Jacek Ścianowski

Highly efficient synthesis and antioxidant capacity of N-substituted benzisoselenazol-3(2H)-ones

A new, general one step synthesis of N-substituted benzisoselenazol-3(2H)-ones based on the reaction of o-iodobenzamides with lithium diselenide, is described. A series of alkyl and aryl derivatives was obtained in high yields (up to 98%). Their GPx-like antioxidant activity, tested by NMR, showed a significantly higher activity than ebselen.

The Use of Sulfides Derived from Carane, P-Menthane, Pinane, and Bornane in the Synthesis of Optically Active Epoxides

Abstract Convenient routes for the synthesis of optically active methyl, phenyl, and dimonoterpenyl sulfides derived from carane, p-menthane, pinane, and bornane were developed. Methyl and dimonoterpenyl sulfides have been obtained by the reaction of the corresponding monoterpene thiolates with methyl iodide or monoterpene tosylates. The reactions of monoterpene tosylates with sodium benzenethiolate gave the corresponding phenyl monoterpenyl sulfides. These sulfides were used for the sulfur ylide-mediated reaction to yield epoxides. Good diastereoselectivities up to 99:1 and low to moderate enantioselectivities were observed for the enantioselective synthesis of chiral epoxides. GRAPHICAL ABSTRACT

New glutathione peroxidase mimetics-Insights into antioxidant and cytotoxic activity

A series of N-alkyl benzisoselenazol-3(2H)-ones has been obtained and transformed to corresponding diselenides by the reduction with sodium borohydride. Additionally, efficient methodology for the oxidative Se-N bond formation by potassium iodate has been presented, new conversion of diselenide to benzisoselenazolone was observed. The GPx-like activity of all synthetized derivatives has been evaluated by NMR. N-Allyl diselenide was up to five times better antioxidant than ebselen. Anticancer capacity towards MCF7 and DU145 cancer cells has been also tested. The highest antiproliferative activity was obtained for N-cyclohexyl benzisoselenazolone.

New diphenyl diselenides o-substituted by an O(S,Se)-caranyl skeleton – synthesis and application in asymmetric reactions

An efficient methodology for the synthesis of diphenyl diselenides o-substituted by O(S,Se)-caranyl moieties has been presented. 4-Caranyl and 4-isocaranyl groups have been connected to the phenyl ring by an oxygen, sulfur or selenium atom. The influence of the selenium–heteroatom interactions on the diastereoselectivity of the methoxyselenenylation of styrene has been evaluated. The best result was obtained for diselenide with an O-caranyl group substituted in the ortho-position. X-ray crystal structure of this compound was determined and the observed intramolecular interactions were discussed. Additionally diselenides bearing a sulfur atom were transformed to the corresponding methyl o-(S-caranyl) and o-(S-isocaranyl)-substituted phenyl selenides, and were tested as catalysts in the Tsuji–Trost allylic alkylation and Henry reaction.

Chirality transfer through sulfur or selenium to chiral propellers

The mechanism of chirality transfer from a chiral alkyl substituent to a trityl moiety through sulfur or selenium atoms is analysed and discussed on the basis of ECD measurements, DFT structure and ECD spectra calculations. It is shown that the presence of a chalcogen atom is manifested by elongation of the distance between the chiral and the trityl moieties as well as by the change of electronic properties of the trityl chromophore while maintaining its chiroptical response to the chirality of the molecule.

Syntheses of the Optically Active Terpene Hydroxyphenylselenides

The optically active hydroxyphenylselenides derived from the p-menthane, carane, and pinane systems have been obtained. Two methods of hydroxyphenylselenides synthesis have been compared. The first method is based on the reaction of alkenes with N-(phenylseleno)succinimide in the presence of water, and the second from epoxides as a result of the reaction with sodium benzeneselenolate. The influence of the substrate structures on the composition of the obtained products has been demonstrated.

Synthesis of Selenium Derivatives of 3-Hydroxy-2-substituted-2,3-dihydroisoindol-1-ones

Regiospecific transformation of 3-hydroxy-2-substituted-2,3-dihydroisoindol-1-ones into their aryl and alkyl 7-selenium derivatives, via metallation and subsequent reaction with diselenides, is described.

Chiral dialkyl ditellurides: Conformation of chiral chromophore by circular dichroism and DFT calculation

The twisted structure of ditellurides, in a similar way as in other dichalcogenes, leads to different absorption of circularly polarized light by quasi-enantiomeric chiral orbitals. Chiral optically active ditellurides are not common compounds and this phenomenon is not widely reported. As chiral ditellurides found an application in asymmetric synthesis, their molecular structure, understood as their conformation, became an important factor for understanding their reactivity. Until now there are few examples of chiral ditellurides known and their structure was not analyzed in details. This article presents the results of our most recent research on the structure of chiral ditellurides investigated by electronic circular spectroscopy (ECD) supported by quantum-chemical calculation. This enables us to suggest a relationship between chirality of alkyl substituent and chirality (conformation) of ditelluride.

Water-dependent synthesis of biologically active diaryl diselenides

A new one-step method for the synthesis of diaryl diselenides has been developed. The reaction of oiodobenzamides with dilithium diselenide can be controlled by the presence of water providing a simple and efficient protocol to obtain benzisoselenazolones or diaryl diselenides. A series of N-aryl ebselen derivatives and the corresponding diselenides was obtained. All synthesized compounds were tested in vitro as antioxidants and cytotoxic agents. N-(2,3,4-trimethoxyphenyl)benzisoselenazol-3(2H)-one was the best in vitro antioxidant and the corresponding diselenide the most potent cytotoxic agent against prostate cancer cell line DU145, being inactive towards healthy prostate cell line PNT1A.

Terpenyl tellurides—Synthesis and application in asymmetric epoxidation

GRAPHICAL ABSTRACT ABSTRACT This work presents a synthesis of new group of unsymmetrical chiral tellurides obtained in the reaction of sodium methanetellurolate or sodium benzenetellurolate with appropriate terpenyl tosylates from p-menthane, carane, and pinane systems. Additionally, symmetrical diterpenyl tellurides were prepared according to our recently published method using sodium telluride and terpenyl tosylates. Methyl terpenyl, phenyl terpenyl, and diterpenyl tellurides were successfully used in tellurium ylide-mediated asymmetric epoxidation reaction. The best result of asymmetric epoxidation was obtained for dicaranyl telluride (d.r. cis:trans 11:89, e.r. trans 84:16).