Directed Additions of 2-Arylpyridines and Related Substrates to Cyclic Imines through Rhodium-Catalyzed C–H Functionalization

Abstract

Rhodium-catalyzed C-H functionalizations have been used for ortho-directed additions of 2-arylpyridines and (hetero)aryl-substituted pyrimidines, isoquinolines, and benzo[h]quinolones to cyclic imines. The resulting amino-functionalized products are formed in good to high yields.

Transition-Metal-Catalyzed C–H Bond Addition to Carbonyls, Imines, and Related Polarized π Bonds

“…88 A range of electron-rich and poor 2-arylpyridines were efficient coupling partners, and 2-(2-thiophenyl)pyridine and 2-(2-benzofuranyl)pyridine also coupled in good yield. N -Pyridyl and pyrimidyl indoles were also effective coupling partners.…”

Convergent Synthesis of α‐Branched Amines by Transition‐Metal‐Catalyzed C−H Bond Additions to Imines

“…In 2014, the Bolm laboratory published a strategy for Rh(III)‐catalyzed C−H additions to cyclic imines 26 (Scheme ) . Interestingly, in their evaluation of different metal catalysts the authors found that a cationic Ru(II) catalyst system also provided the desired addition product but in only moderate yield.…”

“…In 2014, the Bolm laboratory published a strategy for Rh(III)-catalyzed CÀH additions to cyclic imines 26 (Scheme 8). [13] Interestingly, in their evaluation of different metal catalysts the authors found that a cationic Ru(II) catalyst system also provided the desired addition product but in only moderate yield. Several heteroaromatic directing groups were effective for this transformation, including pyridine, pyrimidine and quinoline functionalities, and the functionalization of both aromatic and heteroaromatic CÀH bonds was demonstrated.…”

Rhodium(III)‐Catalyzed Three‐Component Reaction of Imines, Alkynes, and Aldehydes through CH Activation

“…[12] More importantly, this reaction provides a new methodology to access unusual complex building blocks for the preparation of diverse biologically active compounds (Scheme 1). [13] In an initial attempt, cyclic N-sulfonyl ketimine 1 a, benzaldehyde (2 a) and diphenyl acetylene (3 a) were tested under the early [3+2] reaction conditions. [11a] Despite good conversion regarding the A + B variant, we detected the A + B + C product 5 a, albeit in a very low yield (Table 1, entry 1).…”

“…Among other anhydrides screened, Ac 2 O and trifluoroacetic acid (TFAA) also proved to be appropriate for the reaction (Table 1, entries 9-11). However, varying the ratio of (Boc) 2 O only improved the yield of the two-component byproduct 4 a (Table 1, entries [12][13][14][15]. It is worth noting that other solvents, such as toluene, methanol, AcOH, and DMF, turned out to be ineffective for the MCR (Table 1, entries 16-19).…”