Francesca Perri - Academia.edu (original) (raw)

Papers by Francesca Perri

Research paper thumbnail of A preparation of N -Fmoc- N -methyl-α-amino acids and N -nosyl- N -methyl-α-amino acids

Amino Acids, 2010

A convenient route for the synthesis of lipophilic N-Fmoc-N-methyl-α-amino acids and N-nosyl-N-me... more A convenient route for the synthesis of lipophilic N-Fmoc-N-methyl-α-amino acids and N-nosyl-N-methyl-α-amino acids, interesting building blocks to be used for the preparation of N-methylated peptides, is presented. Both nosyl- and Fmoc-protected monomers are accessible, so these compounds can be used in solution as well as in solid phase peptide synthesis. The methodology is based on the use of benzhydryl group to protect temporarily the carboxyl function of N-nosyl-α-amino acids and on the subsequent methylation of the N-nosyl-α-amino acid benzhydryl esters with diazomethane. The benzhydryl esters offer several beneficial features such as simple preparation, stability to methylation and selective deprotection under mild conditions. The overall procedure is highly efficient in that the adopted conditions keep the chiral integrity of amino acid precursors and the process does not require chromatographic purification of the methylated products.

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Research paper thumbnail of Synthesis of Chiral Nitrones from N‐Fmoc Amino Acids and N‐Fmoc Dipeptides

Synthetic Communications, 2004

Abstract In this work is presented a synthetic procedure for the preparation of chiral nitrones f... more Abstract In this work is presented a synthetic procedure for the preparation of chiral nitrones from N‐Fmoc protected amino acids and dipeptides. The nitrone functional group can replace the carboxyl unit of amino acid and peptide systems and can be inserted into the ...

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Research paper thumbnail of N-(4-Nitrophenylsulfonyl)- and N-(Fluorenylmethoxycarbonyl)-N-ethyl Amino Acid Methyl Esters - A Practical Approach

European Journal of Organic Chemistry, 2010

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Research paper thumbnail of Comparison of the Volatile Constituents in Cold-Pressed Bergamot Oil and a Volatile Oil Isolated by Vacuum Distillation

Journal of Agricultural and Food Chemistry, 2007

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Research paper thumbnail of Reduction of N-Methoxy-N-Methylamides to the Corresponding Amines with AlCl3/LiAlH4

Cheminform, 2006

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 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

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Research paper thumbnail of Determination by gas chromatography/mass spectrometry of p-phenylenediamine in hair dyes after conversion to an imine derivative

Journal of Chromatography A, 2005

In this paper we describe an analytical method for the determination of p-phenylenediamine (PPDA)... more In this paper we describe an analytical method for the determination of p-phenylenediamine (PPDA) in hair dyes. In the adopted methodology the analyte is transformed into the corresponding imine derivative by treatment with benzaldehyde, and then analyzed by gas chromatography (GC) combined to mass spectrometry (MS), operating in SIM conditions. The direct and simultaneous chemical derivatization of the two amino functions of the analyte with benzaldehyde enhances the instrumental responses enabling the use of a sensitive and accurate method. Concentrations of PPDA in a set of commercial hair coloring creams are determined making use of N-benzylidene-4-methylbenzene-amine as a very stable internal standard which is easily prepared by condensation of 4-methylbenzene-amine with benzaldehyde. The regression calibration curves for PPDA in hair dyes are linear within 0.1 ± 25 mg/ml with 0.99 as a typical correlation coefficient.

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Research paper thumbnail of D-homoannulation of 17α,21-dihydroxy-20-keto steroids (corticosteroids

Steroids, 2006

Synthetic corticosteroids are widely used as anti-inflammatory agents. Mechanisms of their degrad... more Synthetic corticosteroids are widely used as anti-inflammatory agents. Mechanisms of their degradation continue to be studied. D-ring homoannulation is a well-known metabolic pathway for steroids in vivo. The rearrangement with aluminium trichloride of the commercial anti-inflammatory drugs hydrocortisone, cortisone and dexamethasone is here presented. The structures of the corresponding 17a-keto-17-hydroxy-D-homosteroids are established by mono- and two-dimensional NMR analysis. Inversion of the α-configuration of C-16 is observed in the Lewis acid assisted D-homoannulation of dexamethasone.

