9004-78-8Relevant academic research and scientific papers
Diradicals Photogeneration from Chloroaryl-Substituted Carboxylic Acids
Di Terlizzi, Lorenzo,Protti, Stefano,Ravelli, Davide,Fagnoni, Maurizio
, (2022/04/09)
With the aim of generating new, thermally inaccessible diradicals, potentially able to induce a double-strand DNA cleavage, the photochemistry of a set of chloroaryl-substituted carboxylic acids in polar media was investigated. The photoheterolytic cleavage of the Ar?Cl bond occurred in each case to form the corresponding triplet phenyl cations. Under basic conditions, the photorelease of the chloride anion was accompanied by an intramolecular electron-transfer from the carboxylate group to the aromatic radical cationic site to give a diradical species. This latter intermediate could then undergo CO2 loss in a structure-dependent fashion, according to the stability of the resulting diradical, or abstract a hydrogen atom from the medium. In aqueous environment at physiological pH (pH=7.3), both a phenyl cation and a diradical chemistry was observed. The mechanistic scenario and the role of the various intermediates (aryl cations and diradicals) involved in the process was supported by computational analysis.
Me3SI-promoted chemoselective deacetylation: a general and mild protocol
Gurawa, Aakanksha,Kashyap, Sudhir,Kumar, Manoj
, p. 19310 - 19315 (2021/06/03)
A Me3SI-mediated simple and efficient protocol for the chemoselective deprotection of acetyl groups has been developedviaemploying KMnO4as an additive. This chemoselective deacetylation is amenable to a wide range of substrates, tolerating diverse and sensitive functional groups in carbohydrates, amino acids, natural products, heterocycles, and general scaffolds. The protocol is attractive because it uses an environmentally benign reagent system to perform quantitative and clean transformations under ambient conditions.
Novel Bis[N-alkyl-N-(2-diphenylphosphinylethyl)]diglycolamides: Synthesis and NMR Spectroscopy Studies
Bondarenko,Tcarkova,Belus’,Artyushin,Peregudov
, p. 181 - 189 (2021/03/20)
Abstract: Pentadentate bis[N-alkyl-N-(2-diphenylphosphinylethyl)]diglycolamides [Ph2P(O)CH2CH2N(R)· C(O)CH2]2O, where R Me, Bu, Oct, were synthesized by reaction of diglycolyl chloride with N-alkyl-N-(2-diphenylphosphinylethyl)amines Ph2P(O)CH2CH2NHR obtained by reacting diphenyl(2-phenoxyethyl)phosphine oxide with primary alkylamines in DMSO in the presence of an aqueous alkali. Structure of the prepared compounds was studied by 1H, 13C, and 31P NMR spectroscopy.
Development of effective bidentate diphosphine ligands of ruthenium catalysts toward practical hydrogenation of carboxylic acids
Saito, Susumu,Wen, Ke,Yoshioka, Shota
, p. 1510 - 1524 (2021/06/18)
Hydrogenation of carboxylic acids (CAs) to alcohols represents one of the most ideal reduction methods for utilizing abundant CAs as alternative carbon and energy sources. However, systematic studies on the effects of metal-to-ligand relationships on the catalytic activity of metal complex catalysts are scarce. We previously demonstrated a rational methodology for CA hydrogenation, in which CA-derived cationic metal carboxylate [(PP)M(OCOR)]+ (M = Ru and Re; P = one P coordination) served as the catalyst prototype for CA self-induced CA hydrogenation. Herein, we report systematic trial- and-error studies on how we could achieve higher catalytic activity by modifying the structure of bidentate diphosphine (PP) ligands of molecular Ru catalysts. Carbon chains connecting two P atoms as well as Ar groups substituted on the P atoms of PP ligands were intensively varied, and the induction of active Ru catalysts from precatalyst Ru(acac)3 was surveyed extensively. As a result, the activity and durability of the (PP)Ru catalyst substantially increased compared to those of other molecular Ru catalyst systems, including our original Ru catalysts. The results validate our approach for improving the catalyst performance, which would benefit further advancement of CA self-induced CA hydrogenation.
Electrophotocatalytic C?H Heterofunctionalization of Arenes
Huang, He,Lambert, Tristan H.
supporting information, p. 11163 - 11167 (2021/04/19)
The electrophotocatalytic heterofunctionalization of arenes is described. Using 2,3-dichloro-5,6-dicyanoquinone (DDQ) under a mild electrochemical potential with visible-light irradiation, arenes undergo oxidant-free hydroxylation, alkoxylation, and amination with high chemoselectivity. In addition to batch reactions, an electrophotocatalytic recirculating flow process is demonstrated, enabling the conversion of benzene to phenol on a gram scale.
