Site Selective Synthesis of Pentaarylpyridines via Multiple Suzuki–Miyaura Cross‐Coupling Reactions

Abstract

Pentaarylpyridines were conveniently prepared in one step by pentafold Suzuki-Miyaura reactions of pentachloropyridine. Moreover, site selective reactions were performed, leading to various substituted arylpyridines. Pentaarylpyridines were studied in detail by means of DFT calculations and by optical spectroscopy.

Site-selective Suzuki–Miyaura coupling of heteroaryl halides – understanding the trends for pharmaceutically important classes

“…Parent 2,3-, 60b , 75 2,4-, 39 , 75e , 76 and 2,5-dihalopyridines, 60b , 75b , e , 76f , 77 and 2,3,5-trichloropyridine, 78 2,3,5,6-tetrachloropyridine 79 and pentachloropyridine 79 , 80 are known to preferentially undergo SMC reactions at C2/C6. 7 , 12 Whereas 4-aryl-2,3,5,6-tetrachloropyridine can undergo sequential SMC reactions at C2/C6 then C3/C5, 79 3,5-dibromo-2,6-dichloropyridine undergoes sequential SMC reactions at C3/C5 then C2/C6. 81 3,4-Dichloropyridine preferentially undergoes SMC at C4.…”

Chemoselective Synthesis of Arylpyridines through Suzuki–Miyaura Cross‐Coupling Reactions

“…With substrate 3 in hand, we optimized the reaction conditions for the synthesis of monoarylpyridines 4 (Table ). As the C–I bond in postion 2 of starting material should be highly active, we started our optimization with the cheap and easily available Pd(PPh 3 ) 4 as catalyst and chose K 3 PO 4 as base and toluene as solvent based on our previous experiences with the arylation of pyridines . After some experimentation, we found that the best yield of 4a (78 %) was obtained when the reaction was carried out with Pd(PPh 3 ) 4 (5 mol‐%) as the catalyst in a solvent mixture of toluene, water and ethanol (Entry 3).…”

A convenient route to symmetrically and unsymmetrically substituted 3,5-diaryl-2,4,6-trimethylpyridines via Suzuki–Miyaura cross-coupling reaction

“…Such approach was widely applied by many research teams in the construction of polyarylated benzenes [ 56 ], pyridines [ 57 – 60 ], thiophenes [ 61 – 62 ], quinoxalines [ 63 ], pyrazoles [ 64 ] pyrroles [ 65 ], pyrimidines [ 66 – 67 ], benzofuranes [ 68 ], imidazo[1,2- a ]pyridines [ 69 ], diaryl/heteroaryl methanes [ 70 ], and indoles [ 71 ], bearing differently substituted arene rings. An elegant approach to variously arylated pentaarylpyridines was recently proposed by Reimann et al [ 60 ]. The final outcome of such a procedure is governed by many factors, including differences in site reactivity of polyhaloarenes (concerning both regio- and chemoselectivity), reaction conditions (the nature of the palladium/ligand, temperature, base, solvents) and the steric interactions between both cross-coupling partners.…”