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Research paper thumbnail of Reduction of N-Methoxy-N-Methylamides to the Corresponding Amines with AlCl3/LiAlH4

Letters in Organic Chemistry, 2006

... Reduction of N-Methoxy-N-Methylamides to the Corresponding Amines with AlCl 3 /LiAlH 4 . Mari... more ... Reduction of N-Methoxy-N-Methylamides to the Corresponding Amines with AlCl 3 /LiAlH 4 . Maria Luisa Di Gioia,; Antonella Leggio,; Adolfo Le Pera,; Angelo Liguori,; Francesca Perri,; Maria Caterina Viscomi. Article first published online: 21 NOV 2006. ...

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Research paper thumbnail of An Efficient Preparation of N -Methyl-α-amino Acids from N -Nosyl-α-amino Acid Phenacyl Esters

Journal of Organic Chemistry, 2010

In this paper we describe a simple and efficient solution-phase synthesis of N-methyl-N-nosyl-alp... more In this paper we describe a simple and efficient solution-phase synthesis of N-methyl-N-nosyl-alpha-amino acids and N-Fmoc-N-methyl-alpha-amino acids. This represents a very important application in peptide synthesis to obtain N-methylated peptides in both solution and solid phase. The developed methodology involves the use of N-nosyl-alpha-amino acids with the carboxyl function protected as a phenacyl ester and the methylating reagent diazomethane. An important aspect of this synthetic strategy is the possibility to selectively deprotect the carboxyl function or alternatively both amino and carboxyl moieties by using the same reagent with a different molar excess and under mild conditions. Furthermore, the adopted procedure keeps unchanged the acid-sensitive side chain protecting groups used in Fmoc-based synthetic strategies.

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Research paper thumbnail of ChemInform Abstract: An Efficient Preparation of N-Methyl-α-amino Acids from N-Nosyl-α-amino Acid Phenacyl Esters

Cheminform, 2010

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.

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Research paper thumbnail of N-Alkylation of N-arylsulfonyl-α-amino acid methyl esters by trialkyloxonium tetrafluoroborates

Tetrahedron, 2011

In this work we present the results obtained for the N-alkylation of a series of N-arylsulfonyl-α... more In this work we present the results obtained for the N-alkylation of a series of N-arylsulfonyl-α-amino acid methyl esters bearing different substituents at the 4-position of the sulfonamide aromatic ring. In particular, we compare the reactivity of these species with diazomethane and trimethyloxonium tetrafluoroborate in N-methylation processes. Diazomethylation is unsuccessful for N-arylsulfonamide derivatives containing electron-releasing groups on the aromatic ring. In these cases trimethyloxonium tetrafluoroborate is the reagent of choice for the direct and quantitative N-methylation. Further we extend our evaluation to the use of triethyloxonium tetrafluoroborate. This reagent shows to be very efficient in order to prepare N-ethyl derivatives of N-arylsulfonyl-α-amino acid methyl esters. An experimental protocol similar to that used for N-methylation with trimethyloxonium tetrafluoroborate is applied for the N-ethylation.

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Research paper thumbnail of Steroidal seven-membered A-ring epoxy lactones by oxidation of the corresponding Δ 4-3-ketosteroids

Steroids, 2006

Treatment of Δ4-3-ketosteroids with m-chloroperbenzoic acid at 0 °C produced the corresponding st... more Treatment of Δ4-3-ketosteroids with m-chloroperbenzoic acid at 0 °C produced the corresponding steroidal seven-membered A-ring epoxy lactones. The adopted procedure allowed for efficient recovery and separation of the products with definite stereochemistry.

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Research paper thumbnail of A new non-natural arginine-like amino acid derivative with a sulfamoyl group in the side-chain

Amino Acids, 2010

Sulfamoylation of the l-ornithine methyl ester side-chain generates a non-natural arginine isoste... more Sulfamoylation of the l-ornithine methyl ester side-chain generates a non-natural arginine isostere which can be coupled with N-Fmoc-l-proline to synthesize analogues which maintain the structural characteristics of the biologically important Pro-Arg dipeptide sequence. As a probe of its biological importance, the sulfamoylated amino acid derivative was also incorporated as P1 residue in tripeptide structures matching the C-terminal subsequence of fibrinogen. The reported results demonstrate that the functionalization of l-ornithine side-chain with a neutral sulfamoyl group can generate an arginine bioisostere which can be used for the synthesis of prototypes of a new class of human thrombin inhibitors.

