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Bejarano CA, Díaz JE, Cifuentes-López A, López LV, Jaramillo-Gómez LM, Buendia-Atencio C, Lorett Velásquez VP, Mejía SM, Loaiza AE. Experimental and theoretical study of the mechanism and rate constants of the sequential 5- exo-trig spirocyclization involving vinyl, aryl and N-alkoxyaminyl radicals. Org Biomol Chem 2022; 20:4141-4154. [PMID: 35521783 DOI: 10.1039/d2ob00387b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this research the sequential generation and cyclization of N-alkoxyaminyl radicals to produce 1-azaspiro[4.4]nonane, a prominent scaffold in organic and medicinal chemistry, was studied. Competition experiments in benzene at 80 °C with brominated oxime ethers using Bu3SnH as chain transfer and AIBN as the initiator generated vinyl or aryl radicals which were captured by oxime ethers, allowing approximate 5-exo-trig cyclization constants at 4.6 × 108 s-1 and 9.9 × 108 s-1 respectively to be established. Similar results were obtained by kinetic studies using the transition state theory (TST) from ab initio calculations with density functional theory (DFT) using the M06-2X, B3LYP, mPW1PW91 and TPSSh functionals in combination with the 6-311+G(d, p) basis set. Additionally, it was found that the 5-exo-trig cyclization of the N-alkoxyaminyl radical onto CC double bonds is a reversible process whose constants were determined to be in the range of 6.2 × 100 s-1 and 3.5 × 106 s-1 at 80 °C, depending on the nature of the substituents. The calculation of the radical stabilization energy (RSE) shows that the N-alkoxyaminyl radical is a very stable species and its reactivity in the addition on alkenes is governed by its nucleophilic character and the stability of the carbon-centered radical formed after cyclization. The reduction constant of the N-alkoxyaminyl radical with Bu3SnH in the gas phase at 80 °C was also estimated to be 3.4 × 100 M-1 s-1 through computational calculations. This information facilitates the rational planning of cascades and other methodologies applied to the construction of carbocyclic and aza-heterocyclic compounds.
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Affiliation(s)
- Carlos A Bejarano
- Departamento de Química, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá 11001000, Colombia. .,Departamento de Química, Facultad de Ciencias, Universidad Antonio Nariño, Bogotá 110231, Colombia
| | - John E Díaz
- Departamento de Química, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá 11001000, Colombia.
| | | | - Lina V López
- Departamento de Química, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá 11001000, Colombia.
| | - Luz M Jaramillo-Gómez
- Departamento de Química, Facultad de Ciencias, Universidad del Valle, Cali 760032, Colombia
| | - Cristian Buendia-Atencio
- Departamento de Química, Facultad de Ciencias, Universidad Antonio Nariño, Bogotá 110231, Colombia
| | | | - Sol M Mejía
- Departamento de Química, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá 11001000, Colombia.
| | - Alix E Loaiza
- Departamento de Química, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá 11001000, Colombia.
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Density functional theory assessment of transannular N⋯Y interactions in some medium-sized heterocycles. COMPUT THEOR CHEM 2022. [DOI: 10.1016/j.comptc.2021.113543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Prasad VK, Khalilian MH, Otero-de-la-Roza A, DiLabio GA. BSE49, a diverse, high-quality benchmark dataset of separation energies of chemical bonds. Sci Data 2021; 8:300. [PMID: 34815431 PMCID: PMC8611007 DOI: 10.1038/s41597-021-01088-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 11/01/2021] [Indexed: 01/23/2023] Open
Abstract
We present an extensive and diverse dataset of bond separation energies associated with the homolytic cleavage of covalently bonded molecules (A-B) into their corresponding radical fragments (A. and B.). Our dataset contains two different classifications of model structures referred to as "Existing" (molecules with associated experimental data) and "Hypothetical" (molecules with no associated experimental data). In total, the dataset consists of 4502 datapoints (1969 datapoints from the Existing and 2533 datapoints from the Hypothetical classes). The dataset covers 49 unique X-Y type single bonds (except H-H, H-F, and H-Cl), where X and Y are H, B, C, N, O, F, Si, P, S, and Cl atoms. All the reference data was calculated at the (RO)CBS-QB3 level of theory. The reference bond separation energies are non-relativistic ground-state energy differences and contain no zero-point energy corrections. This new dataset of bond separation energies (BSE49) is presented as a high-quality reference dataset for assessing and developing computational chemistry methods.
