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Li W, Lu F, Zhang X. Vapor-phase catalytic methylation of 1,1,1,3,3,3-hexafluoroisopropanol for the mass production of 1,1,1,3,3,3-hexafluoroisopropyl methyl ether. J Fluor Chem 2021. [DOI: 10.1016/j.jfluchem.2020.109673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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2
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Duan X, Huang Z, Qian G, He K, Zhang J, Mleczko L, Zhou X. Unprecedented yield of methyl-esterification with in-situ generated diazomethane in a microchannel reactor with methanol as solvent. Chem Eng Sci 2020. [DOI: 10.1016/j.ces.2019.115397] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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3
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Um IH, Moon HJ, Shin YH, Dust JM. Medium effect on the α-effect for nucleophilic substitution reactions of p-nitrophenyl acetate with benzohydroxamates and m-chlorophenoxide in DMSO–H2O mixtures as contrasts with MeCN–H2O mixtures: comparing two very different polar aprotic solvent components. CAN J CHEM 2018. [DOI: 10.1139/cjc-2018-0103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A kinetic study is reported on nucleophilic substitution reactions of p-nitrophenyl acetate (1a) with three α-effect nucleophiles, benzohydroxamate (BHA–), p-methylbenzohydroxamate (MBHA–), and p-methyl-N-methylbenzohydroxamate (M2BHA–), and a reference nucleophile, m-chlorophenoxide (m-ClPhO–), in DMSO–H2O mixtures of varying compositions at 25.0 ± 0.1 °C. Second-order rate constants for the reactions with BHA– and MBHA– decrease upon addition of DMSO to the reaction medium up to 60 mol % DMSO and then increase thereafter only a little. In contrast, M2BHA– and m-ClPhO– become much more reactive as the DMSO content in the medium increases. Such contrasting medium effects on reactivity are consistent with the report that hydroxamic acids behave as OH acids in H2O but as NH acids in dipolar aprotic solvents (e.g., DMSO and MeCN). It has been concluded that BHA– and MBHA– form an equilibrium of a reactive form I with less reactive species II in DMSO–H2O mixtures and the position of the equilibrium is dependent on solvent compositions. BHA– and MBHA– exhibit the α-effect in H2O but not in in 90 mol % DMSO. In contrast, the α-effect yielded by M2BHA– increases steeply up to 70 mol % DMSO and then levels off thereafter.
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Affiliation(s)
- Ik-Hwan Um
- Department of Chemistry, Ewha Womans University, Seoul 03767, Korea
| | - Hyun-Jung Moon
- Department of Chemistry, Ewha Womans University, Seoul 03767, Korea
| | - Young-Hee Shin
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Julian M. Dust
- Departments of Chemistry and Environmental Science, Grenfell Campus-Memorial University of Newfoundland, Corner Brook, NL A2H 5G4, Canada
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Sharma A, Kumar A, Abdel Monaim SAH, Jad YE, El-Faham A, de la Torre BG, Albericio F. N-methylation in amino acids and peptides: Scope and limitations. Biopolymers 2018. [PMID: 29528112 DOI: 10.1002/bip.23110] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Active pharmaceutical ingredients (APIs) can be divided into two types, namely chemical and biological entities. Traditionally, the former has been associated with the so-called small molecules. The revival of peptides in pharmaceutical industry results from their importance in many biological roles. However, low metabolic stability and the lack of oral availability of most peptides is the main drawback for peptide to fulfill that paradigmatic situation. In this regard, efforts are being channeled into addressing this issue by introducing restrictions into the flexible peptide backbone, mainly through N-methyl amino acids (NMAAs) or development of small cyclic peptides. In many cases, both the above restrictions are combined with the aim to enhance oral availability. The synthesis of NMAAs is complex and their introduction into the peptide chain brings additional synthetic challenges and also sometimes leads to side-reactions. Here we discuss the most efficient methods for the synthesis of NMAAs (either in solution or in solid phase) and also their introduction into peptide sequences. Special attention is also given to the detection of side reactions and the most efficient way to prevent them.
