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Evidence for Triplet Sensitization in the Visible-Light-Induced [2+2]?Photocycloaddition of Eniminium Ions.

ABSTRACT: ?niminium ions were prepared from the corresponding ?,?-unsaturated carbonyl compounds (enones and enals), and were found to be promoted to their respective triplet states by energy transfer. The photoexcited intermediates underwent intra- or intermolecular [2+2] photocycloaddition in good yields (50-78?%) upon irradiation at ?=433?nm or ?=457?nm. Iridium or ruthenium complexes with a sufficiently high triplet energy were identified as efficient catalysts (2.5?mol?% catalyst loading) for the reaction. The intermolecular [2+2] photocycloaddition of an eniminium ion derived from a chiral secondary amine proceeded with high enantioselectivity (88?% ee).

SUBMITTER: Hormann FM

PROVIDER: S-EPMC5768022 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Evidence for Triplet Sensitization in the Visible-Light-Induced [2+2] Photocycloaddition of Eniminium Ions.

Hörmann Fabian M FM Chung Tim S TS Rodriguez Elsa E Jakob Matthias M Bach Thorsten T

Angewandte Chemie (International ed. in English) 20171213 3

Εniminium ions were prepared from the corresponding α,β-unsaturated carbonyl compounds (enones and enals), and were found to be promoted to their respective triplet states by energy transfer. The photoexcited intermediates underwent intra- or intermolecular [2+2] photocycloaddition in good yields (50-78 %) upon irradiation at λ=433 nm or λ=457 nm. Iridium or ruthenium complexes with a sufficiently high triplet energy were identified as efficient catalysts (2.5 mol % catalyst loading) for the rea ...[more]

PMID: 29178574

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