Photosensitized O2 enables intermolecular alkene cyclopropanation by active methylene compounds.
Science
; 381(6657): 545-553, 2023 Aug 04.
Article
en En
| MEDLINE
| ID: mdl-37535731
ABSTRACT
Cyclopropanes are key features in many preclinical, clinical, and commercial drugs, as well as natural products. The most prolific technique for their synthesis is the metal-catalyzed reaction of an alkene with a diazoalkane, a highly energetic reagent requiring stringent safety precautions. Discovery of alternative innocuous reagents remains an ongoing challenge. Herein, we report a simple photoredox-catalyzed intermolecular cyclopropanation of unactivated alkenes with active methylene compounds. The reaction proceeds in neutral solvent under air or dioxygen (O2) with a photoredox catalyst excited by blue light-emitting diode light and an iodine co-catalyst that is either added as molecular iodine or generated in situ from alkyl iodides. Mechanistic investigations indicate that photosensitized O2 plays a vital role in the generation of carbon-centered radicals for both the addition of active methylene compounds to alkenes and the ring closure.
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Banco de datos:
MEDLINE
Idioma:
En
Revista:
Science
Año:
2023
Tipo del documento:
Article
País de afiliación:
Estados Unidos