Ligand-Free Copper-Catalyzed Ullmann-Type C?O Bond Formation in Non-Innocent Deep Eutectic Solvents under Aerobic Conditions
Capriati, Vito,García-álvarez, Joaquín,Marinò, Manuela,Perna, Filippo M.,Quivelli, Andrea Francesca,Vitale, Paola
, (2021/12/09)
An efficient and novel protocol was developed for a Cu-catalyzed Ullmann-type aryl alkyl ether synthesis by reacting various (hetero)aryl halides (Cl, Br, I) with alcohols as active components of environmentally benign choline chloride-based eutectic mixtures. Under optimized conditions, the reaction proceeded under mild conditions (80 °C) in air, in the absence of additional ligands, with a catalyst [CuI or CuII species] loading up to 5 mol% and K2CO3 as the base, providing the desired aryloxy derivatives in up to 98 % yield. The potential application of the methodology was demonstrated in the valorization of cheap, easily available, and naturally occurring polyols (e. g., glycerol) for the synthesis of some pharmacologically active aryloxypropanediols (Guaiphenesin, Mephenesin, and Chlorphenesin) on a 2 g scale in 70–96 % yield. Catalyst, base, and deep eutectic solvent could easily and successfully be recycled up to seven times with an E-factor as low as 5.76.
KMnO4-catalyzed chemoselective deprotection of acetate and controllable deacetylation-oxidation in one pot
Gurawa, Aakanksha,Kumar, Manoj,Rao, Dodla S.,Kashyap, Sudhir
supporting information, p. 16702 - 16707 (2020/10/27)
A novel and efficient protocol for chemoselective deacetylation under ambient conditions was developed using catalytic KMnO4. The stoichiometric use of KMnO4 highlighted the dual role of a heterogeneous oxidant enabling direct access to aromatic aldehydes in one-pot sequential deacetylation-oxidation. The reaction employed an alternative solvent system and allowed the clean transformation of benzyl acetate to sensitive aldehyde in a single step while preventing over-oxidation to acids. Use of inexpensive and readily accessible KMnO4 as an environmentally benign reagent and the ease of the reaction operation were particularly attractive, and enabled the controlled oxidation and facile cleavage of acetate in a preceding step. This journal is
Drastic fluorine effect: Complete reversal of the selectivity in the Au-catalyzed hydroalkoxylation reaction of fluorinated haloalkynes
Cloutier, Mélissa,Mamone, Marius,Paquin, Jean-Fran?ois
supporting information, p. 5969 - 5972 (2020/06/04)
The gold-catalyzed hydration reaction of haloalkynes is highly regioselective producing 2-halomethylketones as the sole products. Herein, we document a drastic fluorine effect where the reaction of 1-halo-3,3-difluoroalkynes as substrates leads to a complete reversal of selectivity and produces 3,3-difluoroesters as the unique products.
Base- A nd Catalyst-Induced Orthogonal Site Selectivities in Acylation of Amphiphilic Diols
Ashush, Natali,Dobrovetsky, Roman,Fallek, Amit,Fallek, Reut,Portnoy, Moshe
supporting information, (2020/05/25)
Seeking to selectively functionalize natural and synthetic amphiphiles, we explored acylation of model amphiphilic diols. The use of a nucleophilic catalyst enabled a remarkable shift of the site selectivity from the polar site, preferred in background noncatalyzed or base-promoted reactions, to the apolar site. This tendency was significantly enhanced for organocatalysts comprising an imidazole active site surrounded by long/branched tails. An explanation of these orthogonal modes of selectivity is supported by competitive experiments with monoalcohol substrates.
Synthetic and Mechanistic Studies on 2,3-Dihydrobenzo[ b ][1,4]-oxaselenines Formation from Selenocyanates
Bonesi, Sergio M.,Cattaneo, Mauricio,Chao, María N.,Rodriguez, Juan B.,Sanchez Gonzalez, Jonathan,Szajnman, Sergio H.
, p. 1643 - 1658 (2020/05/25)
An expedient preparation of selenium-containing hetero-cycles via an m -chloroperbenzoic acid-mediated seleno-annulation starting from selenocyanate derivatives is described. In spite of its significance, this cyclization reaction is virtually understudied not only from the point of view of its scope, but also from the mechanistic aspects associated to this remarkable transformation. In this sense, several selenocyanate and thiocyanate derivatives bearing an aromatic ring were evaluated as substrates under different reaction conditions of this interesting cyclization yielding important insights on its scope as well as relevant information on the reaction mechanism.
