Dario Landini - Academia.edu (original) (raw)

Papers by Dario Landini

Research paper thumbnail of Regioselective Opening of α‐ and β‐Alkoxyepoxides with Trimethylaluminum

Angewandte Chemie International Edition in English, 1982

The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 161. DOI:10.1... more The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 161. DOI:10.1002/anie.198201610

Research paper thumbnail of Specific Solvation as a Tool for the N‐Chemoselective Arylsulfonylation of Tyrosine and (4‐Hydroxyphenyl)glycine Methyl Esters

European Journal of Organic Chemistry, 2003

The methyl esters of L‐tyrosine and D‐(4‐hydroxyphenyl)glycine were directly transformed into the... more The methyl esters of L‐tyrosine and D‐(4‐hydroxyphenyl)glycine were directly transformed into the corresponding 2‐arylsulfonamido esters with arylsulfonyl chlorides, without protecting the phenolic hydroxy group. The reaction is conducted in a THF/DMF (8:1) mixture as solvent, and using lyophilized solid sodium carbonate as base. The N‐arylsulfonylation takes place with good yields (62−85%) in a chemoselective fashion, without racemization of the stereogenic carbon centers. The DMF (2.6 mol/mol amino ester) specifically solvates the oxygen atom of the formed N,O‐dianion, reducing its nucleophilicity and dramatically increasing the chemoselectivity of the N‐substitution. In contrast, in the absence of a highly coordinating additive, the phenoxide anion competes unfavorably with the 2‐amino group for the nucleophilic attack, and the N,O‐disulfonyl esters are produced with relevant yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Research paper thumbnail of Reductive Dehalogenation of Α-Halo Ketones with Benzenethiol Catalyzed by Iron-Polyphthalocyanine

Research paper thumbnail of Homocoupling of Aryl Halides Using Catalytic System of Palladium and Phosphite

Chemistry Letters, 2007

The palladium-catalyzed homocoupling of aryl halides was carried out using phosphite ligands. The... more The palladium-catalyzed homocoupling of aryl halides was carried out using phosphite ligands. The optimized reaction conditions were Pd 2 (dba) 3 , phosphite 1, and NaOt-Bu in diglyme, and the desired homocoupling products were afforded in moderate to good yields.

Research paper thumbnail of Cyanuric chloride catalyzed Beckmann rearrangement of ketoximes in biodegradable ionic liquids

Tetrahedron, 2012

In order to find an efficient catalytic system for Beckmann rearrangement of ketoximes, cyanuric ... more In order to find an efficient catalytic system for Beckmann rearrangement of ketoximes, cyanuric chloride and Lewis acids were screened, and the cyanuric chloride /manganese chloride tetrahydrate system with good catalytic effect has been discovered. Using 2 mol% cyanuric chloride and 2 mol% MnCl 2 •4H 2 O as catalyst, the yield of Beckmann rearrangement of benzophenone oxime was 96% after refluxing for 2 h in acetonitrile. A variety of ketoximes underwent the Beckmann rearrangement to afford the corresponding amides in moderate to high yields.

Research paper thumbnail of Chemoselective N-alkylation of 2-hydroxycarbazole as a model for the synthesis of N-substituted pyrrole derivatives containing acidic functions

Tetrahedron, 1995

2-Hydroxycarbazole (1) was chemoselectively N-alkylated with several alkyl halides 3 by generatin... more 2-Hydroxycarbazole (1) was chemoselectively N-alkylated with several alkyl halides 3 by generating the corresponding N,O-dianion using excess sodium hydride in a suitable solvent, under anhydrous conditions. The highest yields (87-96%) of 9-alkyl-2-hydroxycarbazoles 4 and the mildest reaction conditions were reached in THF containing DMF as an additive (2 mol equiv), but other solvents (DMSO, diglyme, DME) or solvent-additive systems (THF-diglyme, THF-DMSO, DME-DMF, diglyme-DMF) are effective.

Research paper thumbnail of Synthesis of 2-amino acids via selective mono-N-alkylation of trichloroacetamide by 2-bromo carboxylic esters under solid-liquid phase-transfer catalysis conditions

The Journal of Organic Chemistry, 1992

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.

Research paper thumbnail of Straightforward Synthesis of 2-Substituted 3,4-Dihydro-2 H -1,4-benzoxazines under Solid−Liquid Phase Transfer Catalysis Conditions

Industrial & Engineering Chemistry Research, 2003

ABSTRACT A straightforward and efficient synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazin... more ABSTRACT A straightforward and efficient synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazines 6−9 has been carried out in excellent overall yields through the ring opening of epoxides 1 with arylsulfonamides 2 and 3, followed by cyclization of the hydroysulfonamides 4 and 5 thus obtained. Both steps are carried out under solid−liquid phase transfer catalysis (SL-PTC) conditions using potassium carbonate and sodium hydroxide as bases. The procedure is feasible for the synthesis of non-racemic 2-substituted benzoxazines.

