A Facile Route to<i>Ortho</i>-Hydroxyanilnes through an Ir<sup>III</sup>-Catalyzed Direct C−H Amidation of 2-Phenoxypyridines
作者:Lianhui Wang、Zi Yang、Mengqi Yang、Miaodou Tian、Changsheng Kuai、Xiuling Cui
DOI:10.1002/asia.201701028
日期:2017.10.5
A highly efficient and regioselective IrIII‐catalyzed C−H amidation of 2‐phenoxypyridines has been developed by using sulfonyl azides as an amino source. The amidated products were provided in good‐to‐excellent yields with broad functional‐group tolerance. Furthermore, the 2‐pyridyl moiety in the amidated products could be readily removed, thus offering an efficient route to synthetically useful ortho‐hydroxyanilnes
An efficient palladium‐catalyzed decarboxylative ortho‐acylation of 2‐aryloxypyridines with α‐oxocarboxylicacids is described. In this new transformation, the aromatic C(sp2)H bond was successfully acylated to give diverse aromatic ketones regioselectively in moderate to good yields. The pyridine group can be removed easily after the acylation to give the corresponding 2‐hydroxy aromatic ketones
Palladium(II)-Catalyzed <i>Ortho</i> Arylation of 2-Phenoxypyridines with Potassium Aryltrifluoroborates via C−H Functionalization
作者:Jean-Ho Chu、Pi-Shan Lin、Ming-Jung Wu
DOI:10.1021/om100494p
日期:2010.9.27
An efficient synthesis of ortho-arylated 2-phenoxypyridines catalyzed by palladium acetate is described. Treatment of 2-phenoxypyridines with two and a half equivalents of potassium aryltrifluoroborate and 10 mol % of Pd(OAc)(2) in the presence of two equivalents of Ag(2)CO(3), one equivalent of p-benzoquinone (BQ), and four equivalents of DMSO with (or without) H(2)O at 130-140 degrees C for 48 h in dried CH(2)Cl(2) gave the ortho-arylated 2-phenoxypyridines in modest to excellent yields. p-Benzoquinone is found to be an important ligand and co-oxidant for the transmetalation reductive elimination step in the catalytic reaction. The investigation of kinetic isotope effect (k(H)/k(D)) is determined to be 5.25, which indicates that C H bond cleavage occurs in the rate-determining step. One of the arylated compounds, 2-(4'-nitrobiphenyl-2-yloxy)pyridine, was treated with methyl trifluoromethanesulfonate and subsequently sodium methoxide to give the 2-(4-nitrophenyl)phenol in 79% yield, demonstrating that pyridine is a removable directing group.