75354-08-4Relevant articles and documents
Photocatalytic Giese-Type Reaction with Alkylsilicates Bearing C,O-Bidentate Ligands
Morofuji, Tatsuya,Matsui, Yu,Ohno, Misa,Ikarashi, Gun,Kano, Naokazu
supporting information, p. 6713 - 6718 (2021/02/26)
Herein, a photocatalytic Giese-type reaction with alkylsilicates bearing C,O-bidentate ligands as stable alkyl radical precursors has been reported. The alkylsilicates were prepared in one step from organometallic reagents. Not only primary, secondary, and tertiary alkyl radicals, but also elusive methyl radicals, could be generated by using the present reaction system. The generated radicals were trapped by electron-deficient olefins bearing various functional groups to give the desired alkyl adducts. The silicon byproduct can be recovered after the photoreaction. The radical generation process was investigated by theoretical calculations, which provided an insight into the facile generation of methyl radicals from methylsilicate bearing C,O-bidentate ligands.
Photochemical Hydroacylation of Michael Acceptors Utilizing an Aldehyde as Photoinitiator
Sideri, Ioanna K.,Voutyritsa, Errika,Kokotos, Christoforos G.
, p. 4194 - 4201 (2019/08/30)
The hydroacylation of Michael acceptors constitutes a useful tool for the formation of new C?C bonds. In this work, an environmentally friendly procedure was developed, utilizing 4cyanobenzaldehyde as the photoinitiator and household bulbs as the irradiation source. A great variety of substrates was well-tolerated, leading to good yields, and mechanistic experiments were performed to elucidate the catalyst's possible mechanistic pathway. Moreover, the inherent selectivity challenge regarding α,α-disubstituted aldehydes (decarbonylation problem) was studied and addressed.
Hydrogen Atom Transfer Reactions via Photoredox Catalyzed Chlorine Atom Generation
Rohe, Samantha,Morris, Avery O.,McCallum, Terry,Barriault, Louis
supporting information, p. 15664 - 15669 (2018/10/26)
The selective functionalization of chemically inert C?H bonds remains to be fully realized in achieving organic transformations that are redox-neutral, waste-limiting, and atom-economical. The catalytic generation of chlorine atoms from chloride ions is one of the most challenging redox processes, where the requirement of harsh and oxidizing reaction conditions renders it seldom utilized in synthetic applications. We report the mild, controlled, and catalytic generation of chlorine atoms as a new opportunity for access to a wide variety of hydrogen atom transfer (HAT) reactions owing to the high stability of HCl. The discovery of the photoredox mediated generation of chlorine atoms with Ir-based polypyridyl complex, [Ir(dF(CF3)ppy)2(dtbbpy)]Cl, under blue LED irradiation is reported.
Synthesis and stereochemical assignment of geraniol- and nerol-derived Cygerol enantiomers
Sukhanova, Anna A.,Puchkin, Ilya A.,Vasil'ev, Andrei A.,Zlotin, Sergei G.
, p. 1834 - 1841 (2017/11/20)
The enantiomers (up to 99% ee) of both geraniol- and nerol-derived 2-cyclohexyl-5,9-dimethyldeca-4,8-dienoic acid, the active ingredient of the wound healing medication Cygerol, were prepared via a low-temperature alkylation, basic hydrolysis, derivatization with (S)-4-benzyloxazolidin-2-one and chromatographic separation steps. The absolute configuration of stereocenters in the antipodes having an (E)- or (Z)-geometry of the internal double bond was determined based on characteristic 1H NMR signals of the corresponding (S)-4-benzyloxazolidin-2-one-derived imides and on conversion to the known diethyl (S)-2-cyclohexylsuccinate and (S)-2-cyclohexylbutane-1,4-diol with reported specific rotations.
Redox-economical radical generation from organoborates and carboxylic acids by organic photoredox catalysis
Chinzei, Tatsuya,Miyazawa, Kazuki,Yasu, Yusuke,Koike, Takashi,Akita, Munetaka
, p. 21297 - 21300 (2015/03/18)
A simple generation method of carbon radicals via 1e-oxidation of organotrifluoroborates and carboxylic acids by the action of an organophotoredox catalyst, 9-mesityl-10-methylacridinium perchlorate ([Acr+-Mes]ClO4), has been developed. This organophotocatalytic protocol is amenable to radical C-C bond formation with electron-deficient olefins.
On the cis-Effect of Radical Addition Reactions at Alkenes
Giese, Bernd,Lachhein, Stephen
, p. 1616 - 1620 (2007/10/02)
The trans-alkenes 2e - h react faster with cyclohexyl radicals than the cis-alkenes 3e - h (Table 1).Radical addition reactions at alkylidenemalonic esters 1 show that this cis-effect increases with the bulkyness of the substituents (Table 1).However, the difference in the reactivity between trans- and cis-alkenes exerts no effect on the regioselectivity (Table 3).It is concluded that the reason for the cis-effect is a twisting of the ?-system that influences the reactivity of both vinylic C-atoms to the same extent.
Selectivity of prim., sec. and tert. Alkyl Radicals in Addition Reactions
Giese, Bernd,Kretzschmar, Gerhard,Meixner, Juergen
, p. 2787 - 2795 (2007/10/02)
In reductions of alkylmercuric salts 4 and 5 with NaBH4 alkyl radicals 1 are formed as intermediates.The selectivity of prim., sec. and tert. radicals in addition reactions with alkenes 6-12 can be measured by this "mercury-method", because adduct radicals 13-19 form products 20-26 quantitatively.Dimerization, disproportionation, polymerization, trapping of oxygen and β-bond cleavage don't compete with the hydrogen transfer to 13-19.The measurements show, that alkyl radicals 1 are nucleophiles and that their selectivity increases in going from prim. to sec. and tert. radicals (Table 1).As long as steric effects are not important, reactivities and selectivities can be described by frontier molecular orbital theory.As a consequence of this theory selectivity increases with increasing reactivity.
