2094-69-1Relevant articles and documents
A study of electronic effects on the kinetics of thermal deamination of N-nitrosoamides
Darbeau,Pease,Gibble
, p. 5027 - 5032 (2001)
N-4-R-Benzyl-N-nitrosopivalamides (1a-d; R = MeO, Me, H, NO2) were allowed to decompose at 18 °C in C6D12, CDCl3, CD3CN, and d6-DMSO, and the rates of decomposition were followed by 1H NMR spectroscopy. The half-lives of the nitrosoamides were found to vary in a systematic way with the nature of the R group on the aromatic nucleus. Electron-releasing groups were found to decrease the stability of the starting nitrosoamide, whereas electron-withdrawing ones increased the nitrosoamides' thermal stability. A Hammett-type plot of log(rate constants of deamination) vs σp was linear (R2 = 0.986) with a ρ-type value of -0.90 indicating development of significant positive charge at the benzylic position in the transition state of the rate-determining step. The thermal stability of the nitrosoamides was also found to be systematically affected by the polarity of the solvent: as the solvent polarity increased, so did the lability of the nitrosoamides. This observation of intra- and intermolecular electronic perturbations of the kinetics of nitrosoamide decomposition appears to be novel. A closer look at the rate-determining step of nitrosoamide thermolysis is made, and a mechanistic framework is proposed that accounts for both steric and electronic modulation of nitrosoamide stability as well as the greater thermal stabilities of the related N-nitrocarboxamides and N-nitrosotosylamides.
Nickel-catalyzed direct C-H/C-O cross couplings generating fluorobenzenes and heteroarenes
Xiao, Jing,Chen, Tieqiao,Han, Li-Biao
, p. 812 - 815 (2015)
The Ni-catalyzed direct C-H/C-O cross couplings of benzylic alcohol derivatives with fluorobenzenes and heteroarenes are disclosed. This transformation provides a straightforward and efficient method for the synthesis of these valuable heteroatom-containing compounds.
A solvent-reagent selection guide for Steglich-type esterification of carboxylic acids
Jordan, Andrew,Sneddon, Helen F.,Sydenham, Jack,Whymark, Kyran D.
supporting information, p. 6405 - 6413 (2021/09/10)
The Steglich esterification is a widely employed method for the formation of esters under mild conditions. A number of issues regarding the sustainability of this transformation have been identified, chiefly the use of hazardous carbodiimide coupling reagents in conjunction with solvents with considerable issues such as dichloromethane (DCM) and N,N-dimethylformamide (DMF). To overcome these issues, we have developed a solvent-reagent selection guide for the formation of esters via Steglich-type reactions with the aim of providing safer, more sustainable conditions. Optimum reaction conditions have been identified after high-throughput screening of solvent-reagent combinations, namely the use of Mukaiyama's reagent (Muk) in conjunction with solvent dimethyl carbonate (DMC). The new reaction conditions were also exemplified through the synthesis of a small selection of building-block like molecules and includes the formation of t-butyl esters.
Epoxide as precatalyst for metal-free catalytic transesterification
Tanaka, Shinji,Nakashima, Takuya,Satou,Oono, Hiromi,Kon, Yoshihiro,Tamura, Masanori,Sato, Kazuhiko
, p. 2009 - 2013 (2019/07/03)
Transesterification of methyl esters was accelerated by an in situ-generated metal-free catalyst comprising a quaternary alkylammonium salt and an epoxide. The combination of a quaternary alkylammonium acetate and glycidol is optimal, and various esters were synthesized from methyl esters with alcohols in good to excellent yield. Analysis of the catalyst solution revealed that basic species are generated by the ring-opening reaction of epoxide.
Visible light-induced transformation of aldehydes to esters, carboxylic anhydrides and amides
Gaspa, Silvia,Raposo, Inês,Pereira, Leonor,Mulas, Gabriele,Ricci, Pier Carlo,Porcheddu, Andrea,De Luca, Lidia
supporting information, p. 10711 - 10715 (2019/07/15)
A transition metal- and organophotocatalyst free synthesis of esters, carboxylic anhydrides and amides from aldehydes induced by visible-light has been reported. The proposed methodology can be carried out by the use of sunlight or artificial visible light as a blue LED source. The methodology has a very broad applicability and the desired products are obtained in very satisfactory yields.