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Research paper thumbnail of Alternative and Chemoselective Deprotection of the ?Amino and Carboxy Functions ofN-FmocAmino Acid andN-Fmoc-Dipeptide Methyl Esters by Modulation of the Molar Ratio in the AlCl3/N,N-Dimethylaniline Reagent System

European Journal of Organic Chemistry, 2004

The selective cleavage of an ester function without removing the Fmoc protecting group on the ami... more The selective cleavage of an ester function without removing the Fmoc protecting group on the amino moiety5−21 is an important strategic element in peptide synthesis. In a previous paper,22 we reported a facile procedure for the chemoselective unblocking of the carboxy ...

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Research paper thumbnail of SolidPhase Synthesis of N -Nosyl- and N -Fmoc- N -Methyl-α-amino Acids

Journal of Organic Chemistry, 2007

We report here a convenient and simple solid-phase synthesis of N-nosyl-N-methyl-alpha-amino acid... more We report here a convenient and simple solid-phase synthesis of N-nosyl-N-methyl-alpha-amino acids and N-Fmoc-N-methyl-alpha-amino acids, important building blocks for the synthesis of conformationally restricted and protease-resistant natural peptides and peptide analogues. The methodology involves the use of 2-chlorotrityl chloride resin to temporarily protect the carboxylic group of alpha-amino acids and of diazomethane as the reagent to methylate the sulfonamidic function. The approach developed is particularly efficient also with alpha-amino acids bearing appropriately protected functionalized side chains.

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Research paper thumbnail of Synthesis of Chiral Nitrones from N-Fmoc Amino Acids and N-Fmoc Dipeptides

Cheminform, 2005

For Abstract see ChemInform Abstract in Full Text.

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Research paper thumbnail of Site-Selective Methylation of N β -Nosyl Hydrazides of N -Nosyl Protected α-Amino Acids

Journal of Organic Chemistry, 2010

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Research paper thumbnail of Extraction of Quinolizidine Alkaloids in Non Aqueous Basic Conditions: The Case of Spartium junceum Flowers

Chromatographia, 2008

In this work the use of basic nonaqueous conditions is suggested as a general method for the extr... more In this work the use of basic nonaqueous conditions is suggested as a general method for the extraction of quinolizidine alkaloids. The extraction of quinolizidine alkaloids from fresh flowers of Spartium junceum is performed in ethanolic basic conditions. The procedure is efficient and selective. The extract is essentially formed by N-formylcytisine, N-methylcytisine, cytisine and anagyrine. The method allows a high recovery of N-formylcytisine which becomes the predominant alkaloid in S. Junceum flowers.

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Research paper thumbnail of Methylation of α-Amino Acids and Derivatives Using Trimethylsilyldiazomethane

Chemical Biology & Drug Design, 2009

A study of the methylation of N-nosyl-α-amino acids and derivatives with trimethylsilyldiazometha... more A study of the methylation of N-nosyl-α-amino acids and derivatives with trimethylsilyldiazomethane is here reported. Trimethylsilyldiazomethane allows the chemo-specific methylation of the carboxyl function of N-nosyl-α-amino acids in high yields and purity. This method provides a practical route to N-methyl-α-amino acids avoiding the use of the more toxic and explosive diazomethane. This simple and safe methylation methodology of α-amino acids and derivatives is not limited to organic synthesis and involves the use of a commercially available reagent as well.

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Research paper thumbnail of N Methyl N -nosyl-β 3 -amino Acids

Journal of Organic Chemistry, 2007

N-Methyl-beta(3)-amino acids are important building blocks in the synthesis of biologically activ... more N-Methyl-beta(3)-amino acids are important building blocks in the synthesis of biologically active molecules. A very simple and efficient approach to transform natural alpha-amino acids into their corresponding N-methyl-beta(3)-amino acids is here presented. In the method, the key intermediates N-methyl-N-nosyl-alpha-aminoacyldiazomethanes are prepared in only one step, by a simple treatment of the corresponding N-nosyl-alpha-aminoacyl chlorides with diazomethane. The synthetic route takes advantage from the use of the nosyl group. This N-masking moiety activates the NH function, and the N-methylation can directly occur during the acylation step of diazomethane, rendering useless a second step that instead is shown to be necessary in all the classical procedures already reported for the preparation of N-methyl-beta(3)-amino acids. The Wolff rearrangement of N-methyl-N-nosyl-alpha-aminoacyldiazomethanes provides the corresponding N-methyl-N-nosyl-beta(3)-amino acids with total retention of the chiral configuration of the starting alpha-amino acids. No epimerization of the chiral carbon atom is observed also when N-methyl-N-nosyl-beta(3)-amino acids are transformed into chlorides and coupled with alpha-amino acid methyl esters to achieve model scaffolds for biologically important modified peptides.

