Computerized data acquisition and processing for Shpol'skii high-resolution spectrofluorimetry

The program described provides simultaneously digital control of a high-resolution spectrofluorimeter, acquisition of analog signals and data storage, and contains graphics processing to visualize spectra. Automatic evaluation software, which evaluates peak heights and calculates concentrations is included. The program runs on an IBM PC-AT2 (or compatible) equipped with interface cards; it is composed of distinct modules which are obtained through a menu. The system has been applied to the determination of 13 polynuclear aromatic hydrocarbons (PAHs); it offers high selectivity, excellent detection limits, and rapidity of data acquisition. Results obtained for 9 PAHs in a standard urban dust (SRM-1649) were satisfactory.     

Kinetics of the reaction of malachite green and crystal violet with formally aprotic solvents

The stability of malachite green and crystal violet has been studied spectrophotometrically in 17 formally aprotic media. The cations of these compounds react with solvents that are Lewis bases; the pseudo-first order rate constant values (k') are dependent on Gutmann's donor numbers. The sensitivity of the two dyes to the solvent effect correlates with the net charge on their central carbon atoms.     

Asymmetric photocycloaddition between furan and optically active ketones

The photochemical reaction between 3β-acetoxyandrost-5-en-17-one4 or (–)-methone5 and furan was preceded by isomerization of the ketones to the corresponding γδ-unsaturated aldehydes which subsequently added to furan furnishing 6-substituted 2,7-dioxabicyclo-[3.2.0]hept-3-enes,8 and9. Under the same conditions 1,2:5,6-di-O-isopropylidene α-d-ribo-hexofuranos-3-ulose12 reacted with furan without any isomerization and afforded all four stereoisomeric bicyclic photoadducts14–17. The ratio of the products resulting from the approach of the furan molecule to12 from the less hindered and from the more hindered sides was 3:1. This pointed at the decisive role of steric factors in controlling the course of photochemical cycloaddition.     

Isomorphisms of function modules, and generalized approximation in modulus

For a function algebra we investigate relations between the following three topics: isomorphisms of singly generated -modules, Morita equivalence bimodules, and ``real harmonic functions' with respect to . We also consider certain groups which are naturally associated with a uniform algebra . We illustrate the notions considered with several examples.

     

Synthesis of polyhydroxylated aza-bicyclic compounds from sugar allyltins

Highly functionalized polyhydroxylated dienoaldehyde, readily obtained from allyltin and d-glucose, served as a convenient precursor for a variety of configurationally different aza-bicyclic polyols. Such derivatives were deprotected and the activity of these free compounds against glycosidases was also tested.     

Synthesis of higher carbon sugars from dihydroxyacetone and d-arabinose: an organocatalytic approach

The reaction of 2,3:4,5-diacetone-d-arabinose with protected dihydroxyacetone catalyzed by l-proline afforded two diastereoisomeric octoses in a 7:1 ratio in 75% yield. The anti (3S,4S) configuration at the newly created stereogenic centers was assigned to the main isomer on the basis of the X-ray analysis. The same reaction when catalyzed with unnatural d-proline provided the same products in a 1:20 ratio.     

Synthesis of highly oxygenated decalins from sugar allyltins: an access to sulfur and phosphorus derivatives

A sugar allyltin derivative (with the d-gluco-configuration) was converted into d-xylo-dienoaldehyde and then into several bicyclic highly oxygenated compounds. The proposed methodology allows for a convenient synthesis of such derivatives containing heteroatoms other than oxygen. Molecular docking studies employing AutoDock 4.2 and AutoDock Vina were conducted in order to evaluate their activity as glycosidase inhibitors.     

An approach to highly oxygenated monocyclic derivatives with large rings

Coupling of the d-glucose and d-xylose derivatives via a phosphonate methodology provided a C12 higher sugar enone, which was converted into the protected dodecitol with both terminal free OH groups. This compound was used as a starting material for the preparation of highly oxygenated macrocyclic derivatives.