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Miranda MS, Duarte DJ, Esteves da Silva JC, Liebman JF. Protonated heterocyclic derivatives of cyclopropane and cyclopropanone: classical species, alternate sites, and ring fragmentation. CAN J CHEM 2015. [DOI: 10.1139/cjc-2015-0029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A computational study has been performed for protonated oxygen- or nitrogen-containing heterocyclic derivatives of cyclopropane and cyclopropanone. We have searched for the most stable conformations of the protonated species using density functional theory with the B3LYP functional and the 6-31G(2df,p) basis set. More accurate enthalpy values were obtained from G4 calculations. Proton affinities and gas-phase basicities were accordingly derived.
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Affiliation(s)
- Margarida S. Miranda
- Centro de Investigação em Química, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, s/n, P-4169-007 Porto, Portugal
| | - Darío J.R. Duarte
- Laboratorio de Estructura Molecular y Propiedades, Área de Química Física-Departamento de Química, Facultad de Ciencias Exactas y Naturales y Agrimensura, Universidad Nacional del Nordeste, Avenida Libertad 5460, (3400) Corrientes, Argentina
| | - Joaquim C.G. Esteves da Silva
- Centro de Investigação em Química, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, s/n, P-4169-007 Porto, Portugal
| | - Joel F. Liebman
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
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Miranda MS, Ferreira PJ, Esteves da Silva JC, Liebman JF. Three-membered ring amides — a calculational and conceptual study of the structure and energetics of 1,2-oxaziridine-3-one and aziridine-2,3-dione. CAN J CHEM 2015. [DOI: 10.1139/cjc-2014-0321] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Species with three-membered rings and the amide linkage are well studied. A quick perusal of the literature with SciFinder finds some 50 000 references to cyclopropanes and almost 300 000 references to amides. In the current paper, we discuss the structure and energetics of two understudied three-membered ring amides, 1,2-oxaziridine-3-one (5) (simultaneously describable as the simplest cyclic carbamate and simplest hydroxamate) and aziridine-2,3-dione (7) (simultaneously describable as the simplest imide and simplest α-ketoamide), with but 5 and nearly 10 references, respectively, for these two classes of compounds. Neither 1,2-oxaziridine-3-one (5) nor aziridine-2,3-dione (7), nor any derivative thereof, has been isolated. Calculational theory ameliorates the paucity of experimental information. The current study reports our computational findings for these and related species (e.g., enols and imidols) where we have used the G3(MP2)//B3LYP method.
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Affiliation(s)
- Margarida S. Miranda
- Centro de Investigação em Química, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, s/n, P-4169-007 Porto, Portugal
| | - Paulo J.O. Ferreira
- Centro de Investigação em Química, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, s/n, P-4169-007 Porto, Portugal
| | - Joaquim C.G. Esteves da Silva
- Centro de Investigação em Química, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, s/n, P-4169-007 Porto, Portugal
| | - Joel F. Liebman
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
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Affiliation(s)
- Michal Szostak
- Department of Medicinal Chemistry, University of Kansas, Delbert M. Shankel Structural Biology Center, 2034 Becker Drive, Lawrence, Kansas 66047
| | - Jeffrey Aubé
- Department of Medicinal Chemistry, University of Kansas, Delbert M. Shankel Structural Biology Center, 2034 Becker Drive, Lawrence, Kansas 66047
