Claudio Santi | University of Perugia (original) (raw)

Papers by Claudio Santi

Current Chemical Biology, 2013

Oxidative stress results from the formation of reactive oxygen species (ROS) such as peroxides th... more Oxidative stress results from the formation of reactive oxygen species (ROS) such as peroxides that cause damage to cell membranes and react with various biomolecules in mammalian cells. The selenoenzyme glutathione peroxidase (GPx) destroys peroxides by catalyzing their reduction to alcohols or water with the stoichiometric reductant glutathione. The effects of oxidative stress have been implicated in a variety of degenerative processes and disease states and for these reasons, there is considerable interest in the discovery of small molecule compounds that could reproduce a GPx-like activity. A review on the most recent acquisition in this area is here reported.

Synthetic Communications, 1997

Abstract: Abstract. Oxazolines or oxazolidin-2-ones are produced from the reaction of diphenyl di... more Abstract: Abstract. Oxazolines or oxazolidin-2-ones are produced from the reaction of diphenyl diselenide, ammonium persulfate and trifluoromethanesulfonic acid with alkenes in the presence of MeCN/H2O, NH2CN/H2O or NH2CO2Et.

Tetrahedron Letters, 2000

The synthesis of a new chiral non-racemic sulfur containing diselenide is described. The electrop... more The synthesis of a new chiral non-racemic sulfur containing diselenide is described. The electrophilic selenium reagent, produced from this diselenide by treatment with bromine and silver triflate, has been used to effect the selenomethoxylation and the selenohydroxylation of alkenes. These addition reactions occurred with good chemical yield and with high diastereoselectivities.

Tetrahedron Letters, 1998

By reaction with ammonium persulfate the easily available diselenide derived from (1R)-10. The ee... more By reaction with ammonium persulfate the easily available diselenide derived from (1R)-10. The ee was determined by IH-NMR in the presence of (S)-(+)-2,2,2-trifluoro-l-(9-anthryl)ethanol. 11. Tiecco, M.; Testaferri, L.; Tingoli, M.; Bagnoli, L.; Santi, C. J. Chem. Soc., Chem. Commun. 1993, 637-639. 12. Further investigations on this selenenylation-elimination procedure, as well as on other asymmetric intermolecular and intramolecular addition reactions promoted by 2d, axe presently under way.

Phosphorus Sulfur and Silicon and The Related Elements, 2008

Here we report the first example in which the phenylseleno group is directly substituted by a hyd... more Here we report the first example in which the phenylseleno group is directly substituted by a hydroxy function. The reaction is promoted by the PhSeOSO3H generated “in situ” by oxidation of (PhSe)2 with (NH4)2S2O8 at reflux in a 3:1 mixture of MeCN-H2O. Interestingly the reaction can be performed in “one pot” using a catalytic amount of diselenide affording the corresponding

Synlett, 1993

© Georg Thieme Verlag, Rüdigerstr. 14, 70469 Stuttgart, Germany. All rights reserved. This journa... more © Georg Thieme Verlag, Rüdigerstr. 14, 70469 Stuttgart, Germany. All rights reserved. This journal, including all individual contributions and illustrations published therein, is legally protected by copyright for the duration of the copyright period. Any use, exploitation or ...

Tetrahedron-asymmetry, 2000

A simple synthesis of two new nitrogen containing diselenides, 7 and 8, is described. These compo... more A simple synthesis of two new nitrogen containing diselenides, 7 and 8, is described. These compounds were employed as starting materials to effect the asymmetric methoxyselenenylation, the hydroxyselenenylation as well as the cyclofunctionalization of olefins. Starting from 7 all these addition processes occurred with good facial selectivity. Poor results were however obtained with 8. One-pot selenenylation-elimination sequences using catalytic amounts of the diselenide 7 have also been investigated.

Advanced Synthesis & Catalysis, 2008

The first general and efficient diphenyl diselenide-catalyzed dihydroxylation of double bonds is ... more The first general and efficient diphenyl diselenide-catalyzed dihydroxylation of double bonds is presented. Hydrogen peroxide can be used as the oxidizing agent, affording generally good yields and high diasteroselectivity.

