2439-44-3Relevant articles and documents
Mild Iridium-Catalysed Isomerization of Epoxides. Computational Insights and Application to the Synthesis of β-Alkyl Amines
Cabré, Albert,Cabezas-Giménez, Juanjo,Sciortino, Giuseppe,Ujaque, Gregori,Verdaguer, Xavier,Lledós, Agustí,Riera, Antoni
, p. 3624 - 3631 (2019/07/10)
The isomerization of epoxides to aldehydes using the readily available Crabtree's reagent is described. The aldehydes were transformed into synthetically useful amines by a one-pot reductive amination using pyrrolidine as imine-formation catalyst. The reactions worked with low catalyst loadings in very mild conditions. The procedure is operationally simple and tolerates a wide range of functional groups. A DFT study of its mechanism is presented showing that the isomerization takes place via an iridium hydride mechanism with a low energy barrier, in agreement with the mild reaction conditions. (Figure presented.).
Ligand-Controlled Direct Hydroformylation of Trisubstituted Olefins
Shin, Taeil,Kim, Hyungsoo,Kim, Sungmin,Lee, Ansoo,Seo, Min-Seob,Choi, Jonghoon,Kim, Hyungjun,Kim, Hyunwoo
supporting information, p. 5789 - 5792 (2019/06/24)
The direct hydroformylation of trisubstituted olefins has been achieved with a combination of a Rh(I) catalyst and a π-acceptor phosphorus (briphos) ligand. A sterically bulky briphos ligand with a large cone angle that forms a 1:1 complex with Rh(I) is found to be reactive for the hydroformylation of trisubstituted olefins. The aldehyde products were obtained with high diastereoselectivity (>99:1) and regioselectivity (49%-81%).
Copper-catalyzed vinylogous aerobic oxidation of unsaturated compounds with air
Zhang, Hai-Jun,Schuppe, Alexander W.,Pan, Shi-Tao,Chen, Jin-Xiang,Wang, Bo-Ran,Newhouse, Timothy R.,Yin, Liang
, p. 5300 - 5310 (2018/04/24)
A mild and operationally simple copper-catalyzed vinylogous aerobic oxidation of β,γ- and α,β-unsaturated esters is described. This method features good yields, broad substrate scope, excellent chemo- and regioselectivity, and good functional group tolerance. This method is additionally capable of oxidizing β,γ- and α,β-unsaturated aldehydes, ketones, amides, nitriles, and sulfones. Furthermore, the present catalytic system is suitable for bisvinylogous and trisvinylogous oxidation. Tetramethylguanidine (TMG) was found to be crucial in its role as a base, but we also speculate that it serves as a ligand to copper(II) triflate to produce the active copper(II) catalyst. Mechanistic experiments conducted suggest a plausible reaction pathway via an allylcopper(II) species. Finally, the breadth of scope and power of this methodology are demonstrated through its application to complex natural product substrates.
Rhodium-catalyzed asymmetric hydrogenation of β-branched enamides for the synthesis of β-stereogenic amines
Zhang, Jian,Liu, Chong,Wang, Xingguang,Chen, Jianzhong,Zhang, Zhenfeng,Zhang, Wanbin
, p. 6024 - 6027 (2018/06/18)
Using a rhodium complex of a bisphosphine ligand (R)-SDP, β-branched simple enamides with a (Z)-configuration were hydrogenated to β-stereogenic amines in quantitative yields and with excellent enantioselectivities (88-96% ee).
Enantioselective Rhodium-Catalyzed Allylic Alkylation of Prochiral α,α-Disubstituted Aldehyde Enolates for the Construction of Acyclic Quaternary Stereogenic Centers
Wright, Timothy B.,Evans, P. Andrew
, p. 15303 - 15306 (2016/12/09)
A highly enantioselective rhodium-catalyzed allylic alkylation of prochiral α,α-disubstituted aldehyde enolates with allyl benzoate is described. This protocol provides a novel approach for the synthesis of acyclic quaternary carbon stereogenic centers and it represents the first example of the direct enantioselective alkylation of an aldehyde enolate per se. The versatility of the α-quaternary aldehyde products is demonstrated through their conversion to a variety of useful motifs applicable to target-directed synthesis. Finally, mechanistic studies indicate that high levels of asymmetric induction are achieved from a mixture of prochiral (E)- and (Z)-enolates, which provides an exciting development for this type of transformation.
