4138-22-1Relevant academic research and scientific papers
Xanthate-Mediated Incorporation of Quaternary Centers into Heteroarenes
Revil-Baudard, Vincent L.,Vors, Jean-Pierre,Zard, Samir Z.
supporting information, p. 3531 - 3535 (2018/06/26)
The xanthate-mediated addition of tertiary alkyl radicals to heteroarenes enabled the easy functionalization of heteroaromatic rings as well as more decorated structures, such as marketed drugs or agrochemicals. This work provides a synthetic tool for efficiently exploring the chemical space by allowing late-stage diversification with a high tolerance toward functional groups.
Metal-free C-H alkylation of heteroarenes with alkyltrifluoroborates: A general protocol for 1°, 2° and 3° alkylation
Matsui, Jennifer K.,Primer, David N.,Molander, Gary A.
, p. 3512 - 3522 (2017/07/10)
A photoredox-catalyzed C-H functionalization of heteroarenes using a variety of primary, secondary, and tertiary alkyltrifluoroborates is reported. Using Fukuzumi's organophotocatalyst and a mild oxidant, conditions amenable for functionalizing complex heteroaromatics are described, providing a valuable tool for late-stage derivatization. The reported method addresses the three major limitations of previously reported photoredox-mediated Minisci reactions: (1) use of superstoichiometric amounts of a radical precursor, (2) capricious regioselectivity, and (3) incorporation of expensive photocatalysts. Additionally, a number of unprecedented, complex alkyl radicals are used, thereby increasing the chemical space accessible to Minisci chemistry. To showcase the application in late-stage functionalization, quinine and camptothecin analogues were synthesized. Finally, NMR studies were conducted to provide a rationalization for the heteroaryl activation that permits the use of a single equivalent of radical precursor and also leads to enhanced regioselectivity. Thus, by 1H and 13C NMR a distinct heteroaryl species was observed in the presence of acid catalyst and BF3.
Modification of Pyridine-3-carboxamide (Nicotinamide) by Radical Substitution
Tada, Masaru,Yokoi, Yurie
, p. 45 - 48 (2007/10/02)
Pyridine-3-carboxamide (1) was reacted with alkyl radicals to give mono-, di-, and tri-alkylated products.The t-butyl radical gives only 6-t-butylpyridine-3-carboxamide (4a).The reactivity decreases in the order of t-butyl, isopropyl, and ethyl radicals.The product 4a reacts further with the 2-phthalimidoethyl radical to give 2- and 4-substituted products 9 and 10, which were transformed into tetrahydronaphthyridinone derivatives 11 and 12.
