The reduction of 2-cyclopropylcarbonyl-, 2-(thiophen-2-yl)carbonyl-, and 2-arylcarbonylbenzonitriles with sodium tetrahydridoborate afforded 3-cyclopropyl-, 3-(2-thiophen-2-yl)-, and 3-arylphthalides, respectively, in high yields. Under analogous conditions, 3-cyanobenzophenones were converted to the corresponding 3-cyanobenzhydrols.
UV irradiation of mixed phosphonium–iodonium ylide in CH2Cl2 leads to formation of free radicals with lifetimes of a few minutes detected by EPR. In mixtures of ylides with acetylenes, the structure of radicals changes, and their concentration and stability increase. In the presence of acetylenes, the radicals contain ylide and acetylene residues, and their EPR spectra have hyperfine coupling constants typical for 31P nuclei in C-radicals and for 1H nuclei, depending on the acetylene structure. It has been demonstrated that the observed radical products are formed from short-lived primary radicals.
3,7-Ditosyl-1,5-diphenyl-3,7-diazabicyclo[3.3.1]nonane has been found to adopt a chair–chair conformation in the crystalline state in contrast to 3,7-ditosyl-1,5-diphenyl-3,7-diazabicyclo[3.3.1]nonan-9-one, which had been previously found to exist in a chair-boat conformation.
Установили, что 3,7-дитозил-1,5-дифенил-3,7-диазабицикло[3.3.1]нонан принимает в кристаллическом состоянии конформацию кресло-кресло в отличие от имеющего в положении 9 кетогруппу 3,7-дитозил-1,5-дифенил-3,7-диазабицикло[3.3.1]нонан-9-она, принимающего в кристалле конформацию кресло-ванна.
In the extension of the electrostatic approach developed in the previous paper on the basis of the available experimental and ab initio calculations data, the geometric structure of acyclic organic molecules containing one isolated chemical bond C=C, C=O, or C=N was analyzed. In agreement with conventional σ/π-representation for this type of bonds, the electrostatic model was suggested, comprising two kinds of local electron densities (LEDs) differing in topology and polarizability, which are in the close spin–spin interaction and show some asymmetry in behavior under the action of external perturbing electrostatic forces (ESFs). Based on the previously introduced concepts of LEDs, point positive charges (PPCs), directions of their most effective interaction (MEI) and using the procedure of fixed molecule (FM), the capabilities of the model were demonstrated on the examples of typical alkenes, carbonyl compounds, azomethines and oximes.
Data on synthesis, reactivity and bioactivity of N-hydroxy(tetrahydrofuran-2-yl)amines were discussed in the present review. General approaches to chiral N-glycosylhydroxylamines based on reactions of hydroxylamine with cyclic five-membered hemiacetals or dihydrofurans as well as reactions of tetrahydrofuran-containing nitrones with nucleophiles were systematized. The application of N-hydroxy(tetrahydrofuran-2-yl)amines in the synthesis of chiral heterocycles, aminophosphonic acids, N-hydroxypropargylamines, as well as natural compounds (for example, sieboldin A), pharmaceuticals (Zileuton) and their analogs was demonstrated. It was found that depending on substituents, N-hydroxy(tetrahydrofuran-2-yl)-amines can act as lipoxygenase inhibitors, and show antioxidant, antitumor, antibacterial, and other types of activities.
New tricarbocyanine dyes with phosphonate groups (2, 3) were synthesized and their binding constants to bovine serum albumin (BSA) were determined. The binding constants of the synthesized tricarbocyanines and cardiogreen (1) (K b ~ 105 M–1) are similar, indicating an insignificant contribution of the Coulomb interaction to the complex formation, which is determined by the polymethine chain interaction with BSA. The fluorescence lifetimes attest to the formation of two types of complexes: the lifetime of the dye complex with BSA with a major contribution (~80%) is 740–800 ps, and a lifetime of ~210 ps corresponds to the complex of dye aggregates with BSA.
A reaction of octa-1,7and deca-1,9-dienes with an excess of bromofluorocarbene proceeds predominantly with the formation of a monoadduct, whereas the bis-adduct can be prepared by repeated cyclopropanation. The [1+2] cycloaddition of dichlorocarbene to the monoadduct of bromofluorocarbene with deca-1,9-diene gave a new bis(cyclopropane) containing gem-dichloro- and gem-bromofluorocyclopropane fragments in one molecule. The bis-adducts obtained were subjected to the heterocyclization with nitronium triflate: in the case of bis(gem-bromofluorocyclopropane) the reaction proceeded with retention of one dihalocyclopropane fragment and gave mononuclear pyrimidine N-oxide.
An ability of n-alkyl and 1-adamantylmethyl perchlorates to be converted to the corresponding N-alkylacetamides upon treatment with acetonitrile was demonstrated. This reaction is an example of Ritter-type reaction, which proceeds under exclusively mild conditions and requires no catalysis or special activation of reagents. N-Alkylacetamides were formed in quantitative yields in analytically pure form.