Synthesis of Indolines and Tetrahydroisoquinolines from Arylethylamines by Pd^II‐Catalyzed CH Activation Reactions

Abstract

Hand in hand: A versatile CH activation route for the synthesis of indolines, tetrahydroquinolines, and tetrahydroisoquinolines from simple arylethylamines relies on a one‐pot iodination and amination reaction (see scheme, Tf=trifluoromethanesulfonyl). The natural amino acids phenylalanine, tyrosine, and tryptophan can be converted into various heterocycles by using this technology.

Silver-catalysed direct amination of unactivated C–H bonds of functionalized molecules

“…Primary C-H bonds could be accessed only in cases of conformational bias 38,39 . To approach the primary selectivity of direct amination, Chen and Daugulis groups successfully developed a Pd-catalysed cyclization to specific ring systems by using a directing strategy while the manipulation of protecting group by multistep transformations limited its applications [40][41][42] To achieve the primary selectivity to construct the abundant five-membered heterocyclic products from easily available amine derivatives without the requirement of complicated directing groups, new strategies and new catalytic systems are highly desirable 43,44 . Notably, the compatibility with an array of the functionalities, the availability of the starting materials and the reliability of the new reaction system are important for potential applications.…”

Recent Advances on Transition-Metal-Catalyzed Halogenation of Unactivated C-H Bonds

“…另外, 以恶唑啉为导向基团, 也可以实现 六元环或者七元环过渡态的远程碘代反应 [26] (图 7, 式 2). 随后, Yu 课题组 [27,28] 进一步将反应体系进行拓展, 实现了羧基(图 8, 式 1)、三氟甲磺酰胺(NHTf) [29] (图 8, 式 2)、单齿配位酰胺(CONHAr F ) [30] (图 8, 式 3)的导向的 Figure 7 Pd(II)-catalyzed C-H iodination directed by oxazoline [33] (图 9, 式 2).…”

Transition Metal‐Catalyzed Formation of N‐Heterocycles via Aryl‐ or Vinyl C–H Bond Amination

“…Using either the one-electron oxidant Ce(SO 4 ) 2 or the two-electron oxidant N-fluoropyridinium 94, they reported that β-arylethylamines could be transformed to indolines in the presence of 10 mol-% palladium acetate (Scheme 24). [48] Improved yields, and functional group tolerance, and excellent regioselectivities, were observed when N-fluoropyridinium 94 was used as the oxidant. The Yu group reported that using other oxidants, such as phenyliodide diacetate or N-halosuccinimides, led to undesired by-products where acetylation or halogenation on the arene occurred instead of C-H bond amination.…”