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Electrophilic Radicals (electrophilic + radical)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 8 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Gas-phase radical,radical recombination reactions of nitroxides with substituted phenyl radicals

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 4 2004
J. L. Heidbrink
Fourier-transform ion cyclotron resonance mass spectrometry has been used to examine gas-phase reactions of four different nitroxide free radicals with eight positively charged pyridyl and phenyl radicals (some containing a Cl, F, or CF3 substituent). All the radicals reacted rapidly (near collision rate) with nitroxides by radical,radical recombination. However, some of the radicals were also able to abstract a hydrogen atom from the nitroxide. The results establish that the efficiency (kreaction/kcollision) of hydrogen atom abstraction varies with the electrophilicity of the radical, and hence is attributable to polar effects (a lowering of the transition-state energy by an increase in its polar character). The efficiency of the recombination reaction is not sensitive to substituents, presumably due to a very low reaction barrier. Even so, after radical,radical recombination has occurred, the nitroxide adduct was found to fragment in different ways depending on the structure of the radical. For example, a cationic fragment was eliminated from the adducts of the more electrophilic radicals via oxygen anion abstraction by the radical (i.e., the nitroxide adduct cleaves heterolytically), whereas adducts of the less electrophilic radicals predominantly fragmented via homolytic cleavage (oxygen atom abstraction). Therefore, differences in the product branching ratios were found to be attributable to polar factors. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 216,229 2004 [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 8 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]

Cover Picture: (Adv. Synth.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1 2010
Catal.
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)32+ readily accepts a photon from a visible light source to populate the *Ru(bpy)32+ 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 ,-rich olefin followed by a series of concerted steps which return the organocatalyst and photocatalyst to their respective cycles and render the optically enriched ,-alkyl aldehyde. [source]