Jacek Mlochowski

Lithium diselenide in aprotic medium - a convenient reagent for synthesis of organic diselenides

Abstract The reduction of selenium with lithium in THF in the presence of diphenylacetylene as a catalyst afforded lithium diselenide, which reacted with electrophiles giving alkyl or aryl diselenides 1 - 3 and selenides 4 , as by-products. The useful method for preparation of diselenides based on this reaction was elaborated.

Selective oxidation of primary hydroxy groups in prinary-secondary diols

Abstract The two-phase oxidation of primary-secondary diols with sodium hypochlorite, mediated by TEMPO, brings about selective oxidation at the primary position. Such 5 diols are oxidized to the corresponding hydroxyaldehydes.

Benzeneperoxyseleninic acids-synthesis and properties

Abstract Benzeneperoxyseleninic acid ( 3 ) and its analogs, 2-nitro and 2,4-dinitrobenzeneperoxyseleninic acids ( 10 , 11 ), were obtained by oxidation of corresponding arylseleninic acids or diaryldiselenides with hydrogen peroxide. Their chemical properties were studied and rearrangement of 3 to benzeneselenic acid 7 was found as an useful method for preparation of this compound. In was also shown that peroxyseleninic acid 10 can be used as an efficient oxidant in the Baeyer-Villiger transformation of the formyl group into formyloxy one.

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.

Developments in Synthetic Application of Selenium(IV) Oxide and Organoselenium Compounds as Oxygen Donors and Oxygen-Transfer Agents

A variety of selenium compounds were proven to be useful reagents and catalysts for organic synthesis over the past several decades. The most interesting aspect, which emerged in recent years, concerns application of hydroperoxide/selenium(IV) oxide and hydroperoxide/organoselenium catalyst systems, as “green reagents” for the oxidation of different organic functional groups. The topic of oxidations catalyzed by organoselenium derivatives has rapidly expanded in the last fifteen years This paper is devoted to the synthetic applications of the oxidation reactions mediated by selenium compounds such as selenium(IV) oxide, areneseleninic acids, their anhydrides, selenides, diselenides, benzisoselenazol-3(2H)-ones and other less often used other organoselenium compounds. All these compounds have been successfully applied for various oxidations useful in practical organic syntheses such as epoxidation, 1,2-dihydroxylation, and α-oxyfunctionalization of alkenes, as well as for ring contraction of cycloalkanones, conversion of halomethyl, hydroxymethyl or active methylene groups into formyl groups, oxidation of carbonyl compounds into carboxylic acids and/or lactones, sulfides into sulfoxides, and secondary amines into nitrones and regeneration of parent carbonyl compounds from their azomethine derivatives. Other reactions such as dehydrogenation and aromatization, active carbon-carbon bond cleavage, oxidative amidation, bromolactonization and oxidation of bromide for subsequent reactions with alkenes are also successfully mediated by selenium (IV) oxide or organoselenium compounds. The oxidation mechanisms of ionic or free radical character depending on the substrate and oxidant are discussed. Coverage of the literature up to early 2015 is provided. Links have been made to reviews that summarize earlier literature and to the methods of preparation of organoselenium reagents and catalysts.

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.

Catalytic Oxidative Cyclocondensation of o‐Aminophenols to 2‐Amino‐3H‐phenoxazin‐3‐ones

Abstract The catalytic oxidative cyclocondensation of the o‐aminophenols 1a–f was investigated. The oxidants used were air/laccase, H2O2/horseradish peroxidase, H2O2/ebselen (3), and TBHP/diphenyl diselenide 4. The products obtained were 2‐amino‐3H‐phenoxazin‐3‐one—questiomycin A, its derivative 2b, and cinnabarinic acid and actinocin (2c,d). Substrates with methyl groups at 4 and 5 positions of benzene ring were converted to different dihydrophenoxazinones 2g,h. Compounds having chlorine atoms at the same positions underwent oxidation to planar phenoxa-zinones 2e,f with elimination of one hydrochloride molecule.

Benzisoselenazol-3(2H)-ones and bis(2-Carbamoyl)phenyl Diselenides as New Catalysts for Hydrogen Peroxide Oxidation of Organic Compounds

Abstract Bis (2-carbamoyl)phenyl diselenides and benzisoselenazol-3(2H)-ones, particularly ebselen, have been found as new catalysts for hydrogen peroxide oxidation of sulfides into sulfoxides, N,N-dimethylhydrazones into nitriles, and azines into carbonyl compounds.

The reactions of 2-(chloroseleno)benzoyl chloride with nucleophiles

Abstract The reactions of 2-(chloroseleno)benzoyl chloride with N, O and S nucleophiles such as alkanols, aminoalkanols, phenols, thiols, aminothiols and thiophenols have been investigated. It was found that the most reactive was a primary amino group which simultaneously underwent selenenylation–acylation. Less reactive hydroxy and thiol groups were selenenylated and/or acylated depending on the structure of the substrate and reaction conditions.

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.