Neospiroenones. Synthesis of 10,11-dimethoxy-1,6,6-trimethyl-5,6,8,12b-tetrahydrobenzo[d,f]indol-4(3H)-one and 10,11-dimethoxy-6,6-dimethyl- 1,5,6,12b-tetrahydrobenzo[d,f]indol-2(8H)-one

The three-component condensation of isobutyraldehyde, 3,4-dimethoxyphenylacetonitrile, and p-methylanisole or anisole in the presence of concentrated sulfuric acid affords neospiroenone systems.     

Hydrodynamic and bulk properties of dextrans in liquid media

Bulk and viscous properties of solutions of dextrans of different molecular weights in formamide, water, and dimethyl sulfoxide were studied. The fractal dimension of the biopolymer was estimated from the hydrodynamic data.     

Synthesis and photochemical properties of 3,6-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-9<Emphasis Type="Italic">H</Emphasis>-carbazole derivatives

Method of synthesis has been developed for a series of 3,6-di-tert-butyl-9H-carbazole derivatives and their photochemical properties have been investigated. The dependence of the Steglich esterification reaction on the nature of the catalyst was studied. The synthesized compounds show fluorescent emission in the range 400–600 nm with a high quantum yield.     

Mutable Lewis and Brønsted acidity of aluminated SBA-15 as revealed by NMR of adsorbed pyridine-15N

(1)H and variable-temperature (15)N NMR techniques have been used to study the effect of the gradual alumination of SBA-15 on the structure and adsorption properties of this mesoporous material. The interpretation of experimental spectra suggests that aluminum chlorhydrol most effectively reacts with silica surfaces in the confinement of the cavities of rough mesopore walls, instead of forming a homogeneous aluminum film. This first leads to a gradual filling of the cavities and finally results in aluminum islands on the inner surfaces of mesopores. In the sample with a Si/Al atomic ratio of 4.1, up to half of the inner surface area of the mesopores is covered with aluminum. The alumination produces Br?nsted acid sites attributed to silanol groups interacting with aluminum but does not affect the proton-donating ability of isolated silanol groups. At high Si/Al ratios, the surface contains only one type of Lewis site attributed to tetracoordinated aluminum. At lower Si/Al ratios, Lewis acid sites with a lower electron-accepting ability appear, as attributed to pentacoordinated aluminum. The numerical values of the surface densities of all chemically active sites have been estimated after annealing at 420 and 700 K. We were surprised to observe that gaseous nitrogen can occupy Lewis acid sites and hinder the interaction of the aluminum with any other electron donor. As a result, aluminated surfaces saturated with nitrogen do not exhibit any Br?nsted or Lewis acidity. At room temperature, it takes days before pyridine replaces nitrogen at the Lewis acid sites.     

Synthesis of novel racemic 3,4-dihydroferroceno[c]pyridines via the Ritter reaction

A new approach for the synthesis of functionalized racemic 3,4-dihydroferroceno[c]pyridines via the Ritter reaction of 2-methyl-1-ferrocenylpropan-1-ol with nitriles in the presence of methansulfonic acid was developed. The scope and limitations of the reaction were evaluated. Selected racemic 3,4-dihydroferroceno[c]pyridines were successfully separated by preparative HPLC on a Chiralcel OD-H column. The absolute configuration of the enantiomers was determined by X-ray crystal structure analysis.