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Martins FA, de Azevedo Santos L, Rodrigues Silva D, Fonseca Guerra C, Bickelhaupt FM, Freitas MP. Iodine Gauche Effect Induced by an Intramolecular Hydrogen Bond. J Org Chem 2022; 87:11625-11633. [PMID: 35984736 DOI: 10.1021/acs.joc.2c01258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The gauche conformer in 1-X,2-Y-disubstituted ethanes, that is, the staggered orientation in which X and Y are in closer contact, is only favored for relatively small substituents that do not give rise to large X···Y steric repulsion. For more diffuse substituents, weakly attractive orbital interactions between antiperiplanar bonds (i.e., hyperconjugation) cannot overrule the repulsive forces between X and Y. Our quantum chemical analyses of the rotational isomerism of XCH2CH2Y (X = F, OH; Y = I) at ZORA-BP86-D3(BJ)/QZ4P reveal that indeed the anti conformer is generally favored due to a less destabilizing I···F and I···O-H steric repulsion. The only case when the gauche conformer is preferred is when the hydroxyl hydrogen is oriented toward the iodine atom in the 2-iodoethanol. This is because of the significantly stabilizing covalent component of the I···H-O intramolecular hydrogen bond. Therefore, we show that strong intramolecular interactions can overcome the steric repulsion between bulky substituents in 1,2-disubstituted ethanes and cause the gauche effect. Our quantum chemical computations have guided nuclear magnetic resonance experiments that confirm the increase in the gauche population as X goes from F to OH.
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Affiliation(s)
- Francisco A Martins
- Department of Chemistry, Institute of Natural Sciences, Federal University of Lavras, 37200-900 Lavras, Minas Gerais, Brazil
| | - Lucas de Azevedo Santos
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Daniela Rodrigues Silva
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Célia Fonseca Guerra
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - F Matthias Bickelhaupt
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.,Institute for Molecules and Materials (IMM), Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Matheus P Freitas
- Department of Chemistry, Institute of Natural Sciences, Federal University of Lavras, 37200-900 Lavras, Minas Gerais, Brazil
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Musio R, Sciacovelli O. Conformational studies on 2-substituted ethanesulfonates in aqueous solution by 1H NMR spectroscopy and DFT calculations. J Mol Struct 2009. [DOI: 10.1016/j.molstruc.2009.06.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Perrin CL, Lau JS, Kim YJ, Karri P, Moore C, Rheingold AL. Asymmetry of the “Strongest” OHO Hydrogen Bond, in the Monoanion of (±)-α,α′-Di-tert-butylsuccinate. J Am Chem Soc 2009; 131:13548-54. [DOI: 10.1021/ja905806h] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Charles L. Perrin
- Department of Chemistry, University of California—San Diego, La Jolla, California 92093-0358
| | - Jonathan S. Lau
- Department of Chemistry, University of California—San Diego, La Jolla, California 92093-0358
| | - Yeong-Joon Kim
- Department of Chemistry, University of California—San Diego, La Jolla, California 92093-0358
| | - Phaneendrasai Karri
- Department of Chemistry, University of California—San Diego, La Jolla, California 92093-0358
| | - Curtis Moore
- Department of Chemistry, University of California—San Diego, La Jolla, California 92093-0358
| | - Arnold L. Rheingold
- Department of Chemistry, University of California—San Diego, La Jolla, California 92093-0358
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Nkansah RA, Liu Y, Alley OJ, Gerken JB, Drake MD, Roberts JD. Conformational preferences of 3-(dimethylazinoyl)propanoic acid as a function of pH and solvent; intermolecular versus intramolecular hydrogen bonding. J Org Chem 2009; 74:2344-9. [PMID: 19245202 DOI: 10.1021/jo802488k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The conformational equilibrium of 3-(dimethylazinoyl)propanoic acid (DMAPA, azinoyl = N(+)(O(-)) has a weak pH-dependence in D(2)O, with a slight preference for trans in alkaline solutions. The acid ionization constants of the protonated amine oxide and carboxylic functional groups as determined by NMR spectroscopy were 7.9 x 10(-4) and 6.3 x 10(-6), respectively. The corresponding value of K(1)/K(2) of 1.3 x 10(2) is not deemed large enough to provide experimental NMR evidence for a significant degree of intramolecular hydrogen bonding in D(2)O. Conformational preferences of DMAPA are mostly close to statistical (gauche/trans = 2/1) in other protic solvents, e.g., alcohols. However, the un-ionized form of DMAPA appears to be strongly intramolecularly hydrogen-bonded and gauche in aprotic solvents.
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Affiliation(s)
- Richard A Nkansah
- Crellin Laboratory of Chemistry, California Institute of Technology, Pasadena, California 91125, USA
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