Journal of the Chemical Society, Perkin Transactions 2, 1993
... Soc., Perkin Trans. 2, 1993, 515-519. Photochemical reaction of arenecarbonitriles in the pre... more ... Soc., Perkin Trans. 2, 1993, 515-519. Photochemical reaction of arenecarbonitriles in the presence of alkylsilanes, silyl ethers and silyl amines. Mariella Mella, Nicola d'Alessandro, Mauro Freccero and Angelo Albini. ... 11, LYC Lee, X. Ci, C. Giannotti and DG Whitten, J. Am. Chem. ...
ABSTRACT The reaction of 1,4-dicyanonaphthalene (DCN) with ethylbenzene, propylbenzene, and α-met... more ABSTRACT The reaction of 1,4-dicyanonaphthalene (DCN) with ethylbenzene, propylbenzene, and α-methylbenzyltrimethylsilane has been investigated and compared with previous results obtained using other benzylic donors. The relative yield of the different types of reaction observed, (a) substitution of a cyano group to yield naphthalenes 2, (b) addition to yield the dihydronaphthalenes 3 and 4, and (c) addition with cyclization to yield the tetracyclic derivatives 5 as well as the diastereoisomeric distribution within each type of product, show that these reactions occur by different paths, all initiated by electron transfer, involving respectively cleavage of the free radical cation [for case (a)], detachment of a proton or a silyI cation and (probably concerted) addition to DCN˙–[for case (b)]. and proton transfer within the initial radical ion pair [for case (c)].
... Chimica Organica, Universita, V. Taramelli 10 I27100 Pavia, Italy (Received in UK 12 March 19... more ... Chimica Organica, Universita, V. Taramelli 10 I27100 Pavia, Italy (Received in UK 12 March 1991) Key Words: Photochemical electron transfer; Benryl ethers radical ... see Table i) was accomplished by NMR (in the presence of Eu(FOD)3 in the case of compounds 2b2'b, since ...
Journal of the Chemical Society, Perkin Transactions 1, 1995
... Annamaria Deagostino; Mariella Mella,b Cristina Prandi a and Paolo Venture110 *9a a Istituto ... more ... Annamaria Deagostino; Mariella Mella,b Cristina Prandi a and Paolo Venture110 *9a a Istituto di Chimica Organica dell'Universita, Via P. Giuria, 7-1 10125 Torino, Italy Dipartimento di Chimica Organica dell ... 10 C. Canepa, C. Prandi, L. Sacchi and P. VentureIlo, J. Chem. ...
Chemical communications (Cambridge, England), Jan 21, 2003
A novel access to a 2-norbornyl cation under mild, non acidic conditions is found in the addition... more A novel access to a 2-norbornyl cation under mild, non acidic conditions is found in the addition of photochemically generated 4-dimethylaminophenyl cation to 2-norbornene. Deprotonation to nortricyclene or nucleophile addition ensue depending on the solvent characteristics.
A method for radical addition to alkenes is reported which is based on the photosensitized oxidat... more A method for radical addition to alkenes is reported which is based on the photosensitized oxidation of a tetraalkylstannane by an excited acceptor (A*), fragmentation of the radical cation, and addition of the thus formed radical to an electron-withdrawing substituted alkene (acrylonitrile and dimethyl maleate). Aromatic nitriles and esters can be used as the electron acceptors, and they are chosen in such a way that their radical anion (A'-) reduces the adduct (and not the educt) radical. In this way the adduct radical is reduced and protonated to yield the end product, and the acceptor functions as a nonconsumed electron transfer sensitizer. In several cases the alkylation occurs more efficiently in the presence of a secondary donor (phenanthrene or biphenyl). However, when the acceptor is too easily reduced in the ground state (as with 1,2,4,5-benzenetetracarbonitrile), coupling of the adduct radical with A'-competes with its reduction.
