22913-11-7Relevant academic research and scientific papers
Metal-free radical aromatic carbonylations mediated by weak bases
Koziakov, Denis,Jacobi Von Wangelin, Axel
supporting information, p. 6715 - 6719 (2017/08/22)
We report a new method of metal-free alkoxycarbonylation. This reaction involves the generation of aryl radicals from arenediazonium salts by a very weak base (HCO2Na) under mild conditions. Subsequent radical trapping with carbon monoxide and alcohols gives alkyl benzoates. The conditions (metal-free, 1 equiv. base, MeCN, r.t., 3 h) tolerate various functional groups (I, Br, Cl, CF3, SF5, NO2, ester). Mechanistic studies indicate the operation of a radical aromatic substitution mechanism.
Transfer Hydrogenation of Nitriles, Olefins, and N-Heterocycles Catalyzed by an N-Heterocyclic Carbene-Supported Half-Sandwich Complex of Ruthenium
Mai, Van Hung,Nikonov, Georgii I.
supporting information, p. 943 - 949 (2016/05/09)
In the presence of KOBut, N-heterocyclic carbene-supported half-sandwich complex [Cp(IPr)Ru(pyr)2][PF6] (3) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) catalyzes transfer hydrogenation (TH) of nitriles, activated N-heterocycles, olefins, and conjugated olefins in isopropanol at the catalyst loading of 0.5%. The TH of nitriles leads to imines, produced as a result of coupling of the initially formed amines with acetone (produced from isopropanol), and showed good chemoselectivity. Reduction of N-heterocycles occurs for activated polycyclic substrates (e.g., quinoline) and takes place exclusively in the heterocycle. The TH also works well for linear and cyclic olefins but fails for trisubstituted substrates. However, the C = C bond of α,β-unsaturated esters, amides, and acids is easily reduced even for trisubstituted species, such as isovaleriates. Mechanistic studies suggest that the active species in these catalytic reactions is the trihydride Cp(IPr)RuH3 (5), which can catalyze these reactions in the absence of any base. Kinetic studies are consistent with a classical inner sphere hydride-based mechanism of TH.
Dimethylbut-2-ynedioate mediated esterification of acids via sp3 C-N bond cleavage of benzylic tertiary amines
Shen, Hao,Lu, Xing,Jiang, Ke-Zhi,Yang, Ke-Fang,Lu, Yixin,Zheng, Zhan-Jiang,Lai, Guo-Qiao,Xu, Li-Wen
, p. 8916 - 8923 (2012/10/29)
A straightforward synthetic transformation of tertiary amines to the esterification of equimolar amounts of acids was demonstrated in this manuscript. The present protocol can be regarded as a straightforward synthetic transformation of tertiary amines to the esterification of equimolar amounts of acid. Moreover, the reaction is fundamentally new chemistry for the sp 3 C-N bond cleavage coupled with esterification. The esterification reaction conditions are very mild and functional group-tolerated, such as hydrosilanes, alcohols, phenol, and amino acids. A mechanism is proposed in which the tertiary amine reacts with dimethyl but-2-ynedioate to form zwitterionic salt, and then the zwitterionic intermediate subsequently accept hydrogen to assist the nucleophilic attack of oxygen atom of carboxyl group at the benzyl group of tertiary amine, while a separate reaction pathway leads to esterification.
Acylative cleavage of ethers with ZnCl2
Yu, Yun-Feng,Gao, Jian-Rong,Jiang, Shao-Liang,Han, Liang,Jia, Jian-Hong,Li, Yu-Jin
experimental part, p. 5199 - 5201 (2012/09/21)
Acylative cleavage of common ether solvents with ZnCl2 was reported. Different substituted acyl chlorides were reacted with the common ether solvents in the presence of ZnCl2 to obtain the corresponding substituted benzoate.
Rhenium complex-catalyzed acylative cleavage of ethers with acyl chlorides
Umeda, Rui,Nishimura, Takashi,Kaiba, Kenta,Tanaka, Toshimasa,Takahashi, Yuuki,Nishiyama, Yutaka
experimental part, p. 7217 - 7221 (2011/10/08)
It was found that rhenium complex was an efficient catalyst for the acylative cleavage of C-O bond of ethers with acyl chlorides. When acyclic ethers were allowed to react with acyl chlorides in the presence of a catalytic amount of ReBr(CO)5, acylative cleavage of C-O bond of acyclic ethers smoothly proceeded to give the corresponding esters in moderate to good yields. Similarly, cyclic ethers were acylative cleaved by acyl chlorides to give the corresponding chloro substituted esters in good yields by the use of Re 2O7 catalyst.
