1016990-41-2Relevant academic research and scientific papers
Hydroheteroarylation of Unactivated Alkenes Using N-Methoxyheteroarenium Salts
Ma, Xiaoshen,Dang, Hester,Rose, John A.,Rablen, Paul,Herzon, Seth B.
, p. 5998 - 6007 (2017/05/04)
We report the first reductive coupling of unactivated alkenes with N-methoxy pyridazinium, imidazolium, quinolinium, and isoquinolinium salts under hydrogen atom transfer (HAT) conditions, and an expanded scope for the coupling of alkenes with N-methoxy pyridinium salts. N-Methoxy pyridazinium, imidazolium, quinolinium, and isoquinolinium salts are accessible in 1-2 steps from the commercial arenes or arene N-oxides (25-99%). N-Methoxy imidazolium salts are accessible in three steps from commercial amines (50-85%). In total 36 discrete methoxyheteroarenium salts bearing electron-donating, electron-withdrawing, alkyl, aryl, halogen, and haloalkyl substituents were prepared (several in multigram quantities) and coupled with 38 different alkenes. The transformations proceed under neutral conditions at ambient temperature, provide monoalkylation products exclusively, and form a single alkene addition regioisomer. Preparatively useful and complementary site selectivities in the addition of secondary and tertiary radicals to pyidinium salts are documented: harder secondary radicals favor C-2 addition (2->10:1), while softer tertiary radicals favor bond formation to C-4 (4.7->29:1). A diene possessing a 1,2-disubstituted and 2,2-disubstituted alkene undergoes hydropyridylation at the latter exclusively (61%) suggesting useful site selectivities can be obtained in polyene substrates. The methoxypyridinium salts can also be employed in dehydrogenative arylation, borono-Minisci, and tandem arylation processes. Mechanistic studies support the involvement of a radical process.
Copper-catalyzed direct amination of 1,2,3-triazole N-oxides by C-H activation and C-N coupling
Zhu, Jiayi,Kong, Yubo,Lin, Feng,Wang, Baoshuang,Chen, Zhengwang,Liu, Liangxian
, p. 1507 - 1515 (2015/03/04)
An efficient approach for the synthesis of 4-amino-2-aryl- 1,2,3-triazole derivatives has been developed through the copper-catalyzed direct C-H amination of 2-aryl-1,2,3-triazole N-oxides under mild reaction conditions. Various amines, including primary and secondary aliphatic and aromatic amines, can be employed as effective coupling partners. The general performance of our method was also demonstrated by the oxidative amination of thiazole and imidazole N-oxides.
C2, C5, and C4 azole N-oxide direct arylation including room-temperature reactions
Campeau, Louis-Charles,Bertrand-Laperle, Megan,Leclerc, Jean-Philippe,Villemure, Elisia,Gorelsky, Serge,Fagnou, Keith
, p. 3276 - 3277 (2008/10/09)
The N-oxide group imparts a dramatic increase in reactivity at all positions of the azole ring of thiazoles and imidazoles and changes the weak bias for C5 > C2 arylation to a reliable C2 > C5 > C4 reactivity profile. Use of this cross-coupling strategy enables high yielding and room-temperature C2 arylations, mild reactions at C5, and the first examples of C4 arylation-providing a unique opportunity for exhaustive functionalization of the azole core with complete control of regioselectivity. A correlation of reactivity with the relative contributions of each carbon atom to the HOMO is observed and discussed. Copyright