European Journal of Organic Chemistry, 1998

Abstract By reaction with ammonium persulfate the easily available diselenide derived from (1R)-(... more Abstract By reaction with ammonium persulfate the easily available diselenide derived from (1R)-(+)-camphor was converted into the camphorselenenyl sulfate. This chiral nonracemic electrophilic selenium reagent reacted with alkenes, at 40 C in acetonitrile in the presence ...

Tetrahedron-asymmetry, 2002

The mixtures of two enantiomerically pure diastereoisomeric amido selenides, obtained from the re... more The mixtures of two enantiomerically pure diastereoisomeric amido selenides, obtained from the reactions of alkenes with camphorselenyl sulfate in a mixture of water and a nitrile, were treated with Lawesson's reagent to afford a mixture of the two corresponding thioamido derivatives. The two diastereoisomeric thioamido selenides could be easily separated by flash chromatography. The thioamido selenides, after activation with PhSeCl, underwent deselenylation by a stereospecific intramolecular substitution. Thus both enantiomeric thiazolines could be obtained in enantiomerically pure form.

Tetrahedron, 1997

... 0.00 Pyrrolidinamine, Piperidinamine and Tetrahydropyridazine Derivatives from Selenium Promo... more ... 0.00 Pyrrolidinamine, Piperidinamine and Tetrahydropyridazine Derivatives from Selenium Promoted Cyclization of Alkenyl Phenylhydrazones Marcello Tiecco,* Lorenzo ... 7. Tiecco, M.; Testaferri, L.; Tingoli, M.; Bagnoli, L.; Marini, FJ Chem. ... 11. De Kimpe, N.; Boelens, MJ Chem. ...

Tetrahedron-asymmetry, 2007

... Marcello Tiecco Corresponding Author Contact Information , a , E-mail The Corresponding Autho... more ... Marcello Tiecco Corresponding Author Contact Information , a , E-mail The Corresponding Author , Lorenzo Testaferri a , Luana Bagnoli Corresponding Author Contact Information , a , Catalina Scarponi a , Andrea Temperini a , Francesca Marini a and Claudio Santi a. ...

Synlett, 2001

... Marcello Tiecco * , Lorenzo Testaferri, Andrea Temperini, Luana Bagnoli, Francesca Marini, Cl... more ... Marcello Tiecco * , Lorenzo Testaferri, Andrea Temperini, Luana Bagnoli, Francesca Marini, Claudio Santi. * Dipartimento di Chimica e Tecnologia del Farmaco, Sezione di Chimica Organica, Università di Perugia, I-06100 Perugia, Italy; Fax + 39(075)5 85 51 16; E-mail: tiecco ...

Angewandte Chemie-international Edition, 2003

Organic azides are versatile starting materials for the synthesis of a variety of nitrogen-contai... more Organic azides are versatile starting materials for the synthesis of a variety of nitrogen-containing compounds. The azido group can react with both nucleophilic and electrophilic reagents and can be used in 1,3-dipolar cycloaddition reactions. One of the most convenient ways to produce organic azides is the electrophilic addition to alkenes of an appropriate reagent, such as hydrazoic acid, mercuric azide, or iodine azide. Considerably improved results were obtained by using organoselenium reagents. The first example of the azidoselenenylation of alkenes was reported by Hassner and Amarasekara. The reaction was effected with PhSeCl and sodium azide in DMSO and proceeded through the formation of a cyclic seleniranium ion intermediate, which then underwent ring opening by nucleophilic attack of the azide anion. The addition products therefore resulted from a stereospecific trans addition. However, the reaction was not regiospecific. Similarly, the reaction of exocyclic alkenes with N-(phenylseleno)phthalimide and azidotrimethylsilane gave rise to a mixture of regioisomers. More recently we reported that the stereospecific azidoselenenylation of alkenes can be carried out more conveniently with phenylselenenyl triflate and sodium azide in acetonitrile. We have also reported the use of an azido radical to promote the azidoselenenylation of olefins. The reaction is, of course, not stereospecific in this case, and the anti-Markownikoff addition products are formed. We report the first example of a remarkable asymmetric electrophilic azidoselenenylation of olefins that occurs with a very high level of facial selectivity. This process is made possible by the use of chiral, nonracemic selenium reagents. During the last 10 years several research groups have developed simple and efficient procedures for the preparation of chiral, nonracemic diselenides. These compounds have been employed in various asymmetric reactions, mainly as precursors of electrophilic reagents, but also as catalysts or as a source of chiral selenium anions. A common characteristic of all chiral diselenides studied is the close proximity of a heteroatom (oxygen or nitrogen) that can interact with selenium. We recently described the synthesis of the sulfur-containing diselenides di-2-[(1S)-1-(methylthio)ethyl]phenyl diselenide (1) and di-2-methoxy-6-[(1S)-1-(methylthio)ethyl]phenyl diselenide (2). Electrophilic reagents derived from these diselenides were used to effect asymmetric hydroxyselenenylation, methoxyselenenylation, and cyclofunctionalization reactions, [14] which proceeded with very high facial selectivity under very mild experimental conditions. Preliminary experiments on asymmetric azidoselenenylation were carried out on styrene with the chiral diselenides 1-5. Upon treatment with bromine and silver triflate, 1-5 were converted into the corresponding electrophilic selenenyl triflate reagents 6-10. These reacted with styrene (11) in the presence of 1 equivalent of sodium azide to afford a mixture of the corresponding diastereomeric addition products 12-16 (Scheme 1).

