1566-65-0Relevant articles and documents
Iridium-Catalyzed Enantioselective Allylic Substitution of Enol Silanes from Vinylogous Esters and Amides
Chen, Ming,Hartwig, John F.
, p. 13972 - 13979 (2015)
The enol silanes of vinylogous esters and amides are classic dienes for Diels-Alder reactions. Here, we report their reactivity as nucleophiles in Ir-catalyzed, enantioselective allylic substitution reactions. A variety of allylic carbonates react with these nucleophiles to give allylated products in good yields with high enantioselectivities and excellent branched-to-linear ratios. These reactions occur with KF or alkoxide as the additive, but mechanistic studies suggest that these additives do not activate the enol silanes. Instead, they serve as bases to promote the cyclometalation to generate the active Ir catalyst. The carbonate anion, which was generated from the oxidative addition of the allylic carbonate, likely activates the enol silanes to trigger their activity as nucleophiles for reactions with the allyliridium electrophile. The synthetic utility of this method was illustrated by the synthesis of the anti-muscarinic drug, fesoterodine.
Stereoselective Synthesis of Vinylboronates by Rh-Catalyzed Borylation of Stereoisomeric Mixtures
Li, Shenhuan,Li, Jie,Xia, Tianlai,Zhao, Wanxiang
supporting information, p. 462 - 468 (2019/03/28)
The stereoselective preparation of vinylboronates via rhodium-catalyzed borylation of E/Z mixtures of vinyl actetates is described, and this method was also extended to synthesis of vinyldiboronates. These transformations feature high functional group compatibility and mild reaction conditions. Control experiments support a mechanism that involved a Rh-catalyzed borylation-isomerization sequence. The isomerization of (Z)-vinylboronates to (E)-isomers was also demonstrated.
A cost-effective shortcut to prepare organoselenium catalysts via decarboxylative coupling of phenylacetic acid with elemental selenium
Cao, Hongen,Liu, Mingxuan,Qian, Rongrong,Zhang, Xu,Yu, Lei
, (2018/11/25)
An interesting decarboxylative coupling reaction of phenylacetic acid with elemental selenium was discovered and employed for the preparation efficient organoselenium catalysts for Baeyer–Villiger reaction and oxidative deoximation reaction. Compared with the traditionally used Grignard reagent method, the decarboxylative coupling reaction with selenium powders provides a shortcut for the preparation of organoselenium catalysts free of carcinogenic organohalide starting materials, toxic and odorous selenol intermediates and magnesium salt solid wastes. This may be helpful for reducing the cost of selenium catalysts to facilitate the application of organoselenium-catalyzed green reactions in large-scale production.
Carboxylic acid addition to terminal alkynes utilizing ammonium tagged Hoveyda-Grubbs catalyst supported on magnetically separable core/shell silica: A highly reusable and air compatible catalytic system
?ztürk, Bengi ?zgün,Gürcü, Didar,?ehito?lu, Solmaz Karabulut
, p. 11 - 16 (2019/01/24)
In this study, the performance of ammonium tagged Hoveyda-Grubbs catalyst supported on magnetically separable core/shell silica gel was tested on carboxylic acid addition reactions to terminal alkynes using a variety of carboxylic acid derivatives under air atmosphere. The catalytic system was found to be compatible with air atmosphere and can tolerate even non-degassed solvents. The reaction parameters such as temperature, substrate/catalyst ratio and the effect of carboxylic acid on the selectivity and yield of the reaction were investigated in details. The reaction of arylacetylenes with acetic acid yielded the corresponding E-isomer with conversion values up to 99% with a catalytic loading of 1% Ru. The reusability of the catalyst was tested using acetic acid/benzoic acid and phenylacetylene in toluene at 85 °C under air atmosphere. The catalyst was found to be highly reusable and maintained its activity up to 11th run, reaching a conversion value of 83% with minimum ruthenium leaching.
Cationic ruthenium complex of the formula [RuCl(2,6-diacetylpyridine)(PPh3)2]BArF and its catalytic activity in the formation of enol esters
Stark, Matthew J.,Tang, Douglas T.,Rath, Nigam P.,Bauer, Eike B.
supporting information, p. 873 - 877 (2018/02/09)
A new ruthenium 2,6-diacetylpyridine complex was synthesized and applied in the atom-economic synthesis of enol esters through Markovnikov-directed addition of carboxylic acids to terminal alkynes. The ruthenium complex [RuCl(dap)(PPh3)2]+BArF? was synthesized from [RuCl2(PPh3)2] and the corresponding ligand 2,6-diacetylpyridine (dap). The complex was characterized structurally. The new ruthenium complex was utilized under ambient conditions as a catalyst in the Markovnikov addition of carboxylic acids to terminal alkynes to afford the corresponding enol esters in 93% to 52% isolated yields (85 °C, 16 h reaction time, 1 mol% catalyst loading).