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Research paper thumbnail of A preparation of N -Fmoc- N -methyl-α-amino acids and N -nosyl- N -methyl-α-amino acids

Amino Acids, 2010

A convenient route for the synthesis of lipophilic N-Fmoc-N-methyl-α-amino acids and N-nosyl-N-me... more A convenient route for the synthesis of lipophilic N-Fmoc-N-methyl-α-amino acids and N-nosyl-N-methyl-α-amino acids, interesting building blocks to be used for the preparation of N-methylated peptides, is presented. Both nosyl- and Fmoc-protected monomers are accessible, so these compounds can be used in solution as well as in solid phase peptide synthesis. The methodology is based on the use of benzhydryl group to protect temporarily the carboxyl function of N-nosyl-α-amino acids and on the subsequent methylation of the N-nosyl-α-amino acid benzhydryl esters with diazomethane. The benzhydryl esters offer several beneficial features such as simple preparation, stability to methylation and selective deprotection under mild conditions. The overall procedure is highly efficient in that the adopted conditions keep the chiral integrity of amino acid precursors and the process does not require chromatographic purification of the methylated products.

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Research paper thumbnail of Synthesis of Chiral Nitrones from N‐Fmoc Amino Acids and N‐Fmoc Dipeptides

Synthetic Communications, 2004

Abstract In this work is presented a synthetic procedure for the preparation of chiral nitrones f... more Abstract In this work is presented a synthetic procedure for the preparation of chiral nitrones from N‐Fmoc protected amino acids and dipeptides. The nitrone functional group can replace the carboxyl unit of amino acid and peptide systems and can be inserted into the ...

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Research paper thumbnail of N-(4-Nitrophenylsulfonyl)- and N-(Fluorenylmethoxycarbonyl)-N-ethyl Amino Acid Methyl Esters - A Practical Approach

European Journal of Organic Chemistry, 2010

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Research paper thumbnail of Comparison of the Volatile Constituents in Cold-Pressed Bergamot Oil and a Volatile Oil Isolated by Vacuum Distillation

Journal of Agricultural and Food Chemistry, 2007

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Research paper thumbnail of Reduction of N-Methoxy-N-Methylamides to the Corresponding Amines with AlCl3/LiAlH4

Cheminform, 2006

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 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

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Research paper thumbnail of Determination by gas chromatography/mass spectrometry of p-phenylenediamine in hair dyes after conversion to an imine derivative

Journal of Chromatography A, 2005

In this paper we describe an analytical method for the determination of p-phenylenediamine (PPDA)... more In this paper we describe an analytical method for the determination of p-phenylenediamine (PPDA) in hair dyes. In the adopted methodology the analyte is transformed into the corresponding imine derivative by treatment with benzaldehyde, and then analyzed by gas chromatography (GC) combined to mass spectrometry (MS), operating in SIM conditions. The direct and simultaneous chemical derivatization of the two amino functions of the analyte with benzaldehyde enhances the instrumental responses enabling the use of a sensitive and accurate method. Concentrations of PPDA in a set of commercial hair coloring creams are determined making use of N-benzylidene-4-methylbenzene-amine as a very stable internal standard which is easily prepared by condensation of 4-methylbenzene-amine with benzaldehyde. The regression calibration curves for PPDA in hair dyes are linear within 0.1 ± 25 mg/ml with 0.99 as a typical correlation coefficient.

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Research paper thumbnail of D-homoannulation of 17α,21-dihydroxy-20-keto steroids (corticosteroids

Steroids, 2006

Synthetic corticosteroids are widely used as anti-inflammatory agents. Mechanisms of their degrad... more Synthetic corticosteroids are widely used as anti-inflammatory agents. Mechanisms of their degradation continue to be studied. D-ring homoannulation is a well-known metabolic pathway for steroids in vivo. The rearrangement with aluminium trichloride of the commercial anti-inflammatory drugs hydrocortisone, cortisone and dexamethasone is here presented. The structures of the corresponding 17a-keto-17-hydroxy-D-homosteroids are established by mono- and two-dimensional NMR analysis. Inversion of the α-configuration of C-16 is observed in the Lewis acid assisted D-homoannulation of dexamethasone.

