Synthesis and transformations of new dihydro-β-campholenolactone derivatives

The reaction of xenon difluoride with enamino lactone 3 furnished the new α-fluoro aldehyde 7, whereas reaction of 3 with anhydrous HF led to racemic dihydro-β-campholenolactone 6. Acid-catalysed rearrangement of α-ethylidenelactone 4 proceeded with retention of configuration to give β-campholenolactone 8. Nitrosation of the novel bicyclic enamino lactone 6 afforded the corresponding oxime 9, while acid-catalysed treatment with primary amines, 2-methyl-1H-indole, potassium cyanide and hydrazine hydrochloride, furnished the dimethylamine substitution products 11–13 and the ‘ring switched’ product 14. The structures were determined by 2D NMR techniques, NOESY spectroscopy and X-ray diffraction.     

Synthesis and specific features of mesomorphic behavior of new polysubstituted triphenylenes

Previously unknown 2,3,6,7,10,11-hexakis(dodecyloxy)triphenylene and -(tetradecyloxy)triphenylene were synthesized. The structures of the synthesized compounds were proved by elemental analysis and spectral methods. Polymesomorphism was found for the first time and studied for substances of the hexaalkoxytriphenylene homologic series, as well as liotropic mesomorphism in a series of organic solvents.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1676–1681, August, 2004.     

Synthesis of chromanyl and dihydrobenzofuranyl piperazines

The synthesis of a series of regioisomeric chromanyl and dihydrobenzofuranyl piperazines is described.     

Synthesis of regiospecifically polysubstituted pyridazinones

Desymmetrization of pyridazine-3,6-diones by the use of N-benzyl protective groups leads to useful starting materials for building polysubstituted pyridazine libraries in a regioselective manner.     

Synthesis and transformations of polysubstituted diastereomeric 5-oxomorpholin-2-carboxylic acids

A series of trans- and cis-3,4-disubstituted 5-oxomorpholine-2-carboxylic acids 5 were prepared by a cyclocondensation between diglycolic anhydride 3 and arylideneamines 4. Transformations of the carboxylic group leading to a peptide bond in the side chain to the morpholinone ring were effected. The relative configurations and the preferred conformations of the substituents at the morpholinone ring in some of the newly prepared derivatives were determined by means of ¹H NMR and X-ray analysis.     

Enantiomerically pure piperazines via NaBH4/I2 reduction of cyclic amides

Enantiomerically pure (3S,7R,8aS)-3-phenyloctahydropyrrolo[1,2-a]pyrazine-7-ol, (3S,7R,8aS)-3-methyl octahydropyrrolo[1,2-a]pyrazine-7-ol, (3S,7R,8aS)-3-isopropyloctahydropyrrolo[1,2-a]pyrazine-7-ol and (3S,7R,8aS)-3-isobutyloctahydropyrrolo[1,2-a]pyrazine-7-ol 16d were synthesized via preparation of the corresponding cyclic amides from enantiomerically pure l-proline and hydroxyproline derivatives followed by reduction using sodium borohydride-iodine.     

Synthesis of polysubstituted 4-fluoroquinolinones

[reaction: see text] A convenient one-pot synthesis of 4-fluoroquinolinones that are active against KDR kinase is described. The mechanism of the reaction is believed to involve the formation of a quinone methide intermediate.     

Synthesis of substituted salicylamines and dihydro-2H-1,3-benzoxazines

Phenols were converted to their magnesium salts with the MgCl₂-Et₃N base system and subsequently reacted with Eschenmoser's salt, affording N,N-dimethyl substituted benzylamines in high to excellent yields. A series of mono N-substituted benzylamines were prepared in one-pot syntheses by ortho-formylation of phenols to corresponding salicylaldehydes, which in turn reacted with amines to imines. The imines were subsequently reduced to mono N-substituted benzylamines. Some of these benzylamines were further converted, without work-up, to mono N-substituted dihydro-2H-1,3-benzoxazines.     

Synthesis of 2-substituted piperazines via direct α-lithiation

A novel efficient synthetic route towards the pharmaceutically relevant 2-substituted piperazine class is described. The key step involves α-lithiation of N-Boc piperazines, followed by reaction with several electrophiles. To obtain high yields, in some cases transmetallation to copper after the lithiation step is required.     