Nitrile oxides are oxidized by tertiary amine N-oxides in different solvents at room temperature ... more Nitrile oxides are oxidized by tertiary amine N-oxides in different solvents at room temperature to afford in the presence of dienes nitrosocarbonyl adducts in fair yields. The mild conditions used in oxidizing a variety of nitrile oxides promise a wide application of this method in synthetic processes.
A Convenient Route to 1,4-Monoprotected Dialdehydes, 1,4-Ketoaldehydes, γ-Lactols and γ-Lactones ... more A Convenient Route to 1,4-Monoprotected Dialdehydes, 1,4-Ketoaldehydes, γ-Lactols and γ-Lactones Through Radical Alkylation of α,β-Unsaturated Aldehydes in Organic and Organic-Aqueous Media. -The synthesis of title monoprotected dialdehydes or ketoaldehydes [cf. (III), (VI)] is smoothly achieved by photoinduced radical addition of 1,3-dioxolane or its 2-substituted analogues, resp., to α,β-unsaturated aldehydes. A wide range of enals is applicable, but acrolein undergoes polymerization and a conjugated dienal is also not suitable for this reaction. Application of alcohols like (VII) as radical precursors in this radical addition towards enals results in formation of lactols like (X), which are readily oxidized to lactones [cf. (VIII), (IX)]. In this reaction, aromatic aldehydes are unreactive. All reactions can be carried out neat or in MeCN as solvent with benzophenone as photosensitizer, or in aqueous solution using a water-soluble photosensitizer. -(DONDI, D.; CAPRIOLI, I.; FAGNONI*, M.; MELLA, M.; ALBINI, A.; Tetrahedron 59 (2003) 7, 947-957; Dip. Chim. Org.,
The Photochemistry of Lomefloxacin. An Aromatic Carbene as the Key Intermediate in Photodecomposi... more The Photochemistry of Lomefloxacin. An Aromatic Carbene as the Key Intermediate in Photodecomposition.
1,2,4-Oxadiazole-4-oxides undergo clean thermal cleavage in refluxing chlorobenzene or xylene to ... more 1,2,4-Oxadiazole-4-oxides undergo clean thermal cleavage in refluxing chlorobenzene or xylene to nitriles and nitrosocarbonyl intermediates, which are either trapped with suitable olefins to afford ene adducts or dimerize and rearrange to anhydrides.
Radical alkylation of some ketene dithioacetal S,S-dioxides failed through the tin hydride promot... more Radical alkylation of some ketene dithioacetal S,S-dioxides failed through the tin hydride promoted chain process but was successfully performed through stoichiometric photochemical initiation, either by electron transfer or hydrogen abstraction. In the first case, alkyl radicals were produced from tetralkylstannanes (t-Bu-, i-Pr-, n-Bu-SnR(3)) via radical cation fragmentation, while in the second case these were produced from alkanes (cyclohexane, adamantane) by benzophenone triplet. When bulky radicals (t-Bu, adamantyl) were involved, the addition occurred with complete diastereoselectivity.
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
New types of lariat type crown ethers containing peptide sidearms were prepared by using a novel ... more New types of lariat type crown ethers containing peptide sidearms were prepared by using a novel strategy employing single electron transfer (SET)-induced photocyclization reactions of α-silylether terminated phthalimides. Reactions of chiral substrates in this series produced diastereomeric mixtures of crown ether products as a result of the formation of new stereogenic center generation in the photocyclization process.
Sc(OTf)3]. -The targeted 4,4-diaryl esters (III) are usually formed in good yields and with enant... more Sc(OTf)3]. -The targeted 4,4-diaryl esters (III) are usually formed in good yields and with enantioselectivities up to 98%. -(FAITA, G.; MELLA, M.; TOSCANINI, M.; DESIMONI*, G.; Tetrahedron 66 (2010) 16, 3024-3029,
In the cation formed by photoinduced C-F bond cleavage in fleroxacin, intramolecular reaction wit... more In the cation formed by photoinduced C-F bond cleavage in fleroxacin, intramolecular reaction with the N-ethyl chain is prevented by the electron-withdrawing effect of fluorine and intermolecular attack by nucleophiles is facilitated.
