Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Meilong Road No. 130, Shanghai, 200237, China.
Org Lett. 2011 Jun 17;13(12):3068-71. doi: 10.1021/ol200940a. Epub 2011 May 16.
In this paper, a reagent-controlled [3+2] annulation of γ-functionalized butynoates 1 and 1C,3O-bisnucleophiles 2 is reported, which leads to three distinct furan skeletons 3-5. A PPh(3) catalyst preferentially attached the β-position of 1a, facilitating α-addition to furnish Type I annulations. With the assistance of Ag(2)O, Type II annulations were achieved via selective γ-substitution. In the absence of the PPh(3) catalyst, the reagent Cs(2)CO(3) promoted β-addition to realize Type III annulations.
本文报道了一种试剂控制的γ-官能化丁炔酸酯 1 和 1C,3O-双亲核试剂 2 的[3+2]环加成反应，生成了三个不同的呋喃骨架 3-5。PPh(3)催化剂优先与 1a 的β位结合，有利于α加成，生成 I 型环加成产物。在 Ag(2)O 的协助下，通过选择性γ取代实现了 II 型环加成。在没有 PPh(3)催化剂的情况下，试剂 Cs(2)CO(3)促进β加成，实现了 III 型环加成。
