Volume 241, 2023

Photomechanochemical control over stereoselectivity in the [2 + 2] photodimerization of acenaphthylene

Abstract

Tuning solubility and mechanical activation alters the stereoselectivity of the [2 + 2] photochemical cycloaddition of acenaphthylene. Photomechanochemical conditions produce the syn cyclobutane, whereas the solid-state reaction in the absence of mechanical activation provides the anti. When the photochemical dimerization occurs in a solubilizing organic solvent, there is no selectivity. Dimerization in H2O, in which acenaphthylene is insoluble, provides the anti product. DFT calculations reveal that insoluble and solid-state reactions proceed via a covalently bonded excimer, which drives anti selectivity. Alternatively, the noncovalently bound syn conformer is more mechanosusceptible than the anti, meaning it experiences greater destabilization, thereby producing the syn product under photomechanochemical conditions. Cyclobutanes are important components of biologically active natural products and organic materials, and we demonstrate stereoselective methods for obtaining syn or anti cyclobutanes under mild conditions and without organic solvents. With this work, we validate photomechanochemistry as a viable new direction for the preparation of complex organic scaffolds.

Graphical abstract: Photomechanochemical control over stereoselectivity in the [2 + 2] photodimerization of acenaphthylene

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
02 6 2022
Accepted
28 6 2022
First published
29 6 2022

Faraday Discuss., 2023,241, 266-277

Author version available

Photomechanochemical control over stereoselectivity in the [2 + 2] photodimerization of acenaphthylene

S. Biswas, S. Banerjee, M. A. Shlain, A. A. Bardin, R. V. Ulijn, B. L. Nannenga, A. M. Rappe and A. B. Braunschweig, Faraday Discuss., 2023, 241, 266 DOI: 10.1039/D2FD00122E

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