A practical protocol for the construction of hydroxylated 2-(1-phenyl-1H-benzo[d]imidazol-2-yl)phenols (PBIs) from N-phenyl-o-phenylenediamine with benzaldehydes was developed. The cascade reaction was enabled by heating a mixture of the two substrates in the presence of air as an oxidant and anhydrous Cu(OAc)₂ as a catalyst in dimethyl sulfoxide, and a diverse series of PBIs were synthesized in moderate to good yields (69–81%). Furthermore, the synthesis of the PBIs was enabled via a one-pot cascade reaction that proceeded through subsequent dehydration condensation, intramolecular cyclization, and aromatic C–H hydroxylation. This protocol can be used for the synthesis of hydroxylated PBI via a one-pot annulation C–H hydroxylation reaction rather than through a series of multistep reactions, which provides the possibility of further modification.

中文翻译：

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Cu(II) 催化 N-苯基-邻苯二胺与苯甲醛的级联：一步直接构建 2-(1-苯基-1H-苯并[d]咪唑-2-基)苯酚

开发了一种从N-苯基-邻苯二胺与苯甲醛构建羟基化 2-(1-苯基-1H-苯并[ d ]咪唑-2-基)苯酚 (PBI)的实用方案。_{通过在空气作为氧化剂和无水 Cu(OAc) 2}存在下加热两种底物的混合物来实现级联反应作为二甲基亚砜的催化剂，合成了多种系列的 PBI，收率中等至良好（69-81%）。此外，PBI的合成是通过一锅级联反应实现的，该反应通过随后的脱水缩合、分子内环化和芳香族C-H羟基化进行。该方案可用于通过一锅环化C-H羟基化反应而不是通过一系列多步反应来合成羟基化PBI，这提供了进一步修饰的可能性。