Rhenium complex as a useful catalyst for acylative cleavage of ethers
Umeda, Rui,Kaiba, Kenta,Tanaka, Toshimasa,Takahashi, Yuuki,Nishimura, Takashi,Nishiyama, Yutaka
experimental part, p. 3089 - 3091 (2011/02/25)
It was found that a rhenium complex such as ReBr(CO)5 acts as an efficient catalyst for the acylative cleavage of the carbon-oxygen bond of ethers with acyl chloride, giving the corresponding esters in moderate to good yields.
Palladium-catalyzed aerobic oxidative carbonylation of arylboronate esters under mild conditions
Liu, Qiang,Li, Gang,He, Jun,Liu, Jing,Li, Peng,Lei, Aiwen
supporting information; experimental part, p. 3371 - 3374 (2010/07/06)
(Figure Presented) "CO"n Air: The title reaction was carried out using [PdCl2(PPh3)2 ] as the catalyst precursor under very mild conditions (balloon pressure of CO and air, at 40- 50°C), and produced a wide range of aryl carboxyl esters 2 in good to excellent yields. Remarkable selectivity between oxidative carbonylation and homocoupling of arylboronate esters l was also achieved.
The first general and selective palladium(II)-catalyzed alkoxycarbonylation of arylboronates: Interplay among benzoquinone-ligated palladium(0) complex, organoboron, and alcohol solvent
Yamamoto, Yoshihiko
supporting information; experimental part, p. 478 - 492 (2010/07/03)
Methoxycarbonylation of aryl- and alken-ylboron compounds was performed using the palladium (II) acetate/triphenylphosphine [PdACHTUNGTRENNUNG(OAc) 2/PPh3] catalyst with p-benzoquinone as a stoichiometric oxidant in methanol at ambient temperature to obtain the corresponding methyl esters in good yields. A wide variety of functional groups including various carbonyl functionalities, nitrile, nitro, sulfone, and unprotected pyrrole rings were tolerated in the methoxycarbonlation, while the use of higher alcohols except for tert-butanol afforded various pchlorobenzoates in moderate to high yields. The catalytic alkoxycarbonylation proceeded without any acid or base additive, and an oxidative transmetalation step is proposed to explain the exceptional efficacy of this protocol. DFT and MP2 calculations support the proposed mechanism.
Scope and mechanistic insights into the use of tetradecyl(trihexyl) phosphonium bistriflimide: A remarkably selective ionic liquid solvent for substitution reactions
McNulty, James,Nair, Jerald J.,Cheekoori, Sreedhar,Larichev, Vladimir,Capretta, Alfredo,Robertson
, p. 9314 - 9322 (2007/10/03)
A survey of substitution reactions conducted in a phosphonium bistriflimide ionic liquid is presented. The results demonstrate high selectivity favoring substitution over typically competitive elimination and solvolytic processes even when challenging secondary and tertiary electrophiles are employed. The first reports of Kornblum substitution reactions in an ionic liquid are described that proceed with very high chemoselectivity in favor of nitro over nitroso products and elimi nation side products. The structure-reactivity study indicates that these reactions proceed through a narrow spectrum of pathways ranging from straight SN2 to a preassociation pathway along a saddle point that approaches the SN1 limit. The barrier to the formation of dissociated carbocations is attributed to the structural features of this ionic liquid that favor intervention of the associated nucleophile over dissociation, also preventing cross over to E1 processes. The lack of any basic entity in the phosphonium bistriflimide ionic liquid appears to prevent any potential base-mediated elimination reactions, which makes this a highly selective medium for use in general substitution reactions.
A fast and simple method for the acylation of alcohols with acid chlorides promoted by metallic samarium
Jia, Xue-Shun,Wang, Hai-Long,Huang, Qing,Kong, Ling-Long,Zhang, Wei-He
, p. 135 - 138 (2007/10/03)
Acylation of primary, secondary, allyl and benzyl alcohols with acid chlorides promoted by samarium metal under neutral condition gave carboxylic acid esters in good to excellent yields. Acylation of a tertiary alcohol did not occur under the same reaction conditions.
