BF3‑Promoted Divergent Reactions between Tryptophols and Propargylic Alcohols

Trifluoroboron-promoted cascade reactions between tryptophols and propagylic alcohols furnished three types of skeletons, including carbazoles, cyclopenta­[b]­furo­[2,3-b]­indoles, and allenyl furo­[2,3-b]­indoles, with excellent selectivity based on the substrate structure. Tryptophols without a substituent on the 2-position of the indole ring reacted with 1,1,3-triphenylprop-2-yn-1-ol and 9-(phenylethynyl)-9H-fluoren-9-ol to give carbazoles and cyclopenta­[b]­furo­[2,3-b]­indoles, respectively, while the reaction of 2-substituted tryptophols afforded allenylfuro­[2,3-b]­indoles.

三氟化硼（Trifluoroboron）介导的色醇与炔丙醇之间的级联反应，可基于底物结构差异以优异的选择性生成三类骨架结构，分别为咔唑、环戊并[b]呋喃并[2,3-b]吲哚以及联烯基呋喃并[2,3-b]吲哚。当吲哚环2位无取代的色醇分别与1,1,3-三苯基丙-2-炔-1-醇、9-(苯乙炔基)-9H-芴-9-醇反应时，可得到咔唑与环戊并[b]呋喃并[2,3-b]吲哚；而2位取代的色醇参与反应时，则生成联烯基呋喃并[2,3-b]吲哚。