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Ramesh M, Raju B, Srinivas R, Sureshbabu VV, Vishwanatha TM, Hemantha HP. Characterization of Nα-Fmoc-protected dipeptide isomers by electrospray ionization tandem mass spectrometry (ESI-MS(n)): effect of protecting group on fragmentation of dipeptides. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2011; 25:1949-1958. [PMID: 21698678 DOI: 10.1002/rcm.5076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A series of positional isomeric pairs of Fmoc-protected dipeptides, Fmoc-Gly-Xxx-OY/Fmoc-Xxx-Gly-OY (Xxx=Ala, Val, Leu, Phe) and Fmoc-Ala-Xxx-OY/Fmoc-Xxx-Ala-OY (Xxx=Leu, Phe) (Fmoc=[(9-fluorenylmethyl)oxy]carbonyl) and Y=CH(3)/H), have been characterized and differentiated by both positive and negative ion electrospray ionization ion-trap tandem mass spectrometry (ESI-IT-MS(n)). In contrast to the behavior of reported unprotected dipeptide isomers which mainly produce y(1)(+) and/or a(1)(+) ions, the protonated Fmoc-Xxx-Gly-OY, Fmoc-Ala-Xxx-OY and Fmoc-Xxx-Ala-OY yield significant b(1)(+) ions. These ions are formed, presumably with stable protonated aziridinone structures. However, the peptides with Gly- at the N-terminus do not form b(1)(+) ions. The [M+H](+) ions of all the peptides undergo a McLafferty-type rearrangement followed by loss of CO(2) to form [M+H-Fmoc+H](+). The MS(3) collision-induced dissociation (CID) of these ions helps distinguish the pairs of isomeric dipeptides studied in this work. Further, negative ion MS(3) CID has also been found to be useful for differentiating these isomeric peptide acids. The MS(3) of [M-H-Fmoc+H](-) of isomeric peptide acids produce c(1)(-), z(1)(-) and y(1)(-) ions. Thus the present study of Fmoc-protected peptides provides additional information on mass spectral characterization of the dipeptides and distinguishes the positional isomers.
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Affiliation(s)
- M Ramesh
- National Centre for Mass Spectrometry, Indian Institute of Chemical Technology, Hyderabad 500 607, India
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Harrison AG. To b or not to b: the ongoing saga of peptide b ions. MASS SPECTROMETRY REVIEWS 2009; 28:640-654. [PMID: 19338048 DOI: 10.1002/mas.20228] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Modern soft ionization techniques readily produce protonated or multiply protonated peptides. Collision-induced dissociation (CID) of these protonated species is often used as a method to obtain sequence information. In many cases fragmentation occurs at amide bonds. When the charge resides on the C-terminal fragment so-called y ions are produced which are known to be protonated amino acids or truncated peptides. When the charge resides on the N-terminal fragment so-called b ions are produced. Often the sequence of y and b ions are essential for peptide sequencing. The b ions have many possible structures, a knowledge of which is useful in this sequencing. The structures of b ions are reviewed in the following with particular emphasis on the variation of structure with the number of amino acid residues in the b ion and the effect of peptide side chain on b ion structure. The recent discovery of full cyclization of larger b ions results in challenges in peptide sequencing. This aspect is discussed in detail.
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Affiliation(s)
- Alex G Harrison
- Department of Chemistry, University of Toronto, Toronto, ON, Canada.
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Jean Y, Demachy I, Lledos A, Maseras F. Electronic against steric effects in distorted amides. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s0166-1280(03)00294-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Würthwein EU, Hergenröther T, Quast H. exo/endoPreferences of Double Bonds in Three-Membered Ring Compounds − The Bias Toward Endocyclic Unsaturation in 3-Alkyl- and 3-Amino-2H-azirines: A Theoretical and Experimental Study. European J Org Chem 2002. [DOI: 10.1002/1099-0690(200206)2002:11<1750::aid-ejoc1750>3.0.co;2-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Abstract
Five monocyclic 4-benzoyl-4-phenyl-beta-lactam derivatives in carbon tetrachloride solutions were studied by FTIR spectroscopy. The Fourier self-deconvolution method was applied to enhance the resolution of the FTIR spectra. The calculated spectra of these five compounds, which were obtained by quantum mechanical methods, were compared with FTIR data. A complete assignment of the vibrational frequencies in the 4000-400 cm(-1) range was made. Several vibrations were selected as being useful to characterize the beta-lactam ring. Substituents on N1 (p-methoxyphenyl) and C3 (methyl, phenyl, maleimidyl, and phthalimidyl) on the beta-lactam ring increase the amide resonance and the planarity of the ring. The optimized geometry along with the total electric charges on the four atoms of the ring support an antibiotic action mechanism by a nucleophilic attack of the enzymes on the carbonyl carbon atom of the beta-lactam ring.
