640-61-9Relevant academic research and scientific papers
Micellar Effects in the Acid Denitrosation of N-Nitroso-N-methyl-p-toluenesulfonamide
Bravo, Carlos,Herves, Pablo,Leis, J. Ramon,Pena, M. Elena
, p. 8816 - 8820 (1990)
The acid denitrosation of N-methyl-N-nitroso-p-toluenesulfonamide (MNTS) has been studied in the presence of anionic, cationic, and nonionic surfactants.Both cationic and nonionic micelles inhibit the reaction through an effective association of the substrate to the micellar pseudophase.This bound substrate becomes unreactive due to the absence of protons in the micellar Stern layer.The kinetic results allow a quantitative estimation of the association constants.The reaction has also been studied in the presence of anionic surfactants, both functionalized and nonfunctionalized.With hydrogen dodecyl sulfate, the reaction is accelerated by the presence of surfactant and reaches a limiting value at high concentrations.The reaction with sodium dodecyl sulfate shows a familiar pattern of behavior, with the reactivity passing through a maximum as the concentration of surfactant is increased.These facts can be quantitatively understood in terms of the pseudophase ion-exchange model, assuming a constancy in the degree of micellar fraction charge neutralized.Numerical values for the rate constants in the micellar pseudophase could be obtained and compared with those in water.Association constants between MNTS and micellar aggregates can also be obtained as well as the equilibrium exchange constants between Na+ and protons.The study of the system in the presence of added NaCl, KCl, and CsCl provided further test for the kinetic model as well as the estimation of other ion-exchange constants.
Ligand-Controlled Regiodivergence for Catalytic Stereoselective Semireduction of Allenamides
Hajiloo Shayegan, Mojtaba,Li, Zhong-Yuan,Cui, Xin
supporting information, (2021/12/02)
Ligand-controlled regiodivergence has been developed for catalytic semireduction of allenamides with excellent chemo- and stereocontrol. This system also provides an example of catalytic regiodivergent semireduction of allenes for the first time. The divergence of the semireduction is enabled by ligand switch with the same palladium pre-catalyst under operationally simple and mild conditions. Monodentate ligand XPhos exclusively promotes selective 1,2-semireduction to afford allylic amides, while bidentate ligand BINAP completely switched the regioselectivity to 2,3-semireduction, producing (E)-enamide derivatives.
Chemoselective Cleavage of Acylsulfonamides and Sulfonamides by Aluminum Halides
Sang, Dayong,Dong, Bingqian,Liu, Yunfeng,Tian, Juan
, p. 3586 - 3595 (2022/02/25)
The chemoselective cleavage of C-N bonds of amides, sulfonamides, and acylsulfonamides by aluminum halides is described. AlCl3and AlI3display complementary reactivities toward N-alkyl and N-acyl moieties. N-Alkylacylsulfonamides, sec
Visible-Light-Induced C4-Selective Functionalization of Pyridinium Salts with Cyclopropanols
Hong, Sungwoo,Kim, Taehwan,Vellakkaran, Mari
supporting information, (2021/11/27)
The site-selective C?H functionalization of heteroarenes is of considerable importance for streamlining the rapid modification of bioactive molecules. Herein, we report a general strategy for visible-light-induced β-carbonyl alkylation at the C4 position of pyridines with high site selectivity using various cyclopropanols and N-amidopyridinium salts. In this process, hydrogen-atom transfer between the generated sulfonamidyl radicals and O?H bonds of cyclopropanols generates β-carbonyl radicals, providing efficient access to synthetically valuable β-pyridylated (aryl)ketones, aldehydes, and esters with broad functional-group tolerance. In addition, the mild method serves as an effective tool for the site-selective late-stage functionalization of complex and medicinally relevant molecules.
N-Aroylsulfonamide-Photofragmentation (ASAP)-A Versatile Route to Biaryls
Wessig, Pablo,Krebs, Saskia
supporting information, p. 6367 - 6374 (2021/09/29)
The photochemical fragmentation of N-aroylsulfonamides 9 (ASAP) is a powerful method for the preparation of various biaryls. Compounds 9 are easily accessible in two steps from amines by treatment with arenesulfonyl chlorides and aroyl chlorides. Many of these compounds were prepared for the first time. The irradiation takes place in a previously developed continuous-flow reactor using inexpensive UVB or UVC fluorescent lamps. Isocyanates and sulphur dioxide are formed as the only by-products. The ASAP tolerates a variety of functional groups and is even suited for the preparation of phenylnaphthalenes and terphenyls. The ASAP mechanism was elucidated by interaction of photophysical and quantum chemical (DFT) methods and revealed a spirocyclic biradical as key intermediate.
