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Francisco CB, Fernandes CDS, Franco Dourado F, Gauze GDF, Rittner R, Prosser RS, Basso EA. Conformational Landscape of α-Halopropiophenones Determined by nJC-H NMR Reveals Unexpected Patterns and Geometric Constraints. J Phys Chem A 2024; 128:1566-1575. [PMID: 38412415 DOI: 10.1021/acs.jpca.3c06934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
The conformational features of α-halopropiophenones were investigated to understand the influence of α-halogens on conformation through hyperconjugative interactions, electrostatics, and steric factors. Using NMR, C-H scalar coupling constants were measured in different solvents, revealing a pattern in the conformational equilibria, which we validated by computational means. This behavior arises largely from hyperconjugative effects with the exception of the fluoro-derivatives, which are also influenced by steric and electrostatic interactions. In all cases, the contribution to hyperconjugation of the α-halo ketones is driven by the oxygen lone pair (rather than the C-X bond), which donates electron density to the adjacent C-C bonds. Additionally, C-Cα bond rotation generates distortions in the side chain, responsible for destabilization, thus affecting system conjugation. These structural features identified for the α-halo ketones are also reflected in their reactivity, which is distinct from that expected for nucleophilic addition.
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Affiliation(s)
- Camila Botin Francisco
- Department of Chemistry, State University of Maringá, 5790, Maringá 87020-900, Brazil
- Department of Chemistry, University of Toronto, 3359, Mississauga L5L-1C6, Canada
| | | | | | | | - Roberto Rittner
- Chemistry Institute, University of Campinas, 6154, Campinas 13083-970, Brazil
| | - Robert Scott Prosser
- Department of Chemistry, University of Toronto, 3359, Mississauga L5L-1C6, Canada
| | - Ernani Abicht Basso
- Department of Chemistry, State University of Maringá, 5790, Maringá 87020-900, Brazil
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Pattison G. Conformational preferences of α-fluoroketones may influence their reactivity. Beilstein J Org Chem 2017; 13:2915-2921. [PMID: 29564019 PMCID: PMC5753061 DOI: 10.3762/bjoc.13.284] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 12/12/2017] [Indexed: 11/23/2022] Open
Abstract
Fluorine has been shown in many cases to impart specific and predictable effects on molecular conformation. Here it is shown that these conformational effects may have an influence on reactivity through studying the relative reactivity of various α-halogenated ketones towards borohydride reduction. These results demonstrate that the α-fluoro ketones are in fact a little less reactive than the corresponding α-chloro and α-bromo derivatives. It is suggested, supported by computation, that this effect is due to reactive conformations in which the C–X bond is orthogonal to the carbonyl group for good orbital overlap being disfavoured in the case of fluoro ketones.
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Affiliation(s)
- Graham Pattison
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
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Fiorin BC, Basso EA, Tormena CF, Rittner R, Abraham RJ. Theoretical and Experimental Investigation on the Rotational Isomerism in α-Fluoroacetophenones. J Phys Chem A 2009; 113:2906-13. [DOI: 10.1021/jp808048s] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Barbara C. Fiorin
- Departamento de Química, Universidade Estadual de Ponta Grossa/UEPG, Av. General Carlos Cavalcanti 4748, 84030-900—Ponta Grossa, PR, Brazil, Departamento de Química, Universidade Estadual de Maringá/UEM, Av. Colombo 5790, 87020-900—Maringá, PR, Brazil, Physical Organic Chemistry Laboratory, Chemistry Institute, State University of Campinas/UNICAMP, Caixa Postal 6154, 13083-862—Campinas, SP, Brazil, and Chemistry Department, University of Liverpool, P. O. Box 147, Liverpool L69 3BX, United Kingdom
