71017-75-9Relevant academic research and scientific papers
Sulfinates from Amines: A Radical Approach to Alkyl Sulfonyl Derivatives via Donor-Acceptor Activation of Pyridinium Salts
Andrews, Jonathan A.,Pantaine, Lo?c R. E.,Palmer, Christopher F.,Poole, Darren L.,Willis, Michael C.
supporting information, p. 8488 - 8493 (2021/11/01)
Synthetically versatile alkyl sulfinates can be prepared from readily available amines, using Katritzky pyridinium salt intermediates. In a catalyst-free procedure, primary, secondary, and benzylic alkyl radicals are generated by photoinduced or thermally induced single-electron transfer (SET) from an electron donor-acceptor (EDA) complex, and trapped by SO2 to generate sulfonyl radicals. Hydrogen atom transfer (HAT) from Hantzsch ester gives alkyl sulfinate products, which are used to prepare a selection of medicinal chemistry relevant sulfonyl-containing motifs.
Tunable and Practical Homogeneous Organic Reductants for Cross-Electrophile Coupling
Barth, Emily L.,Charboneau, David J.,Germe, Cameron C.,Hazari, Nilay,Huang, Haotian,Mercado, Brandon Q.,Uehling, Mycah R.,Zultanski, Susan L.
supporting information, p. 21024 - 21036 (2021/12/14)
The syntheses of four new tunable homogeneous organic reductants based on a tetraaminoethylene scaffold are reported. The new reductants have enhanced air stability compared to current homogeneous reductants for metal-mediated reductive transformations, such as cross-electrophile coupling (XEC), and are solids at room temperature. In particular, the weakest reductant is indefinitely stable in air and has a reduction potential of -0.85 V versus ferrocene, which is significantly milder than conventional reductants used in XEC. All of the new reductants can facilitate C(sp2)-C(sp3) Ni-catalyzed XEC reactions and are compatible with complex substrates that are relevant to medicinal chemistry. The reductants span a range of nearly 0.5 V in reduction potential, which allows for control over the rate of electron transfer events in XEC. Specifically, we report a new strategy for controlled alkyl radical generation in Ni-catalyzed C(sp2)-C(sp3) XEC. The key to our approach is to tune the rate of alkyl radical generation from Katritzky salts, which liberate alkyl radicals upon single electron reduction, by varying the redox potentials of the reductant and Katritzky salt utilized in catalysis. Using our method, we perform XEC reactions between benzylic Katritzky salts and aryl halides. The method tolerates a variety of functional groups, some of which are particularly challenging for most XEC transformations. Overall, we expect that our new reductants will both replace conventional homogeneous reductants in current reductive transformations due to their stability and relatively facile synthesis and lead to the development of novel synthetic methods due to their tunability.
C-H Alkylation of Aldehydes by Merging TBADT Hydrogen Atom Transfer with Nickel Catalysis
Murugesan, Vetrivelan,Ganguly, Anirban,Karthika, Ardra,Rasappan, Ramesh
supporting information, p. 5389 - 5393 (2021/07/21)
Catalyst controlled site-selective C-H functionalization is a challenging but powerful tool in organic synthesis. Polarity-matched and sterically controlled hydrogen atom transfer (HAT) provides an excellent opportunity for site-selective functionalization. As such, the dual Ni/photoredox system was successfully employed to generate acyl radicals from aldehydes via selective formyl C-H activation and subsequently cross-coupled to generate ketones, a ubiquitous structural motif present in the vast majority of natural and bioactive molecules. However, only a handful of examples that are constrained to the use of aryl halides are developed. Given the wide availability of amines, we developed a cross-coupling reaction via C-N bond cleavage using the economic nickel and TBADT catalyst for the first time. A range of alkyl and aryl aldehydes were cross-coupled with benzylic and allylic pyridinium salts to afford ketones with a broad spectrum of functional group tolerance. High regioselectivity toward formyl C-H bonds even in the presence of α-methylene carbonyl or α-amino/oxy methylene was obtained.