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Affiliation(s)
- M Gil
- Departamento de Química Física I, Universidad Complutense, E-28040 Madrid, Spain.
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Harrison AG, Csizmadia IG, Tang TH, Tu YP. Reaction competition in the fragmentation of protonated dipeptides. JOURNAL OF MASS SPECTROMETRY : JMS 2000; 35:683-688. [PMID: 10862119 DOI: 10.1002/1096-9888(200006)35:6<683::aid-jms994>3.0.co;2-d] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A major low-energy fragmentation reaction of many protonated dipeptides involves cleavage of the amide bond resulting in formation of either the y(1)" ion or the a(1) ion. For a series of protonated dipeptides H-Val-Xxx-OH it is observed that log(y(1)"/a(1)) is a linear function of the proton affinity of the variable C-terminal amino acid. For the series of protonated dipeptides H-Xxx-Phe-OH log(a(1)/y(1)") gives a poor correlation with the proton affinity or gas-phase basicity of H-Xxx-OH. However, a good limited correlation of log(a(1)/y(1)") with the Taft-Topsom sigma(alpha) for the alkyl group is observed when Xxx is an aliphatic amino acid. It is proposed that fragmentation occurs by initial formation of a proton-bound complex of an aziridinone and an amino acid which may fragment to form either a protonated amino acid (y(1)") or an N-protonated aziridinone with the corresponding neutrals being an aziridinone and an amino acid. Ab initio calculations show that the N-protonated aziridinone is unstable and fragments by loss of CO to form the a(1) immonium ion. However, the proton-bound complex of an aziridinone and an amine base is a stable species which exists in a potential well. Copyright 2000 John Wiley & Sons, Ltd.
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Affiliation(s)
- AG Harrison
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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O'Hair RA, Reid GE. The search for stable gas phase b(1) ions derived from aliphatic amino acids: a combined experimental and ab initio study. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2000; 14:1220-1225. [PMID: 10918371 DOI: 10.1002/1097-0231(20000730)14:14<1220::aid-rcm13>3.0.co;2-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Several previous studies have shown that b(1) ions (formally acylium ions, H(2)NCHRCO(+)) derived from protonated aliphatic amino acids are unstable in the gas phase, fragmenting via decarbonylation to form a(1) ions (iminium ions, H(2)N = CHR(+)). Herein we examine the fragmentation reactions of ten potential b(1) ion precursors to determine whether stable aliphatic b(1) ions can be formed in the gas phase. Of all the systems studied, only the aziridine b(1) ion and the dehydroalanine b(1) ion were found to be stable. These experimental results are entirely consistent with ab initio calculations (at the MP2(full)/6-311G** level) which indicate that while the loss of CO from the b(1) ion of glycine is barrierless and exoethermic, the related losses from the b(1) ions of aziridine and dehydroalanine have significant barriers (29.5 and 16.2 kcal mol(-1), respectively) and are endothermic overall.
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Affiliation(s)
- R A O'Hair
- School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia.
