Dynamic effects in the didehydro‐Diels‐Alder (DDDA) reaction of enyne‐ketoenes: 50% stepwise bond formation in spite of concerted transition state†. (12th July 2017)

• Record Type: Journal Article
• Authors: Rana, Anup; Paul, Indrajit; Schmittel, Michael
• Other Names: Ihmels Heiko guestEditor.; Linker Torsten guestEditor.; Trofimov Aleksei guestEditor.
• Is Part Of: Journal of physical organic chemistry. Volume 30:Number 9(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-07-12
• Subjects: Chemistry, Physical organic -- Periodicals; 547.1
• DOI: 10.1002/poc.3732
• Languages: English
• ISSNs: 0894-3230

Abstract

Abstract: The C 2 ─C 6 /Diels‐Alder cyclization of enyne‐ketoene1 was studied by experiments, theoretical calculations, and dynamic trajectory computations. The failure to trap possible intermediate(s), indicates a concerted reaction mechanism. A detailed search for stationary points revealed a concerted mechanism and surprisingly a diradical intermediate with no direct connection to the enyne‐ketoene1 . To probe the accessibility of this intermediate quasiclassical trajectories were initiated from the concerted transition state structure. Notably, 36% of the trajectories reach the product zone directly and 5% arrive at the product via the intermediate diradical. Additionally, 31% of the trajectories go to the intermediate zone and stay there within the simulation time limit. Abstract : The mechanism of the didehydro‐Diels‐Alder reaction of ( E )‐3‐phenyl‐1‐(2‐(phenylethynyl)phenyl)prop‐2‐en‐1‐one is investigated experimentally as well as computationally. As all experiments to trap an intermediate failed, a detailed computational study was instigated. Molecular dynamics simulation revealed that the concerted transition state acts as a common bottleneck for both the concerted and stepwise paths.