72936-07-3Relevant articles and documents
Organo-photoredox-catalyzed atom-transfer radical substitution of alkenes with α-carbonyl alkyl halides
Nishikata, Takashi,Hirata, Goki,Shimada, Taisei
supporting information, p. 8952 - 8956 (2020/12/02)
A light-driven atom-transfer radical substitution (ATRS) and carboesterification reaction of alkenes with alkyl halides has been developed using PTH as the organo-photoredox catalyst. Two types of products were obtained, depending on the additive and solvent used during the reaction. Primary, secondary, and tertiary alkyl halides reacted to give the ATRS products. This protocol has several advantages: it requires mild reaction conditions and a low catalyst loading and exhibits a broad substrate scope and good functional group tolerance. Mechanistic studies indicate that alkyl radicals might be generated as the key intermediates via photocatalysis, providing a new direction for ATRS reactions.
Deaminative (Carbonylative) Alkyl-Heck-type Reactions Enabled by Photocatalytic C?N Bond Activation
Jiang, Xuan,Zhang, Mao-Mao,Xiong, Wei,Lu, Liang-Qiu,Xiao, Wen-Jing
supporting information, p. 2402 - 2406 (2019/01/29)
The palladium-catalyzed Heck reaction is a well-known, Nobel Prize winning transformation for producing alkenes. Unlike the alkenyl and aryl variants of the Heck reaction, the alkyl-Heck reaction is still underdeveloped owing to the competitive side reactions of alkyl–palladium species. Herein, we describe the development of a deaminative alkyl-Heck-type reaction that proceeds through C?N bond activation by visible-light photoredox catalysis. A variety of aliphatic primary amines were found to be efficient starting materials for this new process, affording the corresponding alkene products in good yields under mild reaction conditions. Moreover, this strategy was successfully applied to deaminative carbonylative alkyl-Heck-type reactions.
Vitamin B12 Catalysis: Probing the Structure/Efficacy Relationship
Karczewski, Maksymilian,Ociepa, Micha?,Pluta, Katarzyna,ó Proinsias, Keith,Gryko, Dorota
supporting information, p. 7024 - 7030 (2017/05/29)
Vitamin B12 is a cofactor for many enzymes, but it also functions as a catalyst in C?C bond-forming reactions. Herein, the impact of corrin structural modifications on their catalytic efficacy was examined. Derivatives with various substituents at c-, d-, and meso-positions were synthesised by using traditional and new microwave methodologies, and then tested in the model reaction of 1,1-diphenylethylene with ethyl diazoacetate. To complement the experimental data, cyclic voltammetry and DFT calculations were performed. Mainly alterations at the c- or d-positions influence both the reaction yield and selectivity.
Cobalt(i)-catalysed CH-alkylation of terminal olefins, and beyond
Giedyk, Maciej,Goliszewska, Katarzyna,ó Proinsias, Keith,Gryko, Dorota
supporting information, p. 1389 - 1392 (2016/01/25)
Cobalester, a natural nontoxic vitamin B12 derivative, was found to catalyse unusual olefinic sp2 C-H alkylation with diazo reagents as a carbene source instead of the expected cyclopropanation.
Asymmetric Catalysis with Organic Azides and Diazo Compounds Initiated by Photoinduced Electron Transfer
Huang, Xiaoqiang,Webster, Richard D.,Harms, Klaus,Meggers, Eric
supporting information, p. 12636 - 12642 (2016/10/07)
Electron-acceptor-substituted aryl azides and α-diazo carboxylic esters are used as substrates for visible-light-activated asymmetric α-amination and α-alkylation, respectively, of 2-acyl imidazoles catalyzed by a chiral-at-metal rhodium-based Lewis acid in combination with a photoredox sensitizer. This novel proton- and redox-neutral method provides yields of up to 99% and excellent enantioselectivities of up to >99% ee with broad functional group compatibility. Mechanistic investigations suggest that an intermediate rhodium enolate complex acts as a reductive quencher to initiate a radical process with the aryl azides and α-diazo carboxylic esters serving as precursors for nitrogen and carbon-centered radicals, respectively. This is the first report on using aryl azides and α-diazo carboxylic esters as substrates for asymmetric catalysis under photoredox conditions. These reagents have the advantage that molecular nitrogen is the leaving group and sole byproduct in this reaction.
Visible-light photocatalytic radical alkenylation of a-carbonyl alkyl bromides and benzyl bromides
Liu, Qiang,Yi, Hong,Liu, Jie,Yang, Yuhong,Zhang, Xu,Zeng, Ziqi,Lei, Aiwen
supporting information, p. 5120 - 5126 (2013/06/27)
Through the use of [Ru- (bpy)3Cl2] (bpy=2,2'-bipyridine) and [Ir(ppy)3] (ppy=phenylpyridine) as photocatalysts, we have achieved the first example of visible-light photocatalytic radical alkenylation of various acarbonyl alkyl bromides and benzyl bromides to furnish a-vinyl carbonyls and allylbenzene derivatives, prominent structural elements of many bioactive molecules. Specifically, this transformation is regiospecific and can tolerate primary, secondary, and even tertiary alkyl halides that bear b-hydrides, which can be challenging with traditional palladium-catalyzed approaches. The key initiation step of this transformation is visible-light-induced single-electron reduction of CBr bonds to generate alkyl radical species promoted by photocatalysts. The following carboncarbon bond-forming step involves a radical addition step rather than a metal-mediated process, thereby avoiding the undesired b-hydride elimination side reaction. Moreover, we propose that the Ru and Ir photocatalysts play a dual role in the catalytic system: they absorb energy from the visible light to facilitate the reaction process and act as a medium of electron transfer to activate the alkyl halides more effectively. Overall, this photoredox catalysis method opens new synthetic opportunities for the efficient alkenylation of alkyl halides that contain b-hydrides under mild conditions.
Stereoseleetive Syntheses of β,γ-Unsaturated Esters and γ-Lactones: 1-(Benzotriazol-1-yl)-3-(diphenylphosphoryl)-1-ethoxy-1-propene, a Protected =CCH2CO2Et Synthon Equivalent
Katritzky, Alan R.,Feng, Daming,Lang, Hengyuan
, p. 4131 - 4136 (2007/10/03)
l-(Benzotriazol-l-yl)-3-(diphenylphosphoryl)-l-ethoxy-l-propene (3), prepared from N-(α-ethoxyallyl)benzotriazole (1), underwent selective Horner reactions with aldehydes to give substituted dienes. Subsequent hydrolysis of these intermediates readily produced β,γ-unsaturated esters 2a-c in good yields. Similar reactions with ketones followed by hydrolysis of 10 produced, depending on the conditions, either the corresponding γ,γ-disubstituted β,γ-unsaturated esters 11a-d or γ-lactones 9a-c and 13. A double lithiation process provided β,γ,γ-trisubstituted β,γ-unsaturated esters 15, 18, and β,γ,γ-trisubstituted γ-lactone 14.
Reaction of Olefins with Malonic Acid Derivatives in the Presence of Manganese(III) Acetate
Fujimoto, Noriyuki,Nishino, Hiroshi,Kurosawa, Kazu
, p. 3161 - 3168 (2007/10/02)
The reaction of methylmalonic acid with mono- and disubstituted olefins in the presence of manganese(III) acetate yielded 2-carboxy-2-methyl-4-butanolides in moderate to good yields.The reactions of bromomalonic acid and chloromalonic acid with a variety
