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Papers by Giuseppe Celentano
Beilstein journal of organic chemistry, 2016
Different deep eutectic solvent (DES) mixtures were studied as reaction media for the continuous ... more Different deep eutectic solvent (DES) mixtures were studied as reaction media for the continuous synthesis of enantiomerically enriched products by testing different experimental set-ups. L-Proline-catalysed cross-aldol reactions were efficiently performed in continuo, with high yield (99%), anti-stereoselectivity, and enantioselectivity (up to 97% ee). Moreover, using two different DES mixtures, the diastereoselectivity of the process could be tuned, thereby leading to the formation, under different experimental conditions, to both the syn- and the anti-isomer with very high enantioselectivity. The excess of cyclohexanone was recovered and reused, and the reaction could be run and the product isolated without the use of any organic solvent by a proper choice of DES components. The dramatic influence of the reaction media on the reaction rate and stereoselectivity of the process suggests that the intimate architecture of DESs deeply influences the reactivity of different species inv...
Organic & biomolecular chemistry, Jan 17, 2015
An efficient organocatalytic methodology has been developed to perform the stereoselective additi... more An efficient organocatalytic methodology has been developed to perform the stereoselective addition of 2-carboxythioesters-1,3-dithiane to nitroalkenes. Under mild reaction conditions γ-nitro-β-aryl-α-keto esters with up to 92% ee were obtained, realizing a formal catalytic stereoselective conjugate addition of the glyoxylate anion synthon. The reaction products are versatile starting materials for further synthetic transformations; for example, the simultaneous reduction of the nitro group and removal of the dithiane ring was accomplished, allowing the preparation of a GABAB receptor agonist baclofen.
ChemInform, 2012
The title non-enzymic protein catalyzes the addition of aromatic or aliphatic thiols to α,β-unsat... more The title non-enzymic protein catalyzes the addition of aromatic or aliphatic thiols to α,β-unsaturated ketones in a stereoselective fashion to give enantioenriched β-sulfanyl ketones.
Organic & Biomolecular Chemistry, 2009
Monotopic and ditopic tripodal benzene platforms featuring aromatic and perfluoroaromatic side-ar... more Monotopic and ditopic tripodal benzene platforms featuring aromatic and perfluoroaromatic side-arms have been synthesized, and their binding properties toward C(60)-fullerene have been investigated by HPLC examining retention times on a fullerene-modified silica stationary phase, using highly polar eluants (acetonitrile and acetonitrile/water). By comparison of structurally homogeneous sets of receptors, a clear trend could be found, pointing to an increased retention for ditopic derivatives, in which binding can occur on both sides of the benzene platform, over their monotopic counterparts. Among the latter, monotopic receptors containing H-substituted aromatic residues showed stronger retention than their perfluorinated analogues. This effect was ascribed to the greater availability of the pi-electrons in a H-substituted aromatic ring with respect to the corresponding F-substituted counterpart in participating in a pi-pi interaction with the electron-poor surface of fullerene. Several NMR experiments aimed to investigate binding interactions in solution, using the much less polar solvents required by the fullerene solubility (1,1,2,2-tetrachloroethane, chloroform, toluene, and CS(2)), did not provide any evidence of binding interactions. We concluded that pi-pi interactions between fullerene and the investigated flexible tripodal receptors cannot compete with solvation in poorly polar solvents, and that the binding interactions observed by HPLC were essentially forced by the strongly polar eluant employed for the HPLC analysis.
Please note that technical editing may introduce minor changes to the text and/or graphics, which... more Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal's standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains.
Tetrahedron: Asymmetry, 2011
A biomimetic, inexpensive, and simple method for the stereoselective thio-Michael addition of thi... more A biomimetic, inexpensive, and simple method for the stereoselective thio-Michael addition of thiols to chalcones has been developed using bovine serum albumin (BSA) as a catalyst. Optically active products are obtained in high yield and with enantiomeric excesses of up to 70%.
ChemInform
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more 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.
ChemInform
Propargylic 1,2-anti-diol derivatives 2 and 10 are prepared in high yield and excellent diastereo... more Propargylic 1,2-anti-diol derivatives 2 and 10 are prepared in high yield and excellent diastereoselectivity by addition of r-alkoxypropargylstannanes 4a and 4b to aldehydes in the presence of BuSnCl 3 . We also introduce the use of KF on Celite as a convenient and mild reagent for removal of the organotin waste products of these reactions. 10.
Asian Journal of Organic Chemistry, 2014
ABSTRACT Organocatalytic stereoselective additions of different nucleophiles to β-nitroacrylates ... more ABSTRACT Organocatalytic stereoselective additions of different nucleophiles to β-nitroacrylates have been investigated. A thiourea-based cinchona-derived bifunctional catalyst promotes the addition of 1,3-diketones to differently substituted nitroacrylates in modest to fair yields and up to 93 % enantioselectivity. The 1,3 dicarbonyl functionality of the addition products was then used to synthesize enantiomerically enriched 3,4,5-trialkyl substituted pyrazoles via reaction with hydrazine. The stereoselective addition of N-methylindole to nitroacrylate was also preliminarily studied; the Friedel–Crafts alkylation was successfully organocatalyzed in the presence of an acid additive in very good yields and up to 53 % enantioselectivity.
