Biomedical subjects

A A Gakh

Publications and source records attributed to A A Gakh.

4 recordsLinked to original sources

PubMed2000

Synthetic utilization of polynitroaromatic compounds. 1. S-derivatization of 1-substituted 2,4,6-trinitrobenzenes with thiols.

Reactions of 1-R-2,4,6-trinitrobenenes (R = alkyl, protected aldehyde, aminocarbonyl, cyano groups, or isoxazole ring) with thiol salts were investigated. In most cases, these reactions gave a mixture of minor para and major ortho substitution products. Reactions of N,N-disubstituted 2,4,6-trinitrobenzamides with S-,O-, and N-nucleophiles afforded products of substitution of the p-nitro group exclusively. 1-Cyano-2,4,6-trinitrobenzene was found to be the most reactive and the least selective: all three nitro groups can be substituted using an excess of thiol salts. 2-R-4, 6-dinitrobenzamides showed no regioselectivity under similar conditions to yield 1:1 mixtures of para and ortho isomers.

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PubMed2000

Synthetic utilization of polynitroaromatic compounds. 2. Synthesis Of 4,6-dinitro-1,2-benzisothiazol-3-ones and 4,6-dinitro-1, 2-benzisothiazoles from 2-benzylthio-4,6-dinitrobenzamides.

Cyclization of 2-benzylthio-4,6-dinitrobenzamides to 4,6-dinitro-1, 2-benzisothiazol-3-ones was achieved using SO(2)Cl(2) in CH(2)Cl(2) at room temperature. Alkylation of these heterocycles proceeded in a nonregioselective manner to yield a mixture of corresponding O- and N-alkylated products. Oxidation of 4,6-dinitro-1,2-benzisothiazoles (50% H(2)O(2) in AcOH) afforded the corresponding S-oxides and S, S-dioxides, depending on oxidation conditions. Unexpectedly, oxidation of a 3-methoxy derivative resulted in ring opening with the formation of the corresponding sulfamide. Chlorination of these 4,6-dinitro-1,2-benzisothiazol-3-ones (PCl(5)-POCl(3)) gave the expected 3-chloroisothiazoles.

Journal Article↗

PubMedDate not supplied

Preparation of trifluoromethylpyridine libraries.

S-Alkylation followed by heterocyclization of trifluoromethyl-3-cyano-2(1H)-pyridinethiones was used for preparation of libraries of S-alkyl trifluoromethylpyridines and thieno[2,3-b]pyridines. The S-alkylation (in water--DMF mixtures) was successful for all 18 alkylating agents employed (yields typically > 50%). S-Alkyl derivatives were further converted to corresponding thieno[2,3-b]pyridines via heterocyclization in base conditions (yields > 65%). Structures of new compounds were elucidated by a combination of IR and 1H NMR spectroscopy and elemental analysis and were confirmed by means of single-crystal X-ray diffraction analysis.

Dihydropyridines↗

PubMedDate not supplied

Modular Chemical Descriptor Language (MCDL): composition, connectivity, and supplementary modules.

The Modular Chemical Descriptor Language (MCDL) was developed to address the need for linear representation of structural and other chemical information for chemical databases, E-journals, and the Internet. The current paper describes in detail two major modules of the language: the composition and connectivity modules, which provide a representation of chemical structure. These modules are created using simple hierarchical principles based on ASCII codes and are unique except for stereoisomers and a few special cases (e.g., valence isomers, knot-type compounds). The MCDL also provides for additional information (such as atom coordinates, bond orders, spectra, and physical-chemical characteristics) to be included as a set of supplementary modules.

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