title: Photochemical activity of a key donor-acceptor complex can drive stereoselective catalytic α-alkylation of aldehydes.
abstract: Asymmetric catalytic variants of sunlight-driven photochemical processes hold extraordinary potential for the sustainable preparation of chiral molecules. However, the involvement of short-lived electronically excited states inherent to any photochemical reaction makes it challenging for a chiral catalyst to dictate the stereochemistry of the products. Here, we report that readily available chiral organic catalysts, with well-known utility in thermal asymmetric processes, can also confer a high level of stereocontrol in synthetically relevant intermolecular carbon-carbon bond-forming reactions driven by visible light. A unique mechanism of catalysis is proposed, wherein the catalyst is involved actively in both the photochemical activation of the substrates (by inducing the transient formation of chiral electron donor-acceptor complexes) and the stereoselectivity-defining event. We use this approach to enable transformations that are extremely difficult under thermal conditions, such as the asymmetric α-alkylation of aldehydes with alkyl halides, the formation of all-carbon quaternary stereocentres and the control of remote stereochemistry.
authors: 1] Institute of Chemical Research of Catalonia, Avenguda Països Catalans 16-43007 Tarragona, Spain [2].
authors: Elena
authors: E
authors: Arceo
authors: Igor D
authors: ID
authors: Jurberg
authors: Ana
authors: A
authors: Alvarez-Fernández
authors: Paolo
authors: P
authors: Melchiorre
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D000478:Alkylation; D002384:Catalysis; D004583:Electrons; D011725:Pyridines / Q000737:chemistry; D013237:Stereoisomerism; D014466:Ultraviolet Rays
chemical_list: D000447:Aldehydes; D011725:Pyridines; C013093:2,6-lutidine
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