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Affiliation(s)
- Anamika Sharma
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa
| | - Ashish Kumar
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa.,School of Chemistry and Physics, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa
| | - Shimaa A H Abdel Monaim
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa
| | - Yahya E Jad
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa
| | - Ayman El-Faham
- Department of Chemistry, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.,Department of Chemistry, Faculty of Science, Alexandria University, Ibrahimia, Alexandria, 21321, Egypt
| | - Beatriz G de la Torre
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa.,KRISP, College of Health Sciences, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa
| | - Fernando Albericio
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa.,School of Chemistry and Physics, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa.,Department of Chemistry, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.,Department of Organic Chemistry, University of Barcelona, Martí i Franqués 1-11, Barcelona, 08028, Spain.,CIBER-BBN, Networking Centre on Bioengineering, Biomaterials and Nanomedicine, Barcelona Science Park, Baldiri Reixac 10, Barcelona, 08028, Spain
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5
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Molleti J, Yadav GD. Green Synthesis of Veratraldehyde Using Potassium Promoted Lanthanum–Magnesium Mixed Oxide Catalyst. Org Process Res Dev 2017. [DOI: 10.1021/acs.oprd.7b00127] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jayaram Molleti
- Department of Chemical Engineering, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga Mumbai-400 019, India
| | - Ganapati D. Yadav
- Department of Chemical Engineering, Institute of Chemical Technology, Nathalal Parekh Marg, Matunga Mumbai-400 019, India
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Leggio A, Alò D, Belsito EL, Di Gioia ML, Romio E, Siciliano C, Liguori A. Lewis acid catalysed methylation ofN-(9H-fluoren-9-yl)methanesulfonyl (Fms) protected lipophilicα-amino acid methyl esters. J Pept Sci 2015; 21:644-50. [DOI: 10.1002/psc.2777] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/04/2015] [Accepted: 03/09/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Antonella Leggio
- Dipartimento di Farmacia e Scienze della Salute e della Nutrizione; Università della Calabria; Ed. Polifunzionale Rende CS I-87036 Italy
| | - Danila Alò
- Dipartimento di Farmacia e Scienze della Salute e della Nutrizione; Università della Calabria; Ed. Polifunzionale Rende CS I-87036 Italy
| | - Emilia Lucia Belsito
- Dipartimento di Farmacia e Scienze della Salute e della Nutrizione; Università della Calabria; Ed. Polifunzionale Rende CS I-87036 Italy
| | - Maria Luisa Di Gioia
- Dipartimento di Farmacia e Scienze della Salute e della Nutrizione; Università della Calabria; Ed. Polifunzionale Rende CS I-87036 Italy
| | - Emanuela Romio
- Dipartimento di Farmacia e Scienze della Salute e della Nutrizione; Università della Calabria; Ed. Polifunzionale Rende CS I-87036 Italy
| | - Carlo Siciliano
- Dipartimento di Farmacia e Scienze della Salute e della Nutrizione; Università della Calabria; Ed. Polifunzionale Rende CS I-87036 Italy
| | - Angelo Liguori
- Dipartimento di Farmacia e Scienze della Salute e della Nutrizione; Università della Calabria; Ed. Polifunzionale Rende CS I-87036 Italy
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Di Gioia ML, Barattucci A, Bonaccorsi P, Leggio A, Minuti L, Romio E, Temperini A, Siciliano C. Deprotection/reprotection of the amino group in α-amino acids and peptides. A one-pot procedure in [Bmim][BF4] ionic liquid. RSC Adv 2014. [DOI: 10.1039/c3ra46599c] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Spinella M, De Marco R, Belsito EL, Leggio A, Liguori A. The dimethylsulfoxonium methylide as unique reagent for the simultaneous deprotection of amino and carboxyl function of N-Fmoc-α-amino acid and N-Fmoc-peptide esters. Tetrahedron 2013. [DOI: 10.1016/j.tet.2012.12.052] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Quantitative determination of fatty acid chain composition in pork meat products by high resolution 1H NMR spectroscopy. Food Chem 2012; 136:546-54. [PMID: 23122096 DOI: 10.1016/j.foodchem.2012.08.058] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 05/02/2012] [Accepted: 08/22/2012] [Indexed: 01/06/2023]
Abstract
High resolution (1)H NMR spectroscopy was proposed for the determination of the fatty acid chain profile of lipids in pork meat products during ripening. Two typical Mediterranean PDO salami produced in Calabria, a region in the Southern Italy, were chosen as a case of study. Quantitative NMR analysis provided the fatty acid chain profiles of total lipid extracts. The transesterification of total lipid extracts furnished FAME mixtures that enabled quantitation of fatty acid acyl chains in the acylglycerol and FFA portions. In all cases, oleyl chains were predominant, and high amounts of polyunsaturated fatty acid chains were observed. The proposed spectroscopic method allowed also the estimation of the most important nutritional parameters of dry fermented meat products.