Recyclable Catalysis, 2012
Tetrahedron, 2011
A highly stereoselective direct aldol condensation of ketones to aromatic aldehydes was realized;... more A highly stereoselective direct aldol condensation of ketones to aromatic aldehydes was realized; the trichlorosilyl enolether generated in situ in the presence of tetrachlorosilane is activated by catalytic amounts of an enantiomerically pure biheteroaromatic phosphine oxide to react with aldehydes, coordinated as well as activated by the chiral cationic hypervalent silicon species. This Lewis acid-mediated Lewis base-catalyzed transformation allowed, starting from two carbonyl compounds, to directly synthesize b-hydroxy ketones generally with high anti stereoselectivity and up to 93% ee for the anti isomer.
Tetrahedron: Asymmetry, 2009
Herein we report a mild and efficient method to synthesize chiral 3-aminosubstituted isothiazole ... more Herein we report a mild and efficient method to synthesize chiral 3-aminosubstituted isothiazole sulfoxides taking advantage of (+)- and (−)-((8,8-dichlorocamphoryl)sulfonyl)oxaziridine under microwave irradiation. The determination of the absolute configuration of the chiral sulfoxide was achieved by theoretical calculation of the CD spectra. The reason for the observed stereoselectivity was enlightened by means of analysis of our data using DFT calculations.
Synthesis, 2006
Indole derivatives R 0140 2-Trifluoromethanesulfonyloxyindole-1-carboxylic Acid Ethyl Ester: A Pr... more Indole derivatives R 0140 2-Trifluoromethanesulfonyloxyindole-1-carboxylic Acid Ethyl Ester: A Practical Intermediate for the Synthesis of 2-Carbosubstituted Indoles. -The readily available indole-2-yl triflate (III) undergoes Pd-catalyzed C-C coupling reactions with a range of nucleophiles giving rise to 2-carbo-substituted indole derivatives (V), (VII) and (IX) in good to high yields. -(ROSSI*, E.; ABBIATI, G.; CANEVARI, V.; CELENTANO, G.; MAGRI, E.; Synthesis 2006, 2, 299-304; Ist. Chim. Org., Fac. Farm., Univ. Stud. Milano, I-20133 Milano, Italy; Eng.) -M. Paetzel 22-121
Beilstein journal of organic chemistry, 2016
Different deep eutectic solvent (DES) mixtures were studied as reaction media for the continuous ... more Different deep eutectic solvent (DES) mixtures were studied as reaction media for the continuous synthesis of enantiomerically enriched products by testing different experimental set-ups. L-Proline-catalysed cross-aldol reactions were efficiently performed in continuo, with high yield (99%), anti-stereoselectivity, and enantioselectivity (up to 97% ee). Moreover, using two different DES mixtures, the diastereoselectivity of the process could be tuned, thereby leading to the formation, under different experimental conditions, to both the syn- and the anti-isomer with very high enantioselectivity. The excess of cyclohexanone was recovered and reused, and the reaction could be run and the product isolated without the use of any organic solvent by a proper choice of DES components. The dramatic influence of the reaction media on the reaction rate and stereoselectivity of the process suggests that the intimate architecture of DESs deeply influences the reactivity of different species inv...
Organic & biomolecular chemistry, Jan 17, 2015
An efficient organocatalytic methodology has been developed to perform the stereoselective additi... more An efficient organocatalytic methodology has been developed to perform the stereoselective addition of 2-carboxythioesters-1,3-dithiane to nitroalkenes. Under mild reaction conditions γ-nitro-β-aryl-α-keto esters with up to 92% ee were obtained, realizing a formal catalytic stereoselective conjugate addition of the glyoxylate anion synthon. The reaction products are versatile starting materials for further synthetic transformations; for example, the simultaneous reduction of the nitro group and removal of the dithiane ring was accomplished, allowing the preparation of a GABAB receptor agonist baclofen.
ChemInform, 2012
The title non-enzymic protein catalyzes the addition of aromatic or aliphatic thiols to α,β-unsat... more The title non-enzymic protein catalyzes the addition of aromatic or aliphatic thiols to α,β-unsaturated ketones in a stereoselective fashion to give enantioenriched β-sulfanyl ketones.