Research paper thumbnail of Cyanuric chloride catalyzed Beckmann rearrangement of ketoximes in biodegradable ionic liquids

Tetrahedron, 2012

ABSTRACT Imidazolium-based ionic liquids (ILs) containing ester moieties in the side chain were s... more ABSTRACT Imidazolium-based ionic liquids (ILs) containing ester moieties in the side chain were successfully used as an alternative to traditional ILs in the Beckmann rearrangement of ketoximes catalyzed by 2,4,6-trichloro[1,3,5]triazine. The procedure is mild and suitable for both aromatic and cycloaliphatic substrates affording the rearrangement products in good to quantitative yields. The process is eco-sustainable since these ILs are biodegradable and in addition they can be recovered and reused.

Research paper thumbnail of Novel concise synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazines by ring opening of glycidols under solid-liquid phase transfer catalysis conditions†

Chemical Communications, 1999

ABSTRACT The ring opening of glycidols with N-(2-fluorophenyl)toluene-p-sulfonamide under SL-PTC ... more ABSTRACT The ring opening of glycidols with N-(2-fluorophenyl)toluene-p-sulfonamide under SL-PTC conditions, followed by ring closure with ButOK, provides a novel high yielding synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazines.

Research paper thumbnail of Key Role of Water for Nucleophilic Substitutions in Phase-Transfer-Catalyzed Processes:  A Mini-Review

Industrial & Engineering Chemistry Research, 2001

ABSTRACT The fundamental role of water in anion-promoted reactions carried out under both liquid−... more ABSTRACT The fundamental role of water in anion-promoted reactions carried out under both liquid−liquid and solid−liquid phase-transfer catalysis (LL- and SL-PTC, respectively) conditions is reviewed. In particular, the hydration effect on the quaternary onium salt extraction constants, anion selectivity coefficients, and anion reactivity under LL-PTC conditions is reported. The effect of added water on SL-PTC reaction rates is also included. In addition, guidelines for optimizing the amount of water in the application of PTC to organic synthesis are proposed.

Research paper thumbnail of ChemInform Abstract: Synthesis and Activity of Cephalosporins Containing an Oxyiminomethylene Functionality in the ortho-Position of a Phenyl or Phenoxyacetic Acid C-7 Side Chain Substituent

Research paper thumbnail of Regioselective Opening of α‐ and β‐Alkoxyepoxides with Trimethylaluminum

Angewandte Chemie International Edition in English, 1982

The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 161. DOI:10.1... more The complete manuscript of this communication appears in: Angew. Chem. Suppl. 1982, 161. DOI:10.1002/anie.198201610

Research paper thumbnail of Specific Solvation as a Tool for the N‐Chemoselective Arylsulfonylation of Tyrosine and (4‐Hydroxyphenyl)glycine Methyl Esters

European Journal of Organic Chemistry, 2003

The methyl esters of L‐tyrosine and D‐(4‐hydroxyphenyl)glycine were directly transformed into the... more The methyl esters of L‐tyrosine and D‐(4‐hydroxyphenyl)glycine were directly transformed into the corresponding 2‐arylsulfonamido esters with arylsulfonyl chlorides, without protecting the phenolic hydroxy group. The reaction is conducted in a THF/DMF (8:1) mixture as solvent, and using lyophilized solid sodium carbonate as base. The N‐arylsulfonylation takes place with good yields (62−85%) in a chemoselective fashion, without racemization of the stereogenic carbon centers. The DMF (2.6 mol/mol amino ester) specifically solvates the oxygen atom of the formed N,O‐dianion, reducing its nucleophilicity and dramatically increasing the chemoselectivity of the N‐substitution. In contrast, in the absence of a highly coordinating additive, the phenoxide anion competes unfavorably with the 2‐amino group for the nucleophilic attack, and the N,O‐disulfonyl esters are produced with relevant yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Research paper thumbnail of Reductive Dehalogenation of Α-Halo Ketones with Benzenethiol Catalyzed by Iron-Polyphthalocyanine

Research paper thumbnail of Homocoupling of Aryl Halides Using Catalytic System of Palladium and Phosphite

Chemistry Letters, 2007

The palladium-catalyzed homocoupling of aryl halides was carried out using phosphite ligands. The... more The palladium-catalyzed homocoupling of aryl halides was carried out using phosphite ligands. The optimized reaction conditions were Pd 2 (dba) 3 , phosphite 1, and NaOt-Bu in diglyme, and the desired homocoupling products were afforded in moderate to good yields.