Base-controlled selective construction of polysubstituted dihydrofuran and furan derivatives through an I2-mediated cyclization

A base-controlled formal [3 + 2] cycloaddition of 1,3-dicarbonyl compounds to enones via an I₂-mediated cyclization was reported. Highly functionalized dihydrofurans and furans were selectively obtained under I₂/DMAP and I₂/DBU conditions in the cyclization step, respectively.     

2-取代-3,4-二氢-1-异喹啉酮的合成和舒张血管活性

以3-羟基-4-甲氧基苯甲酸甲酯等为原料, 通过烯丙基醚化、Claisen重排、氧化、与伯胺反应(生成Schiff碱)、还原、分子内酯的胺解六步反应合成了一系列2-取代-3,4-二氢-1-异喹啉酮类化合物. Schiff碱的制备、还原、酯的胺解三步在“一锅”内完成. 采用1H NMR, MS和元素分析对目标化合物的结构进行了表征. 离体动脉环张力实验证明此类化合物具有明显舒张血管的作用.     

Synthesis of 2,6-disubstituted piperazines by a diastereoselective palladium-catalyzed hydroamination reaction

A highly diastereoselective intramolecular hydroamination is the key step in a modular synthesis of 2,6-disubstituted piperazines. The requisite hydroamination substrates were prepared in excellent yields by nucleophilic displacement of cyclic sulfamidates derived from amino acids. A variety of alkyl and aryl substituents at the 2-position were tolerated. The stereochemistry of the piperazines was determined to be trans by X-ray crystallography, which also showed the preferred conformation of the 2,6-disubstituted piperazine to be a twist-boat due to A(1,3) strain.     

Synthesis of polysubstituted cis- and trans-2,5-dihydronicotinonitriles

A method for synthesis of cis- and trans- polysubstituted 2,5-dihydronicotinonitriles III from N,N-disubstituted arylacetamidines I and ylidenemalononitriles II at room temperature in THF is reported.     

Synthesis of polysubstituted olefins by Pd-catalyzed cross-coupling reaction of tosylhydrazones and aryl nonaflates

Aryl nonaflates are employed as electrophiles in the Pd-catalyzed cross-coupling with tosylhydrazones affording di-, tri-, and tetrasubstituted olefins. Fine tunning of the reaction conditions are required to accomplish the coupling successfully, including the addition of LiCl and the presence of small amounts of water. Under the optimized conditions, the reactions proceed with high yield and also high stereoselectivity depending on the nature of the coupling partners.     

Synthesis of α-aminoketones via selective reduction of acyl cyanides

Reduction of acyl cyanides with zinc in acetic acid in the presence of excess acetic anhydride leads to N-acetyl-α-aminoketones in good yields. An efficient three-step synthesis of 5-aminolevulinic acid by this method is described.     

Synthesis of dihydro-1,3-thiazine derivatives. III

2-Carbamoylimino- and 2-thiocarbamoylimino-4-oxo-3,4-dihydro-2H-benzo[e]-1,3-thiazine derivatives were obtained by condensation of thiosalicylic acid with 3-alkyl(aryl)-substituted cyanoureas and cyanothioureas. 2-Hydroxy-3-mercaptoquinoline-4-carboxylic acid reacts similarly.See [1] for communication II.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 644–646, May, 1973.     

Synthesis of dihydro-1,3-thiazine derivatives. II

1-Oxo-3-thioxo-5-hydroxy-2-acyl-2,3-dihydro-1H-1,3-thiazino[6,5-c]quinolines were obtained for the first time by condensation of 2-hydroxy-3-mercaptoquinoline-4-carboxylic acid with acyl isothiocyanates. Alkyl and acyl isothiocyanates react with 1-methyl-2-oxo-3-mercapto-1, 2-dihydroquinoline-4-carboxylic acid to give 1,5-dioxo-3-thioxo-2-alkyl (acyl)6-methyl-2, 3,5,6-tetrahydro-1H-1,3-thiazino [6,5-c] quinolines.See [1] for communication I.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 641–643, May, 1973.