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arXiv · 2107.13858

Conformer-specific polar cycloaddition of dibromobutadiene with trapped propene ions

Ardita Kilaj·Jia Wang·Patrik Stranak·Max Schwilk·Uxia Rivero·Lei Xu·O. Anatole von Lilienfeld·Jochen Küpper·Stefan Willitsch
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Abstract

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 a new experimental approach to explore the mechanistic details 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.

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Ardita Kilaj, Jia Wang, Patrik Stranak, Max Schwilk, Uxia Rivero, Lei Xu, O. Anatole von Lilienfeld, Jochen Küpper, Stefan Willitsch. 2021-07-29. Conformer-specific polar cycloaddition of dibromobutadiene with trapped propene ions. https://doi.org/10.1038/s41467-021-26309-5

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