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Leggio A, Belsito EL, De Marco R, Liguori A, Siciliano C, Spinella M. Simultaneous extraction and derivatization of amino acids and free fatty acids in meat products. J Chromatogr A 2012; 1241:96-102. [PMID: 22560349 DOI: 10.1016/j.chroma.2012.04.029] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 04/05/2012] [Accepted: 04/06/2012] [Indexed: 11/24/2022]
Abstract
In meat products the contents of free amino acids and free fatty acids are two important parameters used to establish their quality. These compounds play a very important role in defining the sensorial characteristics and acceptability of meat products. An innovative procedure for the measurement of free amino acid and fatty acid contents in meat and meat derivatives was developed. A single experiment can be performed in order to determine simultaneously the free amino acid and free fatty acid profiles. The analytes of interest are rapidly extracted from the meat matrix and derivatized by using methyl chloroformate. This reagent allows the transformation of the two groups of analytes into the corresponding N-methyloxycarbonyl amino acid methyl esters and fatty acid methyl esters that can easily be extracted and sampled for their further identification and quantitation. The measurement of the obtained amino acid and fatty acid derivatives is performed by GC/MS analysis and their concentrations are calculated by using two appropriate internal standards. The main advantage of the proposed protocol is the determination at the same time of two important classes of analytes that are of great importance in food analysis and characterization. Moreover, minimal sample manipulation and preparation, and reduced total extraction times are required to obtain the response with respect to conventional procedures, in which instead the analysis of both the two classes of compounds must be performed separately. The helpfulness of the protocol was tested in the analysis of a cured meat product that is typical of the South of Italy. The optimized protocol successfully allowed the determination of thirteen free amino acids and six free fatty acids, namely those most abundant in the lipid content of the cured meat product under evaluation.
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Affiliation(s)
- Antonella Leggio
- Dipartimento di Scienze Farmaceutiche, Università della Calabria, Edificio Polifunzionale, I-87030 Arcavacata di Rende, CS, Italy
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De Marco R, Di Gioia ML, Liguori A, Perri F, Siciliano C, Spinella M. N-Alkylation of N-arylsulfonyl-α-amino acid methyl esters by trialkyloxonium tetrafluoroborates. Tetrahedron 2011. [DOI: 10.1016/j.tet.2011.10.042] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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12
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Martynaitis V, Steponavičiūtė R, Krikštolaitytė S, Solovjova J, Mangelinckx S, De Kimpe N, Holzer W, Šačkus A. Synthesis and reactions of 1-hydroxy-9,9a-dihydro-1H-imidazo[1,2-a]indol-2-(3H)-ones. Tetrahedron 2011. [DOI: 10.1016/j.tet.2011.03.044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Aoyama T, Hari Y, Yokoyama T. Synthesis of 3-Substituted 3-(Trimethylsiloxy)pyrrolidines from β-Aminoketones and Lithium Trimethylsilyldiazomethane. HETEROCYCLES 2010. [DOI: 10.3987/com-09-s(s)70] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Yang CY, Chen HL, Ho JJ. Quantum-chemical calculations of the methylation of hydroxamic and thiohydroxamic acids with diazomethane. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.theochem.2006.08.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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15
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Gioia MLD, Leggio A, Pera AL, Liguori A, Perri F. Occurrence of Organic Compounds in the Thermal Sulfurous Waters of Calabria, Italy. Chromatographia 2006. [DOI: 10.1365/s10337-006-0806-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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16
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Di Gioia ML, Leggio A, Liguori A. N-Methylation of Peptides on Selected Positions during the Elongation of the Peptide Chain in Solution Phase. J Org Chem 2005; 70:3892-7. [PMID: 15876076 DOI: 10.1021/jo0478959] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[reactions: see text] An efficient and general solution-phase method for the site-specific N-methylation of peptides has been developed. This novel procedure involves synthesis of N-nosyl protected peptides and their subsequent N-methylation with diazomethane. Its efficiency was proved by the successful synthesis of various hindered oligopeptides containing N-methyl amino acid residues with excellent yield and purity. The method is particularly attractive in that the adopted conditions do not cause any detectable racemization of the peptide stereocenters and the process does not require chromatographic purification of the methylated products. A further advantage is the compatibility of this methodology with Fmoc solution-phase peptide synthesis.