European Journal of Organic Chemistry, 1999

Tetrahedron, 2000

The substitution reactions of thiophene and 2-methylthiophene with the electrophilic selenenylati... more The substitution reactions of thiophene and 2-methylthiophene with the electrophilic selenenylating agent produced from the 2, 2′-dithienyl diselenide by oxidation with iodobenzene diacetate involve only the α-positions and give rise to the formation of oligo ( ...

Tetrahedron-asymmetry, 1999

Synthetic Communications, 1998

Abstract. Simple alkenes react with PhSeOTf and NaN3 in MeCN to afford p-phenylseleno azides as t... more Abstract. Simple alkenes react with PhSeOTf and NaN3 in MeCN to afford p-phenylseleno azides as the result of a stereospecific fruns addition. The regioselectivity of the process is determined by the structllre of the alkene. ... We have recently reported that alkenes 1 easily react ...

Current Chemical Biology, 2013

Oxidative stress results from the formation of reactive oxygen species (ROS) such as peroxides th... more Oxidative stress results from the formation of reactive oxygen species (ROS) such as peroxides that cause damage to cell membranes and react with various biomolecules in mammalian cells. The selenoenzyme glutathione peroxidase (GPx) destroys peroxides by catalyzing their reduction to alcohols or water with the stoichiometric reductant glutathione. The effects of oxidative stress have been implicated in a variety of degenerative processes and disease states and for these reasons, there is considerable interest in the discovery of small molecule compounds that could reproduce a GPx-like activity. A review on the most recent acquisition in this area is here reported.

Synthetic Communications, 1997

Abstract: Abstract. Oxazolines or oxazolidin-2-ones are produced from the reaction of diphenyl di... more Abstract: Abstract. Oxazolines or oxazolidin-2-ones are produced from the reaction of diphenyl diselenide, ammonium persulfate and trifluoromethanesulfonic acid with alkenes in the presence of MeCN/H2O, NH2CN/H2O or NH2CO2Et.

Tetrahedron Letters, 2000

The synthesis of a new chiral non-racemic sulfur containing diselenide is described. The electrop... more The synthesis of a new chiral non-racemic sulfur containing diselenide is described. The electrophilic selenium reagent, produced from this diselenide by treatment with bromine and silver triflate, has been used to effect the selenomethoxylation and the selenohydroxylation of alkenes. These addition reactions occurred with good chemical yield and with high diastereoselectivities.

Tetrahedron Letters, 1998

By reaction with ammonium persulfate the easily available diselenide derived from (1R)-10. The ee... more By reaction with ammonium persulfate the easily available diselenide derived from (1R)-10. The ee was determined by IH-NMR in the presence of (S)-(+)-2,2,2-trifluoro-l-(9-anthryl)ethanol. 11. Tiecco, M.; Testaferri, L.; Tingoli, M.; Bagnoli, L.; Santi, C. J. Chem. Soc., Chem. Commun. 1993, 637-639. 12. Further investigations on this selenenylation-elimination procedure, as well as on other asymmetric intermolecular and intramolecular addition reactions promoted by 2d, axe presently under way.