Organic & Biomolecular Chemistry, 2009
Monotopic and ditopic tripodal benzene platforms featuring aromatic and perfluoroaromatic side-ar... more Monotopic and ditopic tripodal benzene platforms featuring aromatic and perfluoroaromatic side-arms have been synthesized, and their binding properties toward C(60)-fullerene have been investigated by HPLC examining retention times on a fullerene-modified silica stationary phase, using highly polar eluants (acetonitrile and acetonitrile/water). By comparison of structurally homogeneous sets of receptors, a clear trend could be found, pointing to an increased retention for ditopic derivatives, in which binding can occur on both sides of the benzene platform, over their monotopic counterparts. Among the latter, monotopic receptors containing H-substituted aromatic residues showed stronger retention than their perfluorinated analogues. This effect was ascribed to the greater availability of the pi-electrons in a H-substituted aromatic ring with respect to the corresponding F-substituted counterpart in participating in a pi-pi interaction with the electron-poor surface of fullerene. Several NMR experiments aimed to investigate binding interactions in solution, using the much less polar solvents required by the fullerene solubility (1,1,2,2-tetrachloroethane, chloroform, toluene, and CS(2)), did not provide any evidence of binding interactions. We concluded that pi-pi interactions between fullerene and the investigated flexible tripodal receptors cannot compete with solvation in poorly polar solvents, and that the binding interactions observed by HPLC were essentially forced by the strongly polar eluant employed for the HPLC analysis.
Please note that technical editing may introduce minor changes to the text and/or graphics, which... more Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal's standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains.
Tetrahedron: Asymmetry, 2011
A biomimetic, inexpensive, and simple method for the stereoselective thio-Michael addition of thi... more A biomimetic, inexpensive, and simple method for the stereoselective thio-Michael addition of thiols to chalcones has been developed using bovine serum albumin (BSA) as a catalyst. Optically active products are obtained in high yield and with enantiomeric excesses of up to 70%.
ChemInform
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more 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.
ChemInform
Propargylic 1,2-anti-diol derivatives 2 and 10 are prepared in high yield and excellent diastereo... more Propargylic 1,2-anti-diol derivatives 2 and 10 are prepared in high yield and excellent diastereoselectivity by addition of r-alkoxypropargylstannanes 4a and 4b to aldehydes in the presence of BuSnCl 3 . We also introduce the use of KF on Celite as a convenient and mild reagent for removal of the organotin waste products of these reactions. 10.
Asian Journal of Organic Chemistry, 2014
ABSTRACT Organocatalytic stereoselective additions of different nucleophiles to β-nitroacrylates ... more ABSTRACT Organocatalytic stereoselective additions of different nucleophiles to β-nitroacrylates have been investigated. A thiourea-based cinchona-derived bifunctional catalyst promotes the addition of 1,3-diketones to differently substituted nitroacrylates in modest to fair yields and up to 93 % enantioselectivity. The 1,3 dicarbonyl functionality of the addition products was then used to synthesize enantiomerically enriched 3,4,5-trialkyl substituted pyrazoles via reaction with hydrazine. The stereoselective addition of N-methylindole to nitroacrylate was also preliminarily studied; the Friedel–Crafts alkylation was successfully organocatalyzed in the presence of an acid additive in very good yields and up to 53 % enantioselectivity.
Recyclable Catalysis, 2012
Tetrahedron, 2011
A highly stereoselective direct aldol condensation of ketones to aromatic aldehydes was realized;... more A highly stereoselective direct aldol condensation of ketones to aromatic aldehydes was realized; the trichlorosilyl enolether generated in situ in the presence of tetrachlorosilane is activated by catalytic amounts of an enantiomerically pure biheteroaromatic phosphine oxide to react with aldehydes, coordinated as well as activated by the chiral cationic hypervalent silicon species. This Lewis acid-mediated Lewis base-catalyzed transformation allowed, starting from two carbonyl compounds, to directly synthesize b-hydroxy ketones generally with high anti stereoselectivity and up to 93% ee for the anti isomer.
Tetrahedron: Asymmetry, 2009
Herein we report a mild and efficient method to synthesize chiral 3-aminosubstituted isothiazole ... more Herein we report a mild and efficient method to synthesize chiral 3-aminosubstituted isothiazole sulfoxides taking advantage of (+)- and (−)-((8,8-dichlorocamphoryl)sulfonyl)oxaziridine under microwave irradiation. The determination of the absolute configuration of the chiral sulfoxide was achieved by theoretical calculation of the CD spectra. The reason for the observed stereoselectivity was enlightened by means of analysis of our data using DFT calculations.
Synthesis, 2006
Indole derivatives R 0140 2-Trifluoromethanesulfonyloxyindole-1-carboxylic Acid Ethyl Ester: A Pr... more Indole derivatives R 0140 2-Trifluoromethanesulfonyloxyindole-1-carboxylic Acid Ethyl Ester: A Practical Intermediate for the Synthesis of 2-Carbosubstituted Indoles. -The readily available indole-2-yl triflate (III) undergoes Pd-catalyzed C-C coupling reactions with a range of nucleophiles giving rise to 2-carbo-substituted indole derivatives (V), (VII) and (IX) in good to high yields. -(ROSSI*, E.; ABBIATI, G.; CANEVARI, V.; CELENTANO, G.; MAGRI, E.; Synthesis 2006, 2, 299-304; Ist. Chim. Org., Fac. Farm., Univ. Stud. Milano, I-20133 Milano, Italy; Eng.) -M. Paetzel 22-121