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Affiliation(s)
- Viki Kumar Prasad
- Department of Chemistry, University of British Columbia, Kelowna, British Columbia, V1V 1V7, Canada
| | - M Hossein Khalilian
- Department of Chemistry, University of British Columbia, Kelowna, British Columbia, V1V 1V7, Canada
| | - Alberto Otero-de-la-Roza
- Departamento de Química Física y Analítica, Facultad de Química, Universidad de Oviedo, MALTA Consolider Team, E-33006, Oviedo, Spain
| | - Gino A DiLabio
- Department of Chemistry, University of British Columbia, Kelowna, British Columbia, V1V 1V7, Canada.
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Povie G, Suravarapu SR, Bircher MP, Mojzes MM, Rieder S, Renaud P. Radical chain repair: The hydroalkylation of polysubstituted unactivated alkenes. SCIENCE ADVANCES 2018; 4:eaat6031. [PMID: 30035230 PMCID: PMC6054511 DOI: 10.1126/sciadv.aat6031] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 06/13/2018] [Indexed: 06/08/2023]
Abstract
The concept of repair is widely used by nature to heal molecules such as proteins, lipids, sugars, and DNA that are damaged by hydrogen atom abstraction resulting from oxidative stress. We show that this strategy, rather undocumented in the field of synthetic organic chemistry, can be used in a radical chain reaction to enable notoriously intractable transformations. By overcoming the radical chain inhibitor properties of substituted alkenes, the radical-mediated hydroalkylation of mono-, di-, tri-, and even tetrasubstituted unactivated olefins could be performed under mild conditions. With a remarkable functional group tolerance, this reaction provides a general coupling method for the derivatization of olefin-containing natural products.
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Belhadj Slimen I, Najar T, Abderrabba M. Chemical and Antioxidant Properties of Betalains. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2017; 65:675-689. [PMID: 28098998 DOI: 10.1021/acs.jafc.6b04208] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Betalains are vacuolar pigments composed of a nitrogenous core structure, betalamic acid. Betalamic acid condenses with imino compounds (cyclo-DOPA/its glucosyl derivates) or amino acids/derivates to form violet betacyanins and yellow betaxanthins. These pigments have gained the curiosity of scientific researchers in recent decades. Their importance was increased not only by market orientation toward natural colorants and antioxidants but also by their safety and health promoting properties. To date, about 78 betalains have been identified from plants of about 17 families. In this review, all of the identified pigments are presented, followed by a comprehensive discussion of their structure-activity relationship.
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Affiliation(s)
- Imen Belhadj Slimen
- Department of Animal, Food and Halieutic Resources, National Agronomic Institute of Tunisia , 43 Avenue Charles Nicolle, 1082 Tunis, Tunisia
- Laboratory of Materials, Molecules and Applications, Preparatory Institute for Scientific and Technical Studies , BP 51, 2070 La Marsa, Tunis, Tunisia
| | - Taha Najar
- Department of Animal, Food and Halieutic Resources, National Agronomic Institute of Tunisia , 43 Avenue Charles Nicolle, 1082 Tunis, Tunisia
- Laboratory of Materials, Molecules and Applications, Preparatory Institute for Scientific and Technical Studies , BP 51, 2070 La Marsa, Tunis, Tunisia
| | - Manef Abderrabba
- Laboratory of Materials, Molecules and Applications, Preparatory Institute for Scientific and Technical Studies , BP 51, 2070 La Marsa, Tunis, Tunisia
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Degirmenci I, Coote ML. UNDERSTANDING THE BEHAVIOUR OF SULPHUR-CENTRED RADICALS DURING POLYMER SELF-HEALING. JOURNAL OF THE TURKISH CHEMICAL SOCIETY, SECTION A: CHEMISTRY 2016. [DOI: 10.18596/jotcsa.287305] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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Degirmenci I, Coote ML. Effect of Substituents on the Stability of Sulfur-Centered Radicals. J Phys Chem A 2016; 120:7398-403. [DOI: 10.1021/acs.jpca.6b08223] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Isa Degirmenci
- Chemical
Engineering Department, Ondokuz Mayıs University, Samsun 55139, Turkey
- ARC
Centre of Excellence for Electromaterials Science, Research School
of Chemistry, The Australian National University, Canberra, ACT 2601, Australia
| | - Michelle L. Coote
- ARC
Centre of Excellence for Electromaterials Science, Research School
of Chemistry, The Australian National University, Canberra, ACT 2601, Australia
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