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Quantum-chemistry-aided identification, synthesis and experimental validation of model systems for conformationally controlled reaction studies: separation of the conformers of 2,3-dibromobuta-1,3-diene in the gas phase

Kilaj, Ardita and Gao, Hong and Tahchieva, Diana and Ramakrishnan, Raghunathan and Bachmann, Daniel and Gillingham, Dennis and von Lilienfeld, O. Anatole and Kuepper, Jochen and Willitsch, Stefan. (2020) Quantum-chemistry-aided identification, synthesis and experimental validation of model systems for conformationally controlled reaction studies: separation of the conformers of 2,3-dibromobuta-1,3-diene in the gas phase. Physical Chemistry Chemical Physics, 22 (24). pp. 13431-13439.

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Abstract

The Diels-Alder cycloaddition, in which a diene reacts with a dienophile to form a cyclic compound, counts among the most important tools in organic synthesis. Achieving a precise understanding of its mechanistic details on the quantum level requires new experimental and theoretical methods. Here, we present an experimental approach that separates different diene conformers in a molecular beam as a prerequisite for the investigation of their individual cycloaddition reaction kinetics and dynamics under single-collision conditions in the gas phase. A low- and high-level quantum-chemistry-based screening of more than one hundred dienes identified 2,3-dibromobutadiene (DBB) as an optimal candidate for efficient separation of itsgaucheand s-transconformers by electrostatic deflection. A preparation method for DBB was developed which enabled the generation of dense molecular beams of this compound. The theoretical predictions of the molecular properties of DBB were validated by the successful separation of the conformers in the molecular beam. A marked difference in photofragment ion yields of the two conformers upon femtosecond-laser pulse ionization was observed, pointing at a pronounced conformer-specific fragmentation dynamics of ionized DBB. Our work sets the stage for a rigorous examination of mechanistic models of cycloaddition reactions under controlled conditions in the gas phase.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Organische Chemie (Gillingham)
UniBasel Contributors:Kilaj, Ardita and Gao, Hong and Tahchieva, Diana Nikolaeva and Ramakrishnan, Raghunathan and Bachmann, Daniel and Gillingham, Dennis and von Lilienfeld, Anatole and Willitsch, Stefan
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Royal Society of Chemistry
ISSN:1463-9076
e-ISSN:1463-9084
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
Identification Number:
Last Modified:12 Aug 2020 15:01
Deposited On:15 Jul 2020 07:35

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