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Affiliation(s)
- M Luisa Di Gioia
- Dipartimento di Scienze Farmaceutiche, Università della Calabria, Via Ponte P. Bucci cubo 15/C, I-87036 Arcavacata di Rende (CS), Italy
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Rajabi F, Saidi MR. Microwave‐Assisted Methylation of Carboxylic Acids and Phenolic Compounds with Dimethyl‐Carbonate Under Solvent‐Free Condition. SYNTHETIC COMMUN 2004. [DOI: 10.1081/scc-200036622] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Johnson JE, Dolliver DD, Yu L, Canseco DC, McAllister MA, Rowe JE. Mechanism of methoxide ion substitution in the z and e isomers of o-methylbenzohydroximoyl halides. J Org Chem 2004; 69:2741-9. [PMID: 15074922 DOI: 10.1021/jo030299e] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Kinetics and stereochemical studies have been carried out on the reactions of the Z and E isomers of O-methylbenzohydroximoyl halides [1Z and 1E, ArC(X)=NOCH(3)] with sodium methoxide in 9:1 DMSO-methanol. The reactions of methoxide ion with hydroximoyl fluorides (X = F) are stereospecific. The reaction with 1Z (X = F) gives only the Z substitution product (1Z, X =OCH(3)). The reaction of methoxide ion with 1E (X = F) is less selective, giving ca. 85% E substitution product. The Hammett rho-values for the Z and E isomers (X = F) are +2.94 and +3.30, respectively. The element effects for 1Z (Ar = C(6)H(5)) are 2.21 (X = Br):1.00 (X = Cl):79.7 (X = F). The 1E element effects are (Ar = C(6)H(5)) 1.00 (X = Cl):18.3 (X = F) and (Ar = 4-CH(3)OC(6)H(4)) 1.97 (X = Br):1.00 (X = Cl):12.1 (X = F). The entropies of activation for these reactions are negative (for example, DeltaS() = -15 eu for 1Z and DeltaS() = -14 eu for 1E, Ar = 4-CH(3)OC(6)H(4), X = F). These experimental observations are consistent with a mechanism proceeding through a tetrahedral intermediate. Ab initio calculations were carried out to help explain the stereospecificity of these reactions. These calculations indicate that the tetrahedral intermediate from the Z isomer undergoes rapid elimination to the Z substitution product before stereomutation can take place. These calculations also show that the lowest barrier for rotation around the carbon-nitrogen single bond in the tetrahedral intermediate derived from 1E leads to an intermediate that eliminates fluoride ion to give E product.
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Affiliation(s)
- James E Johnson
- Department of Chemistry and Physics, Texas Woman's University, Denton, Texas 76204-5859, USA.
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Di Gioia ML, Leggio A, Le Pera A, Liguori A, Napoli A, Siciliano C, Sindona G. "One-pot" methylation of N-Nosyl-alpha-amino acid methyl esters with diazomethane and their coupling to prepare N-methyl dipeptides. J Org Chem 2003; 68:7416-21. [PMID: 12968894 DOI: 10.1021/jo034233v] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
N-Nosyl-alpha-amino acid methyl esters are methylated quantitatively with diazomethane. After proper deprotection of the amino function by treatment with the reagent system mercaptoacetic acid/sodium methoxide, the obtained N-methyl amino acid methyl esters are coupled with N-Fmoc amino acid chlorides to afford the corresponding dipeptides. The obtained products do not show any detectable extent of racemization by (1)H NMR and HPLC.
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Affiliation(s)
- Maria Luisa Di Gioia
- Dipartimento di Scienze Farmaceutiche and Dipartimento di Chimica, Università degli Studi della Calabria, Via Ponte P. Bucci, Cubo 15/C, I-87036 Arcavacata di Rende (CS), Italy
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A theoretical approach to the regioselectivity in 1,3-dipolar cycloadditions of diazoalkanes, hydrazoic acid and nitrous oxide to acetylenes, phosphaalkynes and cyanides. J PHYS ORG CHEM 2003. [DOI: 10.1002/poc.653] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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