Electrochemical C?H Amidation of Heteroarenes with N-Alkyl Sulfonamides in Aqueous Medium
Zhang, Yan,Lin, Zhipeng,Ackermann, Lutz
supporting information, p. 242 - 246 (2020/11/30)
The construction of C?N bonds by free radical reactions represents a powerful synthetic approach for direct C?H amidations of arenes or heteroarenes. Developing efficient and more environmentally friendly synthetic methods for C?H amidation reactions remains highly desirable. Herein, metal-free electrochemical oxidative dehydrogenative C?H amidations of heteroarenes with N-alkylsulfonamides have been accomplished. The catalyst- and chemical-oxidant-free C?H amidation features an ample scope and employs electricity as the green and sole oxidant. A variety of heteroarenes, including indoles, pyrroles, benzofuran and benzothiophene, thereby underwent this C(sp2)?H nitrogenation. Cyclic voltammetry studies and control experiments provided evidence for nitrogen-centered radicals being directly generated under metal-free electrocatalysis.
Cobalt-Catalyzed 1,4-Aryl Migration/Desulfonylation Cascade: Synthesis of α-Aryl Amides
Gillaizeau-Simonian, Nicolas,Barde, Etienne,Guérinot, Amandine,Cossy, Janine
supporting information, p. 4004 - 4008 (2021/02/11)
A cobalt-catalyzed 1,4-aryl migration/disulfonylation cascade applied to α-bromo N-sulfonyl amides was developed. The reaction was highly chemoselective, allowing the preparation of α-aryl amides possessing a variety of functional groups. The method was used as the key step to synthesize an alkaloid, (±)-deoxyeseroline. Mechanistic investigations suggest a radical process.
Recyclable covalent triazine framework-supported iridium catalyst for the N-methylation of amines with methanol in the presence of carbonate
Liu, Peng,Yang, Jiazhi,Ai, Yao,Hao, Shushu,Chen, Xiaozhong,Li, Feng
, p. 281 - 290 (2021/03/26)
An iridium complex Cp*Ir@CTF, which is synthesized by the coordinative immobilization of [Cp*IrCl2]2 on a functionalized covalent triazine framework (CTF), was found to be a general and highly efficient catalyst for the N-methylation of amines with methanol in the presence of carbonate. Under environmentally benign conditions, a variety of desirable products were obtained in high yields with complete selectivities and functional group friendliness. Furthermore, the synthesized catalyst could be recycled by simple filtration without obvious loss of catalytic activity after sixth cycle. Notably, this research exhibited the potential of covalent triazine framework-supported transition metal catalysts for hydrogen autotransfer process.
N-Methylation of Amines with Methanol in the Presence of Carbonate Salt Catalyzed by a Metal-Ligand Bifunctional Ruthenium Catalyst [(p-cymene)Ru(2,2′-bpyO)(H2O)]
Liu, Peng,Tung, Nguyen Thanh,Xu, Xiangchao,Yang, Jiazhi,Li, Feng
, p. 2621 - 2631 (2021/02/27)
A ruthenium complex [(p-cymene)Ru(2,2′-bpyO)(H2O)] was found to be a general and efficient catalyst for the N-methylation of amines with methanol in the presence of carbonate salt. Moreover, a series of sensitive substituents, such as nitro, ester, cyano, and vinyl groups, were tolerated under present conditions. It was confirmed that OH units in the ligand are crucial for the catalytic activity. Notably, this research exhibited the potential of metal-ligand bifunctional ruthenium catalysts for the hydrogen autotransfer process.
Additive-freeN-methylation of amines with methanol over supported iridium catalyst
Liu, Xiang,Loh, Teck-Peng,Qiang, Wenwen,Wang, Jing,Ye, Sen,Zhu, Longfei
, p. 3364 - 3375 (2021/06/06)
An efficient and versatile zinc oxide-supported iridium (Ir/ZnO) catalyst was developed to catalyze the additive-freeN-methylation of amines with methanol. Mechanistic studies suggested that the high catalytic reactivity is rooted in the small sizes (1.4 nm) of Ir nanoparticles and the high ratio (93%) of oxidized iridium species (IrOx, Ir3+and Ir4+) on the catalyst. Moreover, the delicate cooperation between the IrOxand ZnO support also promoted its high reactivity. The selectivity of this catalyticN-methylation was controllable between dimethylation and monomethylation by carefully tuning the catalyst loading and reaction solvent. Specifically, neat methanol with high catalyst loading (2 mol% Ir) favored the formation ofN,N-dimethylated amine, while the mesitylene/methanol mixture with low catalyst loading (0.5 mol% Ir) was prone to producing mono-N-methylated amines. An environmentally benign continuous flow system with a recycled mode was also developed for the efficient production ofN-methylated amines. With optimal flow rates and amine concentrations, a variety ofN-methylamines were produced with good to excellent yields in this Ir/ZnO-based flow system, providing a starting point for the clean and efficient production ofN-methylamines with this cost-effective chemical process.