Phosphorus Sulfur and Silicon and The Related Elements, 2008

Here we report the first example in which the phenylseleno group is directly substituted by a hyd... more Here we report the first example in which the phenylseleno group is directly substituted by a hydroxy function. The reaction is promoted by the PhSeOSO3H generated “in situ” by oxidation of (PhSe)2 with (NH4)2S2O8 at reflux in a 3:1 mixture of MeCN-H2O. Interestingly the reaction can be performed in “one pot” using a catalytic amount of diselenide affording the corresponding

Synlett, 1993

© Georg Thieme Verlag, Rüdigerstr. 14, 70469 Stuttgart, Germany. All rights reserved. This journa... more © Georg Thieme Verlag, Rüdigerstr. 14, 70469 Stuttgart, Germany. All rights reserved. This journal, including all individual contributions and illustrations published therein, is legally protected by copyright for the duration of the copyright period. Any use, exploitation or ...

Tetrahedron-asymmetry, 2000

A simple synthesis of two new nitrogen containing diselenides, 7 and 8, is described. These compo... more A simple synthesis of two new nitrogen containing diselenides, 7 and 8, is described. These compounds were employed as starting materials to effect the asymmetric methoxyselenenylation, the hydroxyselenenylation as well as the cyclofunctionalization of olefins. Starting from 7 all these addition processes occurred with good facial selectivity. Poor results were however obtained with 8. One-pot selenenylation-elimination sequences using catalytic amounts of the diselenide 7 have also been investigated.

Advanced Synthesis & Catalysis, 2008

The first general and efficient diphenyl diselenide-catalyzed dihydroxylation of double bonds is ... more The first general and efficient diphenyl diselenide-catalyzed dihydroxylation of double bonds is presented. Hydrogen peroxide can be used as the oxidizing agent, affording generally good yields and high diasteroselectivity.

European Journal of Organic Chemistry, 1998

Abstract By reaction with ammonium persulfate the easily available diselenide derived from (1R)-(... more Abstract By reaction with ammonium persulfate the easily available diselenide derived from (1R)-(+)-camphor was converted into the camphorselenenyl sulfate. This chiral nonracemic electrophilic selenium reagent reacted with alkenes, at 40 C in acetonitrile in the presence ...

Tetrahedron-asymmetry, 2002

The mixtures of two enantiomerically pure diastereoisomeric amido selenides, obtained from the re... more The mixtures of two enantiomerically pure diastereoisomeric amido selenides, obtained from the reactions of alkenes with camphorselenyl sulfate in a mixture of water and a nitrile, were treated with Lawesson's reagent to afford a mixture of the two corresponding thioamido derivatives. The two diastereoisomeric thioamido selenides could be easily separated by flash chromatography. The thioamido selenides, after activation with PhSeCl, underwent deselenylation by a stereospecific intramolecular substitution. Thus both enantiomeric thiazolines could be obtained in enantiomerically pure form.

Tetrahedron, 1997

... 0.00 Pyrrolidinamine, Piperidinamine and Tetrahydropyridazine Derivatives from Selenium Promo... more ... 0.00 Pyrrolidinamine, Piperidinamine and Tetrahydropyridazine Derivatives from Selenium Promoted Cyclization of Alkenyl Phenylhydrazones Marcello Tiecco,* Lorenzo ... 7. Tiecco, M.; Testaferri, L.; Tingoli, M.; Bagnoli, L.; Marini, FJ Chem. ... 11. De Kimpe, N.; Boelens, MJ Chem. ...

Tetrahedron-asymmetry, 2007

... Marcello Tiecco Corresponding Author Contact Information , a , E-mail The Corresponding Autho... more ... Marcello Tiecco Corresponding Author Contact Information , a , E-mail The Corresponding Author , Lorenzo Testaferri a , Luana Bagnoli Corresponding Author Contact Information , a , Catalina Scarponi a , Andrea Temperini a , Francesca Marini a and Claudio Santi a. ...

