Krystian Kloc

Synthesis of oxiranylquinones as new potential bioreductive alkylating agents

Abstract 1,4-Benzoquinones and 1,4-naphthoquinones carrying oxiranyl substituents have been synthesized as potential bioreduetive alkylating agents. The method presented here involves the syntheses of 1,4-dimethoxybenzalkehydes or 1,4-dimethoxynaphthaldehydes, and conversion of the carbonyl groups into the oxiranyl function using trimethylsulfonium chloride in the presence of powdered sodium hydroxide 1,4-Dimethoxy-2-oxiranyl-benzenes and 1,4-dimethoxy-2-oxiranylnaphthalenes have been oxidized to quinones with silver(II) dipicolinate.

Selective oxidation of aromatic aldehydes to arenecarboxylic acids using ebselen-tert-butyl hydroperoxide catalytic system

Abstract It has been found that aromatic aldehydes with electron-withdrawing as well as electron-donating substituents are oxidized to arenecarboxylic acids using tert-butyl hydroperoxide in the presence of ebselen (2-phenylbenzisoselenazol-3(2H)-one) as a catalyst. The reaction is highly chemoselective and formation of phenols, being the products of competitive Baeyer–Villiger rearrangement, is marginal. It has been assumed that this rearrangement is inhibited by steric hindrance of the electron-deficient oxygen atom in the transient tetrahedral intermediate.

Selenium(IV) Oxide Catalyzed Oxidation of Aldehydes to Carboxylic Acids with Hydrogen Peroxide

Abstract A convenient method for oxidative transformation of aromatic, hetero-aromatic and aliphatic aldehydes into carboxylic acids is presented. It is based on the oxidation of aldehydes in THF using 30% hydrogen peroxide in the presence of 5 molar % of selenium(IV) oxide. The scope and limitation of the method are discussed.

Synthesis of 7-azabenzisoselenazol-3(2H)-ones: A new group of selenium containing antimicrobials

Abstract A convenient, general method for synthesis of various 2-substituted 7-azabenzisoselenazol-3(2H)-ones having pyridine ring condensed with selenazolone moiety is presented. It is based on the conversion of 2-chloronicotinic acid into 2-(chloroseleno)nicotinic acid chloride and its reaction with primary amines. The title compounds were found in the antimicrobial assay in vitro to be highly active against broad spectrum of bacteria and fungi.

Selenenylation–acylation of ketones with 2-chloroselenobenzoyl chloride. A novel route to benzo[b]selenophenes

It has been found that enolizable ketones and 1,3-diones react in neutral or basic medium with biselectro-philes such as 2-chloroselenobenzoyl chloride. The reaction takes place on the active α-methylene group. Selenenylation and subsequent acylation of the α-carbon atom take place and, depending on the ketone used, 3-hydroxybenzo[b]selenophenes or benzo[b]selenophen-3(2H)-ones are produced in moderate to high yields.

New heterocyclic selenenamides: 1,2,4-benzoselenadiazin-3(4H)-ones and 1,3,2-benzodiselenazoles

Abstract Two groups of selenium-containing heterocycles having new, unique 1,2,4-benzoselenadiazine and 1,3,2-diselenazole ring systems with an endocyclic selenenamide C–N moiety are presented. The first type was obtained by oxidative cyclization of 2,2′-diselenobis(phenylureas) and the second type by the reaction of 1,2-di(bromoseleno)benzene with primary amines.

Bis(2-Chlorosulfonylphenyl) Diselenide—the Substrate for Organoselenium Sulfonamides

Abstract: Synthesis of bis(2-chlorosulfonylphenyl) diselenide (11) from 2-amino-benzenesulfonic acid was elaborated. It was shown that (11) is a good starting material for synthesis of the organoselenium sulfonamides, such as bis(2-sulfamoylphenyl) diselenides (3) and benz-2,3-azaselenathiophene 1,1-dioxides (4), being potential immunostimulants and oxidation catalysts.

RECENT DEVELOPMENTS IN THE CHEMISTRY AND BIOLOGY OF DISELENIDES, BENZISOSELENAZOLONES AND SELENINIC ACIDS

Abstract Syntheses of various groups of organoselenium compounds such as aryl and heteroaryl diselenides (1), bis(2-carbamoyl)phenyl diselenides (2), 1,2-benzisoselenazol-3(2H)-ones (3), their 1-oxides (4) and seleninic acids (5) are reported. Some of them manifest potent biological activity as immuno-modulators (compounds 1-3) and cytostatics (compounds 5)

Reaction of Active Methylene Groups with 1,2‐Di(Bromoseleno)Benzene toward Benzo‐1,3(2H)‐Diselenoles

Abstract The 1,2‐di(bromoseleno)benzene has been found to be a bifunctional electrophile able to react with C‐H acids. The tandem diselenylation of the active methylene group in β‐diketones, β‐keto‐ and β‐cyanoesters, diethyl malonate, and malonitrile resulted in the ring closure on the carbon atom. Based on this reaction, 2,2‐disubstituted benzo‐1,3(2H)‐diselenoles, a new group of selenaheterocycles, were obtained in good yields.

A 13C, 15N and 77Se NMR Study of Some Diseleno Sulfonamides

13C, 15N and 77Se NMR data are reported for ten title compounds. Some linear correlations of selenium, nitrogen and carbon chemical shifts values are described. A number of one- and two- bond 77Se-13C coupling constants values are also given.