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DOI: 10.1055/a-2601-5311
Enantioselective Photochemical Generation of a cis-Cycloheptenone Isomer
Enantioselective Photochemical Generation of a Short-Lived, Twisted Cycloheptenone Isomer: Catalytic Formation, Detection, and Consecutive Chemistry.
Angew. Chem. Int. Ed. 2025;
DOI: 10.1002/anie.202501433
Significance
Bach and co-workers demonstrate the first enantioselective photoisomerization of a cis-cycloheptenone via triplet energy transfer using a bifunctional chiral phosphoric acid (CPA) photocatalyst. The short-lived trans isomer was directly detected by time-resolved IR spectroscopy and trapped in stereospecific Diels–Alder reactions. Combined experimental and computational analysis reveals that conformer-selective binding and excited-state dynamics enable chirality transfer. The work establishes a general concept for asymmetric photocatalysis based on dual-function CPA design.
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Comment
This study demonstrates enantioselective triplet energy transfer using a CPA-based photocatalyst that binds the substrate in a chiral environment. The transient trans isomer is directly observed and stereospecifically trapped in Diels–Alder reactions. Despite only moderate enantioselectivity, the approach provides a powerful concept for asymmetric photochemical catalysis. The mechanism of enantioselectivity is still under discussion; a heterodimeric complex between the CPA and the substrate might participate directly in the stereodetermining step, possibly involving excitation of the complex itself (see Angew. Chem. Int. Ed. 2014, 53, 7063).
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Publication History
Article published online:
23 June 2025
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