiation in a microwave oven in the absence of solvent in an attempt to improve the product yields and to reduce the reaction times.     

Lewis acid catalyzed condensation of 2-aminohetarene N-oxides with N,N-dimethylformamide dimethyl acetal

Chemistry of Heterocyclic Compounds - A method for the introduction of the N,N-dimethylformamidine protective group in a series of six-membered 2-aminohetarene N-oxides was developed. It was shown...     

2-Methylpyridinium salts as 1,4-dinucleophiles. II. Westphal condensation with substituted pyridinium substrates

Condensation of α-methylpyridinium, quinolinium and isoquinolinium salts with 1,2-dicarbonyls in the presence of base, yielded quinolizinium derivatives. In an analogous process, α-benzyl derivatives produced 2,3-dihydroindolizin-2-ones by intramolecular cyclisation.     

Dialkylimidazolium dimethyl phosphates as solvents and catalysts for the Knoevenagel condensation reaction

The reaction between benzaldehyde and ethyl cyanoacetate is investigated in 1,3-dialkylimidazolium salts as solvents. The impact of both ions in these ionic liquids on the yield of the condensation reaction product is examined. Potentiometric titrations are employed for quantitative analyses of the best ionic liquids, revealing these to be 1,3-dialkylimidazolium dimethyl phosphates.     

Exactly alternating silarylene–siloxane polymers. II. The condensation polymerization of arylenedisilanols and bisureidosilanes

A new method for the preparation of exactly alternating silarylene–siloxane polymers by the low temperature step-growth condensation polymerization reaction of arylenedisilanols and bisurei-dosilanes in chlorobenzene was investigated. To obtain high molecular weight products ¹H NMR spectroscopy and gel permeation chromatography were used to monitor the polymerization reaction. By using these procedures 12 different polymers were prepared from 1,4-bis(dimethylhydroxysilyl)-benzene, 4,4′-bis(dimethylhydroxysilyl)phenyl ether, bis(1,1-tetramethylene-3-phenylureido)-dimethylsilane, and bis(1,1-tetramethylene-3-phenylureido)-methylvinylsilane monomers. The polymers were obtained in high yields, purities, and molecular weights.     

Potential anticonvulsants. III. The condensation of isatin with cyclic ketones

Isatin has been condensed with a series of cyclic ketones to give 3-substituted-3-hydroxyoxindoles as potential anticonvulsant agents.     

Potential anticonvulsants. V. The condensation of isatins with C-acetyl heterocyclic compounds

A number of C-acetyl heterocyclic compounds were condensed with isatin and substituted isatins to give a series of 3-hydroxy-3-substituted oxindoles. The products from 2-acetylfuran and isatin, 2-acetylthiophene and isatin, and 2-acetylpyridine and 1-methylisatin were active at 100 mg/Kg in the maximal electroshock seizure test.     

An ytterbium(II) complex with dimethyl ester of oxydiacetic acid

An Yb(II) complex with dimethyl ester of oxydiacetic acid, [Yb(CH(3)OOCCH(2)OCH(2)COOCH(3))3](ClO4)2, has been obtained by electrochemical reduction and its crystal structure has been determined. The complex cations have the D3 (32) crystallographic symmetry. The compound shows a very broad absorption band, starting from 500 nm towards the UV region, and traces of luminescence with a maximum at 545 nm. The performed density functional theory (DFT) calculations have shown that the absorption band results from mixed f-d and charge transfer transitions, and the empty antibonding pi* orbitals of the ester groups quench the luminescence.