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Research paper thumbnail of Reduction of N-Methoxy-N-Methylamides to the Corresponding Amines with AlCl3/LiAlH4

Letters in Organic Chemistry, 2006

... Reduction of N-Methoxy-N-Methylamides to the Corresponding Amines with AlCl 3 /LiAlH 4 . Mari... more ... Reduction of N-Methoxy-N-Methylamides to the Corresponding Amines with AlCl 3 /LiAlH 4 . Maria Luisa Di Gioia,; Antonella Leggio,; Adolfo Le Pera,; Angelo Liguori,; Francesca Perri,; Maria Caterina Viscomi. Article first published online: 21 NOV 2006. ...

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Research paper thumbnail of An Efficient Preparation of N -Methyl-α-amino Acids from N -Nosyl-α-amino Acid Phenacyl Esters

Journal of Organic Chemistry, 2010

In this paper we describe a simple and efficient solution-phase synthesis of N-methyl-N-nosyl-alp... more In this paper we describe a simple and efficient solution-phase synthesis of N-methyl-N-nosyl-alpha-amino acids and N-Fmoc-N-methyl-alpha-amino acids. This represents a very important application in peptide synthesis to obtain N-methylated peptides in both solution and solid phase. The developed methodology involves the use of N-nosyl-alpha-amino acids with the carboxyl function protected as a phenacyl ester and the methylating reagent diazomethane. An important aspect of this synthetic strategy is the possibility to selectively deprotect the carboxyl function or alternatively both amino and carboxyl moieties by using the same reagent with a different molar excess and under mild conditions. Furthermore, the adopted procedure keeps unchanged the acid-sensitive side chain protecting groups used in Fmoc-based synthetic strategies.

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Research paper thumbnail of ChemInform Abstract: An Efficient Preparation of N-Methyl-α-amino Acids from N-Nosyl-α-amino Acid Phenacyl Esters

Cheminform, 2010

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.

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Research paper thumbnail of N-Alkylation of N-arylsulfonyl-α-amino acid methyl esters by trialkyloxonium tetrafluoroborates

Tetrahedron, 2011

In this work we present the results obtained for the N-alkylation of a series of N-arylsulfonyl-α... more In this work we present the results obtained for the N-alkylation of a series of N-arylsulfonyl-α-amino acid methyl esters bearing different substituents at the 4-position of the sulfonamide aromatic ring. In particular, we compare the reactivity of these species with diazomethane and trimethyloxonium tetrafluoroborate in N-methylation processes. Diazomethylation is unsuccessful for N-arylsulfonamide derivatives containing electron-releasing groups on the aromatic ring. In these cases trimethyloxonium tetrafluoroborate is the reagent of choice for the direct and quantitative N-methylation. Further we extend our evaluation to the use of triethyloxonium tetrafluoroborate. This reagent shows to be very efficient in order to prepare N-ethyl derivatives of N-arylsulfonyl-α-amino acid methyl esters. An experimental protocol similar to that used for N-methylation with trimethyloxonium tetrafluoroborate is applied for the N-ethylation.

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Research paper thumbnail of Steroidal seven-membered A-ring epoxy lactones by oxidation of the corresponding Δ 4-3-ketosteroids

Steroids, 2006

Treatment of Δ4-3-ketosteroids with m-chloroperbenzoic acid at 0 °C produced the corresponding st... more Treatment of Δ4-3-ketosteroids with m-chloroperbenzoic acid at 0 °C produced the corresponding steroidal seven-membered A-ring epoxy lactones. The adopted procedure allowed for efficient recovery and separation of the products with definite stereochemistry.

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Research paper thumbnail of A new non-natural arginine-like amino acid derivative with a sulfamoyl group in the side-chain

Amino Acids, 2010

Sulfamoylation of the l-ornithine methyl ester side-chain generates a non-natural arginine isoste... more Sulfamoylation of the l-ornithine methyl ester side-chain generates a non-natural arginine isostere which can be coupled with N-Fmoc-l-proline to synthesize analogues which maintain the structural characteristics of the biologically important Pro-Arg dipeptide sequence. As a probe of its biological importance, the sulfamoylated amino acid derivative was also incorporated as P1 residue in tripeptide structures matching the C-terminal subsequence of fibrinogen. The reported results demonstrate that the functionalization of l-ornithine side-chain with a neutral sulfamoyl group can generate an arginine bioisostere which can be used for the synthesis of prototypes of a new class of human thrombin inhibitors.