Nickel-Catalyzed Benzylic Substitution of Benzyl Esters with Malonates as a Soft Carbon Nucleophile
Tsuji, Hiroaki,Hashimoto, Keisuke,Kawatsura, Motoi
supporting information, p. 8837 - 8841 (2019/11/11)
The nickel-catalyzed benzylic substitution of benzyl alcohol derivatives with a soft carbon nucleophile is extremely rare compared to that with a hard carbon nucleophile. We have achieved the nickel-catalyzed benzylic substitution of benzyl esters with malonates as a soft carbon nucleophile. Primary and secondary benzyl 2,3,4,5,6-pentafluorobenzoates as well as a wide variety of malonate derivatives were well tolerated in the nickel-catalyzed reaction, providing the corresponding alkylation products in 46-86% yields (34 examples). Additionally, we propose a possible reaction mechanism that would undergo via the ??1- A nd ??3-benzylnickel intermediates.
Sterically congested ester formation from α-substituted malononitrile and alcohol by an oxidative method using molecular oxygen
Hayashi, Yujiro,Li, Jing,Asano, Hirotaka,Sakamoto, Daisuke
supporting information, p. 675 - 677 (2018/11/23)
A metal-free oxidative esterification or thio-esterifica-tion of readily available substituted malononitrile and alcohol or thiol has been developed by simply mixing α-substituted malononitrile and alcohol or thiol in the presence of base under a molecular oxygen atmosphere. Sterically hindered ester or thioester can be prepared efficiently.
Reusable and efficient polyvinylpolypyrrolidone-supported triflic acid catalyst for acylation of alcohols, phenols, amines, and thiols under solvent-free conditions
Tajbakhsh, Mahgol,Tajbakhsh, Mahmoud,Khaksar, Samad,Gazvini, Helia Janatian,Heidary, Marzieh
, p. 1117 - 1122 (2017/05/10)
Abstract: A triflic acid-functionalized polyvinylpolypyrrolidone was prepared and fully characterized by FT-IR, TGA, and SEM. This super acidic solid catalyst shows high catalytic activity for selective acylation of alcohols, phenols, amines, and thiols with anhydrides under solvent-free conditions at room temperature. In addition, this method features an easy to handle solid super acid catalyst and an operationally simple procedure, affording the desired acylated products in excellent yields. Graphical abstract: [Figure not available: see fulltext.].
METHOD OF CONVERTING ALCOHOL TO HALIDE
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Page/Page column 50; 66; 67, (2017/01/02)
The present invention relates to a method of converting an alcohol into a corresponding halide. This method comprises reacting the alcohol with an optionally substituted aromatic carboxylic acid halide in presence of an N-substituted formamide to replace a hydroxyl group of the alcohol by a halogen atom. The present invention also relates to a method of converting an alcohol into a corresponding substitution product. The second method comprises: (a) performing the method of the invention of converting an alcohol into the corresponding halide; and (b) reacting the corresponding halide with a nucleophile to convert the halide into the nucleophilic substitution product.
Iodobenzene Dichloride in the Esterification and Amidation of Carboxylic Acids: In-Situ Synthesis of Ph3PCl2
Carle, Myriam S.,Shimokura, Grace K.,Murphy, Graham K.
, p. 3930 - 3933 (2016/08/24)
A novel, in-situ synthesis of dichlorotriphenylphosphorane (Ph3PCl2) is accomplished upon combining PPh3and the easily prepared hypervalent iodine reagent iodobenzene dichloride (PhICl2). The phosphorane is selectively generated in the presence of carboxylic acid or alcohol residues to rapidly produce acyl chlorides and alkyl chlorides in high yields. Addition of EtOH, PhOH, BnOH, Et2NH or CH2N2results in the direct synthesis of esters, amides and diazo ketones from carboxylic acids.