Anti-Markovnikov Oxidation of β-Alkyl Styrenes with H2O as the Terminal Oxidant
Zhang, Guoting,Hu, Xia,Chiang, Chien-Wei,Yi, Hong,Pei, Pengkun,Singh, Atul K.,Lei, Aiwen
supporting information, p. 12037 - 12040 (2016/09/28)
Oxygenation of alkenes is one of the most straightforward routes for the construction of carbonyl compounds. Wacker oxidation provides a broadly useful strategy to convert the mineral oil into higher value-added carbonyl chemicals. However, the conventional Wacker chemistry remains problematic, such as the poor activity for internal alkenes, the lack of anti-Markovnikov regioselectivity, and the high cost and chemical waste resulted from noble metal catalysts and stoichiometric oxidant. Here, we describe an unprecedented dehydrogenative oxygenation of β-alkyl styrenes and their derivatives with water under external-oxidant-free conditions by utilizing the synergistic effect of photocatalysis and proton-reduction catalysis that can address these challenges. This dual catalytic system possesses the single anti-Markovnikov selectivity due to the property of the visible-light-induced alkene radical cation intermediate.
Vicinal Functionalization of N-Alkoxyenamines: Tandem Umpolung Phenylation-Nucleophilic Addition Reaction Sequence
Sato, Shohei,Takeda, Norihiko,Miyoshi, Tetsuya,Ueda, Masafumi,Miyata, Okiko
supporting information, p. 3899 - 3904 (2015/06/30)
The vicinal functionalization of N-alkoxyenamines, derived in situ from aldehydes and isoxazolidines, has been achieved with the formation of two new carbon-carbon bonds by utilizing an organo-aluminum reagent and subsequent allylmagnesium bromide or tributyltin cyanide as external carbon-centered nucleophiles. By changing the second carbon nucleophile, various amine derivatives were obtained in good yields. An efficient and four-component reaction was developed. The double nucleophilic reaction of N-alkoxyenamines, derived in situ from aldehyde and isoxazolidine, afforded functionalized amines.
An air-stable cationic iridium hydride as a highly active and general catalyst for the isomerization of terminal epoxides
Humbert, Nicolas,Vyas, Devendra J.,Besnard, Céline,Mazet, Clément
supporting information, p. 10592 - 10595 (2014/10/15)
We describe the use of an air-stable iridium hydride catalyst for the isomerization of terminal epoxides into aldehydes with perfect regioselectivity. The system operates at low loadings of catalyst (0.5 mol%), is highly practical, scalable, and tolerates functional groups that would not be compatible with Lewis acids typically used in stoichiometric amounts. Evidence for a rare hydride mechanism are provided. This journal is the Partner Organisations 2014.
α-Arylation, α-arylative esterification, or acylation: A stoichiometry-dependent trichotomy in the Pd-catalyzed cross-coupling between aldehydes and aryl bromides
Nareddy, Pradeep,Mazet, Clement
supporting information, p. 2579 - 2583 (2013/11/19)
Three′s company: The selective α-arylation and α-arylative esterification of linear and branched aldehydes is reported for a variety of bromoarenes. The acylation of aryl bromides can be achieved with linear aldehydes (see scheme). All these transformations were performed with a single [(N-heterocyclic carbene)Pd] catalyst through adjustment of the stoichiometry of the reagents and the appropriate base. Copyright
Isomerization of terminal epoxides by a [Pd-H] catalyst: A combined experimental and theoretical mechanistic study
Vyas, Devendra J.,Larionov, Evgeny,Besnard, Celine,Guenee, Laure,Mazet, Clement
supporting information, p. 6177 - 6183 (2013/06/04)
An unusual palladium hydride complex has been shown to be a competent catalyst in the isomerization of a variety of terminal and internal epoxides. The reaction displayed broad scope and synthetic utility. Experimental and theoretical evidence are provided for an unprecedented hydride mechanism characterized by two distinct enantio-determining steps. These results hold promise for the development of an enantioselective variant of the reaction.