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Research paper thumbnail of Alternative and Chemoselective Deprotection of the ?Amino and Carboxy Functions ofN-FmocAmino Acid andN-Fmoc-Dipeptide Methyl Esters by Modulation of the Molar Ratio in the AlCl3/N,N-Dimethylaniline Reagent System

European Journal of Organic Chemistry, 2004

The selective cleavage of an ester function without removing the Fmoc protecting group on the ami... more The selective cleavage of an ester function without removing the Fmoc protecting group on the amino moiety5−21 is an important strategic element in peptide synthesis. In a previous paper,22 we reported a facile procedure for the chemoselective unblocking of the carboxy ...

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Research paper thumbnail of SolidPhase Synthesis of N -Nosyl- and N -Fmoc- N -Methyl-α-amino Acids

Journal of Organic Chemistry, 2007

We report here a convenient and simple solid-phase synthesis of N-nosyl-N-methyl-alpha-amino acid... more We report here a convenient and simple solid-phase synthesis of N-nosyl-N-methyl-alpha-amino acids and N-Fmoc-N-methyl-alpha-amino acids, important building blocks for the synthesis of conformationally restricted and protease-resistant natural peptides and peptide analogues. The methodology involves the use of 2-chlorotrityl chloride resin to temporarily protect the carboxylic group of alpha-amino acids and of diazomethane as the reagent to methylate the sulfonamidic function. The approach developed is particularly efficient also with alpha-amino acids bearing appropriately protected functionalized side chains.

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Research paper thumbnail of Synthesis of Chiral Nitrones from N-Fmoc Amino Acids and N-Fmoc Dipeptides

Cheminform, 2005

For Abstract see ChemInform Abstract in Full Text.

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Research paper thumbnail of Site-Selective Methylation of N β -Nosyl Hydrazides of N -Nosyl Protected α-Amino Acids

Journal of Organic Chemistry, 2010

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Research paper thumbnail of Extraction of Quinolizidine Alkaloids in Non Aqueous Basic Conditions: The Case of Spartium junceum Flowers

Chromatographia, 2008

In this work the use of basic nonaqueous conditions is suggested as a general method for the extr... more In this work the use of basic nonaqueous conditions is suggested as a general method for the extraction of quinolizidine alkaloids. The extraction of quinolizidine alkaloids from fresh flowers of Spartium junceum is performed in ethanolic basic conditions. The procedure is efficient and selective. The extract is essentially formed by N-formylcytisine, N-methylcytisine, cytisine and anagyrine. The method allows a high recovery of N-formylcytisine which becomes the predominant alkaloid in S. Junceum flowers.

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Research paper thumbnail of Methylation of α-Amino Acids and Derivatives Using Trimethylsilyldiazomethane

Chemical Biology & Drug Design, 2009

A study of the methylation of N-nosyl-α-amino acids and derivatives with trimethylsilyldiazometha... more A study of the methylation of N-nosyl-α-amino acids and derivatives with trimethylsilyldiazomethane is here reported. Trimethylsilyldiazomethane allows the chemo-specific methylation of the carboxyl function of N-nosyl-α-amino acids in high yields and purity. This method provides a practical route to N-methyl-α-amino acids avoiding the use of the more toxic and explosive diazomethane. This simple and safe methylation methodology of α-amino acids and derivatives is not limited to organic synthesis and involves the use of a commercially available reagent as well.

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Research paper thumbnail of N Methyl N -nosyl-β 3 -amino Acids

Journal of Organic Chemistry, 2007

N-Methyl-beta(3)-amino acids are important building blocks in the synthesis of biologically activ... more N-Methyl-beta(3)-amino acids are important building blocks in the synthesis of biologically active molecules. A very simple and efficient approach to transform natural alpha-amino acids into their corresponding N-methyl-beta(3)-amino acids is here presented. In the method, the key intermediates N-methyl-N-nosyl-alpha-aminoacyldiazomethanes are prepared in only one step, by a simple treatment of the corresponding N-nosyl-alpha-aminoacyl chlorides with diazomethane. The synthetic route takes advantage from the use of the nosyl group. This N-masking moiety activates the NH function, and the N-methylation can directly occur during the acylation step of diazomethane, rendering useless a second step that instead is shown to be necessary in all the classical procedures already reported for the preparation of N-methyl-beta(3)-amino acids. The Wolff rearrangement of N-methyl-N-nosyl-alpha-aminoacyldiazomethanes provides the corresponding N-methyl-N-nosyl-beta(3)-amino acids with total retention of the chiral configuration of the starting alpha-amino acids. No epimerization of the chiral carbon atom is observed also when N-methyl-N-nosyl-beta(3)-amino acids are transformed into chlorides and coupled with alpha-amino acid methyl esters to achieve model scaffolds for biologically important modified peptides.

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