Synlett, 2001

... Marcello Tiecco * , Lorenzo Testaferri, Andrea Temperini, Luana Bagnoli, Francesca Marini, Cl... more ... Marcello Tiecco * , Lorenzo Testaferri, Andrea Temperini, Luana Bagnoli, Francesca Marini, Claudio Santi. * Dipartimento di Chimica e Tecnologia del Farmaco, Sezione di Chimica Organica, Università di Perugia, I-06100 Perugia, Italy; Fax + 39(075)5 85 51 16; E-mail: tiecco ...

Angewandte Chemie-international Edition, 2003

Organic azides are versatile starting materials for the synthesis of a variety of nitrogen-contai... more Organic azides are versatile starting materials for the synthesis of a variety of nitrogen-containing compounds. The azido group can react with both nucleophilic and electrophilic reagents and can be used in 1,3-dipolar cycloaddition reactions. One of the most convenient ways to produce organic azides is the electrophilic addition to alkenes of an appropriate reagent, such as hydrazoic acid, mercuric azide, or iodine azide. Considerably improved results were obtained by using organoselenium reagents. The first example of the azidoselenenylation of alkenes was reported by Hassner and Amarasekara. The reaction was effected with PhSeCl and sodium azide in DMSO and proceeded through the formation of a cyclic seleniranium ion intermediate, which then underwent ring opening by nucleophilic attack of the azide anion. The addition products therefore resulted from a stereospecific trans addition. However, the reaction was not regiospecific. Similarly, the reaction of exocyclic alkenes with N-(phenylseleno)phthalimide and azidotrimethylsilane gave rise to a mixture of regioisomers. More recently we reported that the stereospecific azidoselenenylation of alkenes can be carried out more conveniently with phenylselenenyl triflate and sodium azide in acetonitrile. We have also reported the use of an azido radical to promote the azidoselenenylation of olefins. The reaction is, of course, not stereospecific in this case, and the anti-Markownikoff addition products are formed. We report the first example of a remarkable asymmetric electrophilic azidoselenenylation of olefins that occurs with a very high level of facial selectivity. This process is made possible by the use of chiral, nonracemic selenium reagents. During the last 10 years several research groups have developed simple and efficient procedures for the preparation of chiral, nonracemic diselenides. These compounds have been employed in various asymmetric reactions, mainly as precursors of electrophilic reagents, but also as catalysts or as a source of chiral selenium anions. A common characteristic of all chiral diselenides studied is the close proximity of a heteroatom (oxygen or nitrogen) that can interact with selenium. We recently described the synthesis of the sulfur-containing diselenides di-2-[(1S)-1-(methylthio)ethyl]phenyl diselenide (1) and di-2-methoxy-6-[(1S)-1-(methylthio)ethyl]phenyl diselenide (2). Electrophilic reagents derived from these diselenides were used to effect asymmetric hydroxyselenenylation, methoxyselenenylation, and cyclofunctionalization reactions, [14] which proceeded with very high facial selectivity under very mild experimental conditions. Preliminary experiments on asymmetric azidoselenenylation were carried out on styrene with the chiral diselenides 1-5. Upon treatment with bromine and silver triflate, 1-5 were converted into the corresponding electrophilic selenenyl triflate reagents 6-10. These reacted with styrene (11) in the presence of 1 equivalent of sodium azide to afford a mixture of the corresponding diastereomeric addition products 12-16 (Scheme 1).

European Journal of Organic Chemistry, 1999

Tetrahedron, 2000

The substitution reactions of thiophene and 2-methylthiophene with the electrophilic selenenylati... more The substitution reactions of thiophene and 2-methylthiophene with the electrophilic selenenylating agent produced from the 2, 2′-dithienyl diselenide by oxidation with iodobenzene diacetate involve only the α-positions and give rise to the formation of oligo ( ...

Tetrahedron-asymmetry, 1999

Synthetic Communications, 1998

Abstract. Simple alkenes react with PhSeOTf and NaN3 in MeCN to afford p-phenylseleno azides as t... more Abstract. Simple alkenes react with PhSeOTf and NaN3 in MeCN to afford p-phenylseleno azides as the result of a stereospecific fruns addition. The regioselectivity of the process is determined by the structllre of the alkene. ... We have recently reported that alkenes 1 easily react ...