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Cover Picture: (Adv. Synth. Catal. 18/2010)
Publication year - 2010
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Reports
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201090034
Subject(s) - chemistry , photoredox catalysis , electrophile , enamine , catalytic cycle , alkylation , aldehyde , organocatalysis , photochemistry , catalysis , enantioselective synthesis , organic chemistry , photocatalysis
The cover picture, provided by David W. C. MacMillan, shows a dual‐catalytic aldehyde alkylation via photoredox organocatalysis in which electrophilic radicals (derived from the photoredox cycle; above) combine with facially biased enamine intermediates (derived from the organocatalytic cycle; below). The photoredox catalyst, Ru(bpy) 3 2+ readily accepts a photon from a visible light source to populate the *Ru(bpy) 3 2+ metal‐to‐ligand charge transfer (MLCT) excited state, eventually enabling single‐electron transfer (SET) with an alkyl halide to furnish the electron‐deficient alkyl radical. Simultaneously, the organocatalytic cycle is initiated upon condensation of the imidazolidinone catalyst (inset) exclusively with a non‐substituted aldehyde to form a stereochemically‐defined enamine. The two activation pathways merge in the key alkylation step via rapid addition of the electrophilic radical to the π‐rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched α‐alkyl aldehyde.