Journal of the Chemical Society, Perkin Transactions 2, 1993
... Soc., Perkin Trans. 2, 1993, 515-519. Photochemical reaction of arenecarbonitriles in the pre... more ... Soc., Perkin Trans. 2, 1993, 515-519. Photochemical reaction of arenecarbonitriles in the presence of alkylsilanes, silyl ethers and silyl amines. Mariella Mella, Nicola d'Alessandro, Mauro Freccero and Angelo Albini. ... 11, LYC Lee, X. Ci, C. Giannotti and DG Whitten, J. Am. Chem. ...
ABSTRACT The reaction of 1,4-dicyanonaphthalene (DCN) with ethylbenzene, propylbenzene, and α-met... more ABSTRACT The reaction of 1,4-dicyanonaphthalene (DCN) with ethylbenzene, propylbenzene, and α-methylbenzyltrimethylsilane has been investigated and compared with previous results obtained using other benzylic donors. The relative yield of the different types of reaction observed, (a) substitution of a cyano group to yield naphthalenes 2, (b) addition to yield the dihydronaphthalenes 3 and 4, and (c) addition with cyclization to yield the tetracyclic derivatives 5 as well as the diastereoisomeric distribution within each type of product, show that these reactions occur by different paths, all initiated by electron transfer, involving respectively cleavage of the free radical cation [for case (a)], detachment of a proton or a silyI cation and (probably concerted) addition to DCN˙–[for case (b)]. and proton transfer within the initial radical ion pair [for case (c)].
... Chimica Organica, Universita, V. Taramelli 10 I27100 Pavia, Italy (Received in UK 12 March 19... more ... Chimica Organica, Universita, V. Taramelli 10 I27100 Pavia, Italy (Received in UK 12 March 1991) Key Words: Photochemical electron transfer; Benryl ethers radical ... see Table i) was accomplished by NMR (in the presence of Eu(FOD)3 in the case of compounds 2b2'b, since ...
Journal of the Chemical Society, Perkin Transactions 1, 1995
... Annamaria Deagostino; Mariella Mella,b Cristina Prandi a and Paolo Venture110 *9a a Istituto ... more ... Annamaria Deagostino; Mariella Mella,b Cristina Prandi a and Paolo Venture110 *9a a Istituto di Chimica Organica dell'Universita, Via P. Giuria, 7-1 10125 Torino, Italy Dipartimento di Chimica Organica dell ... 10 C. Canepa, C. Prandi, L. Sacchi and P. VentureIlo, J. Chem. ...
Chemical communications (Cambridge, England), Jan 21, 2003
A novel access to a 2-norbornyl cation under mild, non acidic conditions is found in the addition... more A novel access to a 2-norbornyl cation under mild, non acidic conditions is found in the addition of photochemically generated 4-dimethylaminophenyl cation to 2-norbornene. Deprotonation to nortricyclene or nucleophile addition ensue depending on the solvent characteristics.
A method for radical addition to alkenes is reported which is based on the photosensitized oxidat... more A method for radical addition to alkenes is reported which is based on the photosensitized oxidation of a tetraalkylstannane by an excited acceptor (A*), fragmentation of the radical cation, and addition of the thus formed radical to an electron-withdrawing substituted alkene (acrylonitrile and dimethyl maleate). Aromatic nitriles and esters can be used as the electron acceptors, and they are chosen in such a way that their radical anion (A'-) reduces the adduct (and not the educt) radical. In this way the adduct radical is reduced and protonated to yield the end product, and the acceptor functions as a nonconsumed electron transfer sensitizer. In several cases the alkylation occurs more efficiently in the presence of a secondary donor (phenanthrene or biphenyl). However, when the acceptor is too easily reduced in the ground state (as with 1,2,4,5-benzenetetracarbonitrile), coupling of the adduct radical with A'-competes with its reduction.
