• DOI:10.1038/s41467-021-26309-5
• Corpus ID: 236493775

Conformer-specific polar cycloaddition of dibromobutadiene with trapped propene ions

@article{Kilaj2021ConformerspecificPC,
  title={Conformer-specific polar cycloaddition of dibromobutadiene with trapped propene ions},
  author={Ardita Kilaj and Jia Wang and Patrik Straň{\'a}k and Max Schwilk and Ux{\'i}a Rivero and Lei Xu and O. Anatole von Lilienfeld and Jochen K{\"u}pper and Stefan Willitsch},
  journal={Nature Communications},
  year={2021},
  volume={12}
}

• Ardita Kilaj, Jia Wang, +6 authors S. Willitsch
• Published 29 July 2021
• Chemistry
• Nature Communications

Diels–Alder cycloadditions are efficient routes for the synthesis of cyclic organic compounds. There has been a long-standing discussion whether these reactions proceed via stepwise or concerted mechanisms. Here, we adopt an experimental approach to explore the mechanism of the model polar cycloaddition of 2,3-dibromo-1,3-butadiene with propene ions by probing its conformational specificities in the entrance channel under single-collision conditions in the gas phase. Combining a conformationally controlled molecular beam with trapped ions, we find that both conformers of the diene, gauche and s-trans , are reactive with capture-limited reaction rates. Aided by quantum-chemical and quantum-capture calculations, this finding is rationalised by a simultaneous competition of concerted and stepwise reaction pathways, revealing an interesting mechanistic borderline case. Identifying a concerted or stepwise mechanism in Diels–Alder reactions is experimentally challenging. Here the authors demonstrate the coexistence of both mechanisms in the reaction of 2,3-dibromobuta-1,3-diene with propene ions, using a conformationally controlled molecular beam reacting with trapped ions and ab initio computations