22253-59-4Relevant articles and documents
Cambiarenes: Single-Step Synthesis and Selective Zwitterion Binding of a Clip-Shaped Macrocycle with a Redox-Active Core
Petersen, Riley J.,Rozeboom, Brett J.,Oburn, Shalisa M.,Blythe, Nolan J.,Rathje, Tanner L.,Luna, Javier A.,Kibby, Steven K.,O'Brien, Emily A.,Rohr, Kayleigh G.,Carpenter, Joshua R.,Sanders, Taylor L.,Johnson, Andrew M.,Hutchins, Kristin M.,Shaw, Scott K.,MacGillivray, Leonard R.,Wackerly, Jay Wm.
, p. 1928 - 1930 (2020)
A novel macrocyclic host molecule was synthesized that forms in a single step from commercially available starting materials. The core of the macrocycle backbone possesses two quinone rings and, thus, it is redox-active. Host–guest binding involving the clip-shaped cavity indicates selective binding of pyridine N-oxides based on the electron density of and steric bulk around the anionic oxygen.
Convenient approaches to 4-trifluoromethylpyridine
Jiang, Biao,Xiong, Wennan,Zhang, Xiaobing,Zhang, Fangjiang
, p. 531 - 534 (2001)
A number of approaches to the synthesis of 2-chloro-and 2,6-dichloro-4-trifluoromethylpyridine are described. The first method for 2-chloro-and 2,6-dichloro-4-trifluoromethylpyridine is based on commercially available ethyl trifluoroacetate. An alternative access to 2,6-dichloro-4-trifluoromethyl pyridine uses trifluoroacetaldehyde as starting material. 2-Chloro-4-trifluoromethylpyridine is prepared from ethyl(trifluoroacetylvinyl)ether in two steps.
Visible-Light-Induced ortho-Selective Migration on Pyridyl Ring: Trifluoromethylative Pyridylation of Unactivated Alkenes
Jeon, Jinwon,He, Yu-Tao,Shin, Sanghoon,Hong, Sungwoo
supporting information, p. 281 - 285 (2019/11/26)
The photocatalyzed ortho-selective migration on a pyridyl ring has been achieved for the site-selective trifluoromethylative pyridylation of unactivated alkenes. The overall process is initiated by the selective addition of a CF3 radical to the alkene to provide a nucleophilic alkyl radical intermediate, which enables an intramolecular endo addition exclusively to the ortho-position of the pyridinium salt. Both secondary and tertiary alkyl radicals are well-suited for addition to the C2-position of pyridinium salts to ultimately provide synthetically valuable C2-fluoroalkyl functionalized pyridines. Moreover, the method was successfully applied to the reaction with P-centered radicals. The utility of this transformation was further demonstrated by the late-stage functionalization of complex bioactive molecules.
Hydroheteroarylation of Unactivated Alkenes Using N-Methoxyheteroarenium Salts
Ma, Xiaoshen,Dang, Hester,Rose, John A.,Rablen, Paul,Herzon, Seth B.
supporting information, 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.
