Diastereoselectivity in Photochemistry - CNRS - Centre national de la recherche scientifique
Chapitre D'ouvrage Année : 2023

Diastereoselectivity in Photochemistry

Résumé

Diastereoselective photochemical reactions play an important role for asymmetric synthesis, for example for the synthesis of natural or biologically active compounds. Chirality is either induced by a chiral auxiliary or by a chiral centers already present in the substrates. In the first case, the source of chirality is removed during the ongoing multistep synthesis. In the second case, the chirality source is conserved in the target compound. In the present chapter examples of the [2+2] photocycloaddition of carbonyl compounds with alkenes (Paternò-Büchi reaction), between α,β-unsaturated carbonyl compounds and alkenes as well as between two alkenes are discussed. Typical diastereoselective photocycloaddition reaction with aromatic compounds are reported. Currently, photoinduced radical reactions are intensively investigated and photoredox or more generally photocatalysis play a key role. In such reactions neutral radicals and radical ions are typical intermediates. Under photochemical conditions, tautomeric equilibria significantly change. Due to this fact, interesting diastereoselective reactions have been reported. Electrocyclization has often been applied to the synthesis of heterocyclic compounds. Photochemical rearrangements provide convenient accesses to complex polycyclic compounds. The diastereoselectivity is significantly increased when the corresponding reactions are carried out under confinement conditions, for example with inclusion complexes. Photooxygenation with singlet oxygen is a very convenient oxidation method. Generally, such reactions are highly regio stereo and chemoselective.
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Dates et versions

hal-04194008 , version 1 (01-09-2023)

Identifiants

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Norbert Hoffmann. Diastereoselectivity in Photochemistry. Louis Fensterbank; Cyril Ollivier. Reference Module in Chemistry, Molecular Sciences and Chemical Engineering; Comprehensive Chirality, 2nd edition, Elsevier, 2023, ⟨10.1016/B978-0-32-390644-9.00113-X⟩. ⟨hal-04194008⟩
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