Photocatalytic deaminative benzylation and alkylation of tetrahydroisoquinolines with N-alkylpyrydinium salts
No?l, Timothy,Sambiagio, Carlo,Sch?nbauer, David,Schnürch, Michael
, p. 809 - 817 (2020/05/18)
A ruthenium-catalyzed photoredox coupling of substituted N-aryltetrahydroisoquinolines (THIQs) and different bench-stable pyridinium salts was successfully developed to give fast access to 1-benzyl-THIQs. Furthermore, secondary alkyl and allyl groups were also successfully introduced via the same method. Additionally, the typically applied N-phenyl group in the THIQ substrate could be replaced by the cleavable p-methoxyphenyl (PMP) group and successful N-deprotection was demonstrated.
Nickel-Catalyzed Cross-Coupling of Alkyl Carboxylic Acid Derivatives with Pyridinium Salts via C-N Bond Cleavage
Pulikottil, Feba Thomas,Pilli, Ramadevi,Suku, Rohith Valavil,Rasappan, Ramesh
supporting information, p. 2902 - 2907 (2020/04/09)
The electrophile-electrophile cross-coupling of carboxylic acid derivatives and alkylpyridinium salts via C-N bond cleavage is developed. The method is distinguished by its simplicity and steers us through a variety of functionalized ketones in good to excellent yields. Besides acid chlorides, carboxylic acids were also employed as acylating agents, which enabled us to incorporate acid-sensitive functional groups such as MOM, BOC, and acetal. Control experiments with TEMPO revealed a radical pathway.
Rapid Assessment of the Reaction-Condition-Based Sensitivity of Chemical Transformations
Pitzer, Lena,Sch?fers, Felix,Glorius, Frank
supporting information, p. 8572 - 8576 (2019/05/28)
A systematic, user-friendly assessment tool that delivers a clear overview of the sensitivity of reactions to key parameters is highly desirable. Herein, the development of such a method is described. The intuitive, standardized presentation of the result
Deaminative Borylation of Aliphatic Amines Enabled by Visible Light Excitation of an Electron Donor–Acceptor Complex
Sandfort, Frederik,Strieth-Kalthoff, Felix,Klauck, Felix J. R.,James, Michael J.,Glorius, Frank
supporting information, p. 17210 - 17214 (2018/11/10)
A deaminative strategy for the borylation of aliphatic primary amines is described. Alkyl radicals derived from the single-electron reduction of redox-active pyridinium salts, which can be isolated or generated in situ, were borylated in a visible light-mediated reaction with bis(catecholato)diboron. No catalyst or further additives were required. The key electron donor–acceptor complex was characterized in detail by both experimental and computational investigations. The synthetic potential of this mild protocol was demonstrated through the late-stage functionalization of natural products and drug molecules.
Kinetics and mechanism of nucleophilic displacements with heterocycles as leaving groups. Part 23. Studies at the borderlines between reactions proceeding (i) via free carbocations, (ii) via rate-determining formation of ion-molecule pairs, and (iii) via rate-determining nucleophilic ...
Katritzky, Alan R.,Brycki, Bogumil
, p. 1161 - 1169 (2007/10/02)
Evidenece is presented to demonstrate that at the borderline between first order reaction via the formation of free carbocations, both mechanism proceed independently, without merging.Similarly at the borderline between first-order (rate determining formation) and second-order (rate-determining nucleophilic attack) rections of intimate ion-molecule pairs, both reactions again proceed independently.
The Preparation of Primary Alkyl and Benzyl Fluorides from the Corresponding Primary Amines
Katritzky, Alan R.,Patel, Ranjan C.
, p. 2901 - 2903 (2007/10/02)
N-substituted 2,4,6-triphenylpyridinium fluorides (in contrast to these and other tetrafluoroborates) thermolyse to the corresponding primary alkyl and benzyl fluorides.The pyridinium fluorides are made from 2,4,6-triphenylpyrylium fluoride and the relevant amine.
