73086-84-7Relevant articles and documents
Visible-Light-Induced Regioselective Deaminative Alkylation of Coumarins via Photoredox Catalysis
Tao, Maoling,Wang, An-Jun,Guo, Peng,Li, Weipiao,Zhao, Liang,Tong, Jie,Wang, Haoyang,Yu, Yanbo,He, Chun-Yang
supporting information, p. 24 - 29 (2021/10/19)
3-Alkylated coumarins have many applications in medicinal chemistry, however, methods access to such structures are still limited. Herein, we report a site-selective photocatalytic deaminative alkylation of coumarins utilizing pyridinium-activated aliphatic primary amines as alkylation reagents. The protocol was highlighted by its mild reaction conditions, operational simplicity, and broad functional group compatibility. Moreover, this strategy enables late-stage modification of some pharmaceuticals and natural products, thus providing an appealing approach to valuable molecules in medicinal chemistry. (Figure presented.).
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.
Continuous-Flow Synthesis of Pyrylium Tetrafluoroborates: Application to Synthesis of Katritzky Salts and Photoinduced Cationic RAFT Polymerization
Sambiagio, Carlo,Ferrari, Matteo,Van Beurden, Koen,Ca', Nicola Della,Van Schijndel, Jack,Noel, Timothy
supporting information, p. 2042 - 2047 (2021/04/05)
Katritzky salts have emerged as effective alkyl radical sources upon metal- or photocatalysis. These are typically prepared from the corresponding triarylpyrylium ions, in turn an important class of photocatalysts for small molecules synthesis and photopolymerization. Here, a flow method for the rapid synthesis of both pyrylium and Katrizky salts in a telescoped fashion is reported. Moreover, several pyrylium salts were tested in the photoinduced RAFT polymerization of vinyl ethers under flow and batch conditions.
Visible-Light-Induced Deaminative Alkylation/Cyclization of Alkyl Amines with N-Methacryloyl-2-phenylbenzoimidazoles in Continuous-Flow Organo-Photocatalysis
Ramesh, Vankudoth,Gangadhar, Maram,Nanubolu, Jagadeesh Babu,Adiyala, Praveen Reddy
supporting information, p. 12908 - 12921 (2021/09/18)
Herein, we present a metal-free visible-light-induced eosin-y-catalyzed deaminative strategy for the sequential alkylation/cyclization of N-methacryloyl-2-phenylbenzoimidazoles with alkyl amine-derived Katritzky salts, which provides an efficient avenue for the construction of various benzo[4,5]imidazo[2,1-a]isoquinolin-6(5H)-one derivatives in moderate to excellent yields under mild reaction conditions. The key enabling feature of this novel reaction includes utilization of redox-active pyridinium salts from abundant and inexpensive primary amine feedstocks that were converted into alkyl radicals via C-N bond scission and subsequent alkylation/cyclization with N-methacryloyl-2-phenylbenzoimidazoles by the formation of two new C-C bonds. In addition, we implemented this protocol for a variety of amino acids, affording the products in moderate yields. Moreover, the novel, environmentally benign batch protocol was further carried out in a continuous-flow regime by utilizing a perfluoroalkoxy alkane tubing microreactor under optimized reaction conditions with a blue light-emitting diode light source, enabling excellent yields and a shorter reaction time (19 min) versus the long reaction time (16 h) of the batch reaction. The reaction displays excellent functional group tolerance, easy operation, scalability, mild reaction conditions, and broad synthetic utility.
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.
Deaminative Reductive Cross-Electrophile Couplings of Alkylpyridinium Salts and Aryl Bromides
Liao, Jennie,Basch, Corey H.,Hoerrner, Megan E.,Talley, Michael R.,Boscoe, Brian P.,Tucker, Joseph W.,Garnsey, Michelle R.,Watson, Mary P.
supporting information, p. 2941 - 2946 (2019/04/30)
A nickel-catalyzed reductive cross-coupling of alkylpyridinium salts and aryl bromides has been developed using Mn as the reductant. Both primary and secondary alkylpyridinium salts can be used, and high functional group and heterocycle tolerance is observed, including for protic groups. Mechanistic studies indicate the formation of an alkyl radical, and controlling its fate was key to the success of this reaction.
Engaging Alkenes and Alkynes in Deaminative Alkyl-Alkyl and Alkyl-Vinyl Cross-Couplings of Alkylpyridinium Salts
Baker, Kristen M.,Lucas Baca, Diana,Plunkett, Shane,Daneker, Mitchell E.,Watson, Mary P.
supporting information, p. 9738 - 9741 (2019/12/02)
An alkyl-alkyl cross-coupling of Katritzky alkylpyridinium salts and organoboranes, formed in situ via hydroboration of alkenes, has been developed. This method utilizes the abundance of both alkyl amine precursors and alkenes to form C(sp3)-C(sp3) bonds. This strategy is also effective with alkynes, enabling a C(sp3)-C(sp2) cross-coupling. Under these mild conditions, a broad range of functional groups, including protic groups, is tolerated. As seen with previous alkylpyridinium cross-couplings, mechanistic studies support an alkyl radical intermediate.
Deaminative Strategy for the Visible-Light-Mediated Generation of Alkyl Radicals
Klauck, Felix J. R.,James, Michael J.,Glorius, Frank
supporting information, p. 12336 - 12339 (2017/09/06)
A deaminative strategy for the visible-light-mediated generation of alkyl radicals from redox-activated primary amine precursors is described. Abundant and inexpensive primary amine feedstocks, including amino acids, were converted in a single step into redox-active pyridinium salts and subsequently into alkyl radicals by reaction with an excited-state photocatalyst. The broad synthetic potential of this protocol was demonstrated by the alkylation of a number of heteroarenes under mild conditions.
Alkylation of Monosubstituted Malonate Anions With Pyridinium and Quinolinium Salts
Katritzky, Alan R.,Aurrecoechea, Jose M.
, p. 342 - 345 (2007/10/02)
Monosubstituted malonate anions are alkylated at room temperature with 1-(sec-alkyl)quinolinium salts.Hindered disubstituted malonate esters can thus be prepared under very mild conditions.
Kinetics and Mechanism of Nucleophilic Displacements with Heterocycles as Leaving Groups. Part 10. Reactions of s-Alkyl Primary Amines with Pyryliums
Katritzky, Alan R.,Marquet, Jorge,Lloyd, Jeremy M.,Keay, James G.
, p. 1435 - 1442 (2007/10/02)
2,4,6-Triphenylpyrylium with s-alkylamines gives isolatable pyridiniums (which undergo SN2 substitution with nucleophiles and elimination to olefins). 2,4,6-triphenylpyrilium with 1-phenylethylamine and α-phenylbenzylamine forms the corresponding carbonium ions which may be trapped by nucleophiles.Isolated 1-cycloalkylbenzoquinoliniums (2) solvolyse by the SN1 mechanism (for five-, six- and seven-membered rings): for the cyclobutyl case an Sn2 reaction is also found.