Nitrile oxides are oxidized by tertiary amine N-oxides in different solvents at room temperature ... more Nitrile oxides are oxidized by tertiary amine N-oxides in different solvents at room temperature to afford in the presence of dienes nitrosocarbonyl adducts in fair yields. The mild conditions used in oxidizing a variety of nitrile oxides promise a wide application of this method in synthetic processes.
A Convenient Route to 1,4-Monoprotected Dialdehydes, 1,4-Ketoaldehydes, γ-Lactols and γ-Lactones ... more A Convenient Route to 1,4-Monoprotected Dialdehydes, 1,4-Ketoaldehydes, γ-Lactols and γ-Lactones Through Radical Alkylation of α,β-Unsaturated Aldehydes in Organic and Organic-Aqueous Media. -The synthesis of title monoprotected dialdehydes or ketoaldehydes [cf. (III), (VI)] is smoothly achieved by photoinduced radical addition of 1,3-dioxolane or its 2-substituted analogues, resp., to α,β-unsaturated aldehydes. A wide range of enals is applicable, but acrolein undergoes polymerization and a conjugated dienal is also not suitable for this reaction. Application of alcohols like (VII) as radical precursors in this radical addition towards enals results in formation of lactols like (X), which are readily oxidized to lactones [cf. (VIII), (IX)]. In this reaction, aromatic aldehydes are unreactive. All reactions can be carried out neat or in MeCN as solvent with benzophenone as photosensitizer, or in aqueous solution using a water-soluble photosensitizer. -(DONDI, D.; CAPRIOLI, I.; FAGNONI*, M.; MELLA, M.; ALBINI, A.; Tetrahedron 59 (2003) 7, 947-957; Dip. Chim. Org.,
The Photochemistry of Lomefloxacin. An Aromatic Carbene as the Key Intermediate in Photodecomposi... more The Photochemistry of Lomefloxacin. An Aromatic Carbene as the Key Intermediate in Photodecomposition.
1,2,4-Oxadiazole-4-oxides undergo clean thermal cleavage in refluxing chlorobenzene or xylene to ... more 1,2,4-Oxadiazole-4-oxides undergo clean thermal cleavage in refluxing chlorobenzene or xylene to nitriles and nitrosocarbonyl intermediates, which are either trapped with suitable olefins to afford ene adducts or dimerize and rearrange to anhydrides.
Radical alkylation of some ketene dithioacetal S,S-dioxides failed through the tin hydride promot... more Radical alkylation of some ketene dithioacetal S,S-dioxides failed through the tin hydride promoted chain process but was successfully performed through stoichiometric photochemical initiation, either by electron transfer or hydrogen abstraction. In the first case, alkyl radicals were produced from tetralkylstannanes (t-Bu-, i-Pr-, n-Bu-SnR(3)) via radical cation fragmentation, while in the second case these were produced from alkanes (cyclohexane, adamantane) by benzophenone triplet. When bulky radicals (t-Bu, adamantyl) were involved, the addition occurred with complete diastereoselectivity.
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
New types of lariat type crown ethers containing peptide sidearms were prepared by using a novel ... more New types of lariat type crown ethers containing peptide sidearms were prepared by using a novel strategy employing single electron transfer (SET)-induced photocyclization reactions of α-silylether terminated phthalimides. Reactions of chiral substrates in this series produced diastereomeric mixtures of crown ether products as a result of the formation of new stereogenic center generation in the photocyclization process.
Sc(OTf)3]. -The targeted 4,4-diaryl esters (III) are usually formed in good yields and with enant... more Sc(OTf)3]. -The targeted 4,4-diaryl esters (III) are usually formed in good yields and with enantioselectivities up to 98%. -(FAITA, G.; MELLA, M.; TOSCANINI, M.; DESIMONI*, G.; Tetrahedron 66 (2010) 16, 3024-3029,
In the cation formed by photoinduced C-F bond cleavage in fleroxacin, intramolecular reaction wit... more In the cation formed by photoinduced C-F bond cleavage in fleroxacin, intramolecular reaction with the N-ethyl chain is prevented by the electron-withdrawing effect of fluorine and intermolecular attack by nucleophiles is facilitated.
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