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Theoretical investigation of the effect of hydrogen bonding on the stereoselectivity of the Diels-Alder reaction

Taherinia, D ; Sharif University of Technology | 2021

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  1. Type of Document: Article
  2. DOI: 10.1039/d1nj01373d
  3. Publisher: Royal Society of Chemistry , 2021
  4. Abstract:
  5. In this article, we report the computational examination of the impact of hydrogen bonding (HB) on the stereoselectivity of a series of Diels-Alder (DA) reactions. Four different types of diene/dienophile couples were studied including (a) cyclopenta-2,4-dien-1-ol and heteroatom-substituted cyclopentenes, (b) substituted cyclopentadienes andN-protonated 2,5-dihydro-1H-pyrrole, (c) furan andN-protonated 5-azabicyclo[2.1.1]hex-2-ene, and (d)N-protonated cyclopenta-2,4-dien-1-amine and α,β-unsaturated carbonyl compounds. These systems were designed such that the HB can only exist in theexoreaction pathway. The optimized structures of the transition states (TSs) and products, along with the Gibbs free energies of activation and reaction were calculated in the gas phase and dichloromethane by B3LYP/6-31G++(d,p) method. It was found that theexoadduct is the most kinetically and thermodynamically favored product for all of the DA reactions mentioned above. Moreover, the role of the HB in stabilizing theexostereoisomer (and the corresponding TS) was much more pronounced for the reactions involving cationic species (cases b-d). In the end, a hypothetical synthetic method was proposed for obtainingexo-2-alkylbicyclo[2.2.1]heptanes. Our findings suggest that the HB can be employed as an effective interaction to control the stereoselectivity of DA reactions. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021
  6. Keywords:
  7. Activation energy ; Carbonyl compounds ; Dichloromethane ; Gibbs free energy ; Hydrogen ; Phase transitions ; Stereoselectivity ; Unsaturated compounds ; Cyclopentenes ; Diels-Alder reaction ; Dienophiles ; Effect of hydrogen ; Heteroatoms ; Protonated ; Substituted cyclopentadienes ; Theoretical investigations ; Transition state ; Unsaturated carbonyl compounds ; Hydrogen bonds
  8. Source: New Journal of Chemistry ; Volume 45, Issue 36 , 2021 , Pages 16760-16772 ; 11440546 (ISSN)
  9. URL: https://pubs.rsc.org/en/content/articlelanding/2021/nj/d1nj01373d