| | - Ernani A. Basso
- Departamento de Química, Universidade Estadual de Ponta Grossa/UEPG, Av. General Carlos Cavalcanti 4748, 84030-900—Ponta Grossa, PR, Brazil, Departamento de Química, Universidade Estadual de Maringá/UEM, Av. Colombo 5790, 87020-900—Maringá, PR, Brazil, Physical Organic Chemistry Laboratory, Chemistry Institute, State University of Campinas/UNICAMP, Caixa Postal 6154, 13083-862—Campinas, SP, Brazil, and Chemistry Department, University of Liverpool, P. O. Box 147, Liverpool L69 3BX, United Kingdom
| | - Cláudio F. Tormena
- Departamento de Química, Universidade Estadual de Ponta Grossa/UEPG, Av. General Carlos Cavalcanti 4748, 84030-900—Ponta Grossa, PR, Brazil, Departamento de Química, Universidade Estadual de Maringá/UEM, Av. Colombo 5790, 87020-900—Maringá, PR, Brazil, Physical Organic Chemistry Laboratory, Chemistry Institute, State University of Campinas/UNICAMP, Caixa Postal 6154, 13083-862—Campinas, SP, Brazil, and Chemistry Department, University of Liverpool, P. O. Box 147, Liverpool L69 3BX, United Kingdom
| | - Roberto Rittner
- Departamento de Química, Universidade Estadual de Ponta Grossa/UEPG, Av. General Carlos Cavalcanti 4748, 84030-900—Ponta Grossa, PR, Brazil, Departamento de Química, Universidade Estadual de Maringá/UEM, Av. Colombo 5790, 87020-900—Maringá, PR, Brazil, Physical Organic Chemistry Laboratory, Chemistry Institute, State University of Campinas/UNICAMP, Caixa Postal 6154, 13083-862—Campinas, SP, Brazil, and Chemistry Department, University of Liverpool, P. O. Box 147, Liverpool L69 3BX, United Kingdom
| | - Raymond J. Abraham
- Departamento de Química, Universidade Estadual de Ponta Grossa/UEPG, Av. General Carlos Cavalcanti 4748, 84030-900—Ponta Grossa, PR, Brazil, Departamento de Química, Universidade Estadual de Maringá/UEM, Av. Colombo 5790, 87020-900—Maringá, PR, Brazil, Physical Organic Chemistry Laboratory, Chemistry Institute, State University of Campinas/UNICAMP, Caixa Postal 6154, 13083-862—Campinas, SP, Brazil, and Chemistry Department, University of Liverpool, P. O. Box 147, Liverpool L69 3BX, United Kingdom
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Olivato PR, Nanartonis R, Lopes JCD, Hase Y. CONFORMATIONAL AND ELECTRONIC INTERACTION STUDIES OF α-SUBSTITUTED CARBONYL COMPOUNDS. XII. S-ETHYL α-HETERO-SUBSTITUTED THIOACETATES. PHOSPHORUS SULFUR 2006. [DOI: 10.1080/10426509208034502] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Paulo R. Olivato
- a Instituto de Química da Universidade de São Paulo , Caixa Postal 20.780, 01498 , São Paulo , S.P. , Brazil
| | - R. Nanartonis
- a Instituto de Química da Universidade de São Paulo , Caixa Postal 20.780, 01498 , São Paulo , S.P. , Brazil
| | - J. C. D. Lopes
- a Instituto de Química da Universidade de São Paulo , Caixa Postal 20.780, 01498 , São Paulo , S.P. , Brazil
| | - Yoshiyuki Hase
- b Instituto de Química, Universidade Estadual de Campinas , Caixa Postal 6154, 13081 , Campinas , S.P. , Brazil
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Olivato PR, Guerrero SA. CONFORMATIONAL AND ELECTRONIC INTERACTION STUDIES OF α-SUBSTITUTED CARBONYL COMPOUNDS. XI. ω-(p-PHENYLTHIO)-p-SUBSTITUTED ACETOPHENONES. PHOSPHORUS SULFUR 2006. [DOI: 10.1080/10426509208038350] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Paulo R. Olivato
- a Institute de Química , Universidade de sāo Paulo , Caixa Postal 20.780, 01.498 , sāo Paulo , S.P. , Brazil
| | - Sandra A. Guerrero
- a Institute de Química , Universidade de sāo Paulo , Caixa Postal 20.780, 01.498 , sāo Paulo , S.P. , Brazil
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