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.
Chemoselective Electrosynthesis Using Rapid Alternating Polarity
Baran, Phil S.,Carlson, Ethan,Edwards, Jacob T.,Hayashi, Kyohei,Kawamata, Yu,Saito, Masato,Shaji, Shobin,Simmons, Bryan J.,Waldmann, Dirk,Zapf, Christoph W.
supporting information, p. 16580 - 16588 (2021/10/20)
Challenges in the selective manipulation of functional groups (chemoselectivity) in organic synthesis have historically been overcome either by using reagents/catalysts that tunably interact with a substrate or through modification to shield undesired sites of reactivity (protecting groups). Although electrochemistry offers precise redox control to achieve unique chemoselectivity, this approach often becomes challenging in the presence of multiple redox-active functionalities. Historically, electrosynthesis has been performed almost solely by using direct current (DC). In contrast, applying alternating current (AC) has been known to change reaction outcomes considerably on an analytical scale but has rarely been strategically exploited for use in complex preparative organic synthesis. Here we show how a square waveform employed to deliver electric current - rapid alternating polarity (rAP) - enables control over reaction outcomes in the chemoselective reduction of carbonyl compounds, one of the most widely used reaction manifolds. The reactivity observed cannot be recapitulated using DC electrolysis or chemical reagents. The synthetic value brought by this new method for controlling chemoselectivity is vividly demonstrated in the context of classical reactivity problems such as chiral auxiliary removal and cutting-edge medicinal chemistry topics such as the synthesis of PROTACs.
Nickel/Photoredox Dual Catalytic Cross-Coupling of Alkyl and Amidyl Radicals to Construct C(sp3)-N Bonds
Zhou, Shaofang,Lv, Kang,Fu, Rui,Zhu, Changlei,Bao, Xiaoguang
, p. 5026 - 5034 (2021/05/07)
The construction of C(sp3)-N bonds via direct radical-radical cross-coupling under benign conditions is a desirable but challenging approach. Herein, the cross-coupling of alkyl and amidyl radicals to build aliphatic C-N bonds in a concise, mild, and oxid
Copper-catalyzed oxidative methylation of sulfonamides by dicumyl peroxide
Che, Shiying,Zhu, Qiao,Luo, Zhenghong,Lian, Yan,Zhao, Zijian
, p. 935 - 942 (2021/01/05)
A novel and facile copper-catalyzed methylation of sulfonamides was herein demonstrated. The practical transformation took place readily under the oxidative conditions, and N-methyl amides (23 examples) were successfully furnished in high efficiency (up to 90% yields). Dicumyl peroxide was considered to act not only as the oxidant in the system, but also methyl donor for the methylation protocol.