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Tantillo DJ, Houk KN, Hoffman RV, Tao J. Origins of Regio- and Stereoselectivity in Acid-Promoted Reactions of α-Lactams. J Org Chem 1999. [DOI: 10.1021/jo981734l] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Resonance in amides. Comparison of ab initio and semiempirical methodologies in the description of acetamide. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s0166-1280(96)04886-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Roux MV, Jiménez P, Dávalos JZ, Castaño O, Molina MT, Notario R, Herreros M, Abboud JLM. The First Direct Experimental Determination of Strain in Neutral and Protonated 2-Azetidinone. J Am Chem Soc 1996. [DOI: 10.1021/ja962792w] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. V. Roux
- Contribution from the Instituto de Química Física “Rocasolano”, C.S.I.C., c/Serrano 119, E-28006 Madrid, Spain, Departamento de Química Física, Universidad de Alcalá de Henares, E-28871 Alcalá de Henares (Madrid), Spain, and Instituto de Química Médica, C.S.I.C., c/Juan de la Cierva 3, E-28006 Madrid, Spain
| | - P. Jiménez
- Contribution from the Instituto de Química Física “Rocasolano”, C.S.I.C., c/Serrano 119, E-28006 Madrid, Spain, Departamento de Química Física, Universidad de Alcalá de Henares, E-28871 Alcalá de Henares (Madrid), Spain, and Instituto de Química Médica, C.S.I.C., c/Juan de la Cierva 3, E-28006 Madrid, Spain
| | - J. Z. Dávalos
- Contribution from the Instituto de Química Física “Rocasolano”, C.S.I.C., c/Serrano 119, E-28006 Madrid, Spain, Departamento de Química Física, Universidad de Alcalá de Henares, E-28871 Alcalá de Henares (Madrid), Spain, and Instituto de Química Médica, C.S.I.C., c/Juan de la Cierva 3, E-28006 Madrid, Spain
| | - O. Castaño
- Contribution from the Instituto de Química Física “Rocasolano”, C.S.I.C., c/Serrano 119, E-28006 Madrid, Spain, Departamento de Química Física, Universidad de Alcalá de Henares, E-28871 Alcalá de Henares (Madrid), Spain, and Instituto de Química Médica, C.S.I.C., c/Juan de la Cierva 3, E-28006 Madrid, Spain
| | - M. T. Molina
- Contribution from the Instituto de Química Física “Rocasolano”, C.S.I.C., c/Serrano 119, E-28006 Madrid, Spain, Departamento de Química Física, Universidad de Alcalá de Henares, E-28871 Alcalá de Henares (Madrid), Spain, and Instituto de Química Médica, C.S.I.C., c/Juan de la Cierva 3, E-28006 Madrid, Spain
| | - R. Notario
- Contribution from the Instituto de Química Física “Rocasolano”, C.S.I.C., c/Serrano 119, E-28006 Madrid, Spain, Departamento de Química Física, Universidad de Alcalá de Henares, E-28871 Alcalá de Henares (Madrid), Spain, and Instituto de Química Médica, C.S.I.C., c/Juan de la Cierva 3, E-28006 Madrid, Spain
| | - M. Herreros
- Contribution from the Instituto de Química Física “Rocasolano”, C.S.I.C., c/Serrano 119, E-28006 Madrid, Spain, Departamento de Química Física, Universidad de Alcalá de Henares, E-28871 Alcalá de Henares (Madrid), Spain, and Instituto de Química Médica, C.S.I.C., c/Juan de la Cierva 3, E-28006 Madrid, Spain
| | - J.-L. M. Abboud
- Contribution from the Instituto de Química Física “Rocasolano”, C.S.I.C., c/Serrano 119, E-28006 Madrid, Spain, Departamento de Química Física, Universidad de Alcalá de Henares, E-28871 Alcalá de Henares (Madrid), Spain, and Instituto de Química Médica, C.S.I.C., c/Juan de la Cierva 3, E-28006 Madrid, Spain
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Bordejé MC, Mó O, Yáñez M. Binding energies of metal monocations to Β-lactones and Β-lactams. A theoretical study of cyclization effects. Struct Chem 1996. [DOI: 10.1007/bf02275157] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Greenberg A, Moore DT, DuBois TD. Small and Medium-Sized Bridgehead Bicyclic Lactams: A Systematic ab Initio Molecular Orbital Study. J Am Chem Soc 1996. [DOI: 10.1021/ja960294h] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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