Pd0.09Ce0.91O2-Δ: A sustainable ionic solid-solution precatalyst for heterogeneous, ligand free Heck coupling reactions
Mpungose, Philani P.,Sehloko, Neo I.,Dasireddy, Venkata D.B.C.,Mahadevaiah, Narayanappa,Maguire, Glenn E.,Friedrich, Holger B.
, p. 60 - 68 (2017/11/15)
A quick and easy method for the preparation of Pd2+ metal ion substituted in ceria, Pd0.09Ce0.91O2-δ solid solution oxide, is described. The Pd0.09Ce0.91O2-δ solid solution oxide was fully characterized by XRD, ICP-OES, BET, XPS, SEM, EDX, TEM, TGA and Raman spectroscopy. All characterization techniques strongly suggested that Pd2+ was successfully incorporated into the lattice structure of ceria. The effect of the reaction conditions on the catalytic properties of the Pd0.09Ce0.91O2-δ solid solution catalyst initially was studied in detail with the model Heck reaction of iodobenzene and methylacrylate to obtain optimum reaction conditions. The Pd0.09Ce0.91O2-δ solid solution catalyst then afforded substituted alkenes in good to excellent yields under these optimum reaction conditions. Steric and electronic effects were also studied, and were found to influence the catalytic activity. Characterization of the used catalyst suggests that Pd2+ in Pd0.09Ce0.91O2-δ is reduced in situ to Pd0 when employed in the Heck cross-coupling reactions. The catalyst was easily recovered by centrifuge and reused three times without significant loss of catalytic efficiency.
Formyloxyacetoxyphenylmethane as an N-Formylating Reagent for Amines, Amino Acids, and Peptides
Chapman, Robert S. L.,Lawrence, Ruth,Williams, Jonathan M. J.,Bull, Steven D.
supporting information, p. 4908 - 4911 (2017/09/23)
Formyloxyacetoxyphenylmethane is a stable, water-tolerant, N-formylating reagent for primary and secondary amines that can be used under solvent-free conditions at room temperature to prepare a range of N-formamides, N-formylanilines, N-formyl-α-amino acids, N-formylpeptides, and an isocyanide.
Iron-Catalyzed Cross-Coupling of Alkenyl Acetates
G?rtner, Dominik,Stein, André Luiz,Grupe, Sabine,Arp, Johannes,Von Wangelin, Axel Jacobi
supporting information, p. 10545 - 10549 (2015/09/02)
Stable C-O linkages are generally unreactive in cross-coupling reactions which mostly employ more electrophilic halides or activated esters (triflates, tosylates). Acetates are cheap and easily accessible electrophiles but have not been used in cross-couplings because the strong C-O bond and high propensity to engage in unwanted acetylation and deprotonation. Reported herein is a selective iron-catalyzed cross-coupling of diverse alkenyl acetates, and it operates under mild reaction conditions (0 C, 2 h) with a ligand-free catalyst (1-2 mol%). Iron clad: Acetates are underutilized electrophiles in metal-catalyzed cross-coupling reactions because of the strong alkenyl C-O bond and their propensity to engage in unwanted reactions. Combination of a ligand-free low-valent Fe catalyst with nucleophilic organomagnesium reagents, low temperature, and short reaction times results in highly selective cross-couplings with alkenyl acetates.
Palladium-Catalyzed Arylation of Olefins by Triarylphosphines via C-P Bond Cleavage
Lu, Dapeng,Xu, Yu,Liu, Wenjing,Guo, Lijuan,Sun, Xingxia
, p. 116 - 122 (2015/10/19)
C-H Arylation of olefins by triarylphosphines via C-P bond cleavage has been achieved with either Pd0 or PdII catalysts. A variety of olefins and triarylphosphines are tolerated, and we inferred that both Pd0 and PdII could function directly without pre-oxidation or pre-reduction.
Organoselenium-catalyzed baeyer-villiger oxidation of α,β-unsaturated ketones by hydrogen peroxide to access vinyl esters
Zhang, Xu,Ye, Jianqing,Yu, Lei,Shi, Xinkang,Zhang, Ming,Xu, Qing,Lautens, Mark
supporting information, p. 955 - 960 (2015/03/30)
By carefully screening the organoselenium pre-catalysts and optimizing the reaction conditions, simple dibenzyl diselenide was found to be the best pre-catalyst for Baeyer-Villiger oxidation of (E)-α,β-unsaturated ketones with the green oxidant hydrogen peroxide at room temperature. The organoselenium catalyst used in this reaction could be recycled and reused several times. This new method was suitable not only for methyl unsaturated ketones, but also for alkyl and aryl unsaturated ketones. Therefore, it provided a direct, mild, practical, highly functional group-tolerant process for the chemoselective preparation of the versatile (E)-vinyl esters from the readily available (E)-α,β-unsaturated ketones. A possible mechanism was also proposed to rationalize the activity of the organoselenium catalyst in the presence of hydrogen peroxide in this Baeyer-Villiger oxidation reaction.
