Catalytic asymmetric C-C cross-couplings enabled by photoexcitation.
Nat Chem
; 13(6): 575-580, 2021 06.
Article
in En
| MEDLINE
| ID: mdl-34031564
ABSTRACT
Enantioselective catalytic processes are promoted by chiral catalysts that can execute a specific mode of catalytic reactivity, channeling the chemical reaction through a certain mechanistic pathway. Here, we show how by simply using visible light we can divert the established ionic reactivity of a chiral allyl-iridium(III) complex to switch on completely new catalytic functions, enabling mechanistically unrelated radical-based enantioselective pathways. Photoexcitation provides the chiral organometallic intermediate with the ability to activate substrates via an electron-transfer manifold. This redox event unlocks an otherwise inaccessible cross-coupling mechanism, since the resulting iridium(II) centre can intercept the generated radicals and undergo a reductive elimination to forge a stereogenic centre with high stereoselectivity. This photochemical strategy enables difficult-to-realize enantioselective alkyl-alkyl cross-coupling reactions between allylic alcohols and readily available radical precursors, which are not achievable under thermal activation.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Nat Chem
Journal subject:
QUIMICA
Year:
2021
Type:
Article
Affiliation country:
Spain