Research paper thumbnail of Cyanuric chloride catalyzed Beckmann rearrangement of ketoximes in biodegradable ionic liquids

Tetrahedron, 2012

In order to find an efficient catalytic system for Beckmann rearrangement of ketoximes, cyanuric ... more In order to find an efficient catalytic system for Beckmann rearrangement of ketoximes, cyanuric chloride and Lewis acids were screened, and the cyanuric chloride /manganese chloride tetrahydrate system with good catalytic effect has been discovered. Using 2 mol% cyanuric chloride and 2 mol% MnCl 2 •4H 2 O as catalyst, the yield of Beckmann rearrangement of benzophenone oxime was 96% after refluxing for 2 h in acetonitrile. A variety of ketoximes underwent the Beckmann rearrangement to afford the corresponding amides in moderate to high yields.

Research paper thumbnail of Chemoselective N-alkylation of 2-hydroxycarbazole as a model for the synthesis of N-substituted pyrrole derivatives containing acidic functions

Tetrahedron, 1995

2-Hydroxycarbazole (1) was chemoselectively N-alkylated with several alkyl halides 3 by generatin... more 2-Hydroxycarbazole (1) was chemoselectively N-alkylated with several alkyl halides 3 by generating the corresponding N,O-dianion using excess sodium hydride in a suitable solvent, under anhydrous conditions. The highest yields (87-96%) of 9-alkyl-2-hydroxycarbazoles 4 and the mildest reaction conditions were reached in THF containing DMF as an additive (2 mol equiv), but other solvents (DMSO, diglyme, DME) or solvent-additive systems (THF-diglyme, THF-DMSO, DME-DMF, diglyme-DMF) are effective.

Research paper thumbnail of Synthesis of 2-amino acids via selective mono-N-alkylation of trichloroacetamide by 2-bromo carboxylic esters under solid-liquid phase-transfer catalysis conditions

The Journal of Organic Chemistry, 1992

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.

Research paper thumbnail of Straightforward Synthesis of 2-Substituted 3,4-Dihydro-2 H -1,4-benzoxazines under Solid−Liquid Phase Transfer Catalysis Conditions

Industrial & Engineering Chemistry Research, 2003

ABSTRACT A straightforward and efficient synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazin... more ABSTRACT A straightforward and efficient synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazines 6−9 has been carried out in excellent overall yields through the ring opening of epoxides 1 with arylsulfonamides 2 and 3, followed by cyclization of the hydroysulfonamides 4 and 5 thus obtained. Both steps are carried out under solid−liquid phase transfer catalysis (SL-PTC) conditions using potassium carbonate and sodium hydroxide as bases. The procedure is feasible for the synthesis of non-racemic 2-substituted benzoxazines.

Research paper thumbnail of Cyanuric chloride catalyzed Beckmann rearrangement of ketoximes in biodegradable ionic liquids

Tetrahedron, 2012

ABSTRACT Imidazolium-based ionic liquids (ILs) containing ester moieties in the side chain were s... more ABSTRACT Imidazolium-based ionic liquids (ILs) containing ester moieties in the side chain were successfully used as an alternative to traditional ILs in the Beckmann rearrangement of ketoximes catalyzed by 2,4,6-trichloro[1,3,5]triazine. The procedure is mild and suitable for both aromatic and cycloaliphatic substrates affording the rearrangement products in good to quantitative yields. The process is eco-sustainable since these ILs are biodegradable and in addition they can be recovered and reused.

Research paper thumbnail of Novel concise synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazines by ring opening of glycidols under solid-liquid phase transfer catalysis conditions†

Chemical Communications, 1999

ABSTRACT The ring opening of glycidols with N-(2-fluorophenyl)toluene-p-sulfonamide under SL-PTC ... more ABSTRACT The ring opening of glycidols with N-(2-fluorophenyl)toluene-p-sulfonamide under SL-PTC conditions, followed by ring closure with ButOK, provides a novel high yielding synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazines.

Research paper thumbnail of Key Role of Water for Nucleophilic Substitutions in Phase-Transfer-Catalyzed Processes:  A Mini-Review

Industrial & Engineering Chemistry Research, 2001

ABSTRACT The fundamental role of water in anion-promoted reactions carried out under both liquid−... more ABSTRACT The fundamental role of water in anion-promoted reactions carried out under both liquid−liquid and solid−liquid phase-transfer catalysis (LL- and SL-PTC, respectively) conditions is reviewed. In particular, the hydration effect on the quaternary onium salt extraction constants, anion selectivity coefficients, and anion reactivity under LL-PTC conditions is reported. The effect of added water on SL-PTC reaction rates is also included. In addition, guidelines for optimizing the amount of water in the application of PTC to organic synthesis are proposed.

Research paper thumbnail of ChemInform Abstract: Synthesis and Activity of Cephalosporins Containing an Oxyiminomethylene Functionality in the ortho-Position of a Phenyl or Phenoxyacetic Acid C-7 Side Chain Substituent