Convenient synthesis of selected meta- and ortho-substituted pentaarylpyridines via the Suzuki-Miyaura cross-coupling reaction

Arylpyridines: A Review from Selective Synthesis to Atropisomerism

“…Interestingly, only three compounds 193, 194, and 195 were found in the reaction mixture in the ratio 3:2:1 (Scheme 58). 133 Compounds 194 and 195 turned out to be stable atropisomers even at elevated temperatures (180 °C). 133…”

“…133 Compounds 194 and 195 turned out to be stable atropisomers even at elevated temperatures (180 °C). 133…”

“…35,[125][126][127] Synthesis of multiply arylated pyridines is not an easy task, but many effective syntheses of fully arylated pyridine derivatives have been reported. 124,[128][129][130][131][132][133] Particularly important are the controlled (regio-and chemoselective) synthesis of pentaarylpyridines. [129][130][131][132] Also in 2017, the first synthesis of a sterically demanding orthosubstituted pentaarylpyridine was reported.…”

“…[129][130][131][132] Also in 2017, the first synthesis of a sterically demanding orthosubstituted pentaarylpyridine was reported. 133 An interesting example of the use of [4+2]cycloaddition in a key step for the synthesis of multiply arylated pyridines is the methodology proposed by Yamaguchi and co-workers in 2017. 128 In this strategy for the synthesis of 2,3,6-triaryl-5-hydroxypyridines 162, 2,4-diaryl-5-chlorooxazole 161 was a key intermediate (Scheme 42).…”

“…However, in 2017 a multi-gram procedure for the preparation of 191 was reported that opened the way for such difficult arylations. 133 It has been shown that pyridine 191 may be quantitatively pentaarylated with different metaand para-substituted arylboronic acids. Moreover, the reaction is possible also for 2-tolylboronic acid with the use of Pd(OAc) 2 in the presence of K 3 PO 4 in toluene.…”