Department of Chemistry, University of Minnesota Twin Cities, Minneapolis, Minnesota 55455, United States.
J Am Chem Soc. 2021 Apr 14;143(14):5308-5313. doi: 10.1021/jacs.1c01354. Epub 2021 Apr 2.
The triazole heterocycle has been widely adopted as an isostere for the amide bond. Many native amides are α-chiral, being derived from amino acids. This makes α--chiral triazoles attractive building blocks. This report describes the first enantioselective triazole synthesis that proceeds via nickel-catalyzed alkyne-azide cycloaddition (NiAAC). This dynamic kinetic resolution is enabled by a spontaneous [3,3]-sigmatropic rearrangement of the allylic azide. The 1,4,5-trisubstituted triazole products, derived from internal alkynes, are complementary to those commonly obtained by the related CuAAC reaction. Initial mechanistic experiments indicate that the NiAAC reaction proceeds through a monometallic Ni complex, which is distinct from the CuAAC manifold.
三氮唑杂环已被广泛用作酰胺键的等排体。许多天然酰胺是α-手性的，它们是由氨基酸衍生而来的。这使得α-手性三氮唑成为有吸引力的构建块。本报告描述了首例通过镍催化的炔烃-叠氮环加成（NiAAC）进行的对映选择性三氮唑合成。这种动态动力学拆分是通过烯丙基叠氮化物的自发[3,3]-σ重排来实现的。由内炔烃衍生的 1,4,5-三取代三唑产物与通过相关的 CuAAC 反应通常获得的产物互补。初步的机理实验表明，NiAAC 反应通过单金属 Ni 配合物进行，这与 CuAAC 途径不同。
