Qi-Lin Wang

A Copper-Catalyzed Friedel–Crafts Alkylation/Cyclization Sequence: an Approach to Functionalized Pyrrolo[1,2-a]indole Spirooxindoles and 9H-Pyrrolo[1,2-a]indoles

An efficient Cu(OTf)2-catalyzed Friedel-Crafts alkylation/cyclizaiton sequence of 3-substituted indoles with isatin-derived oxodienes was developed, and a series of structurally complex and diverse pyrrolo[1,2-a]indole spirooxindoles were first obtained in up to 99% yields. This protocol proved to be quite general and was also robust for the synthesis of 9H-pyrrolo[1,2-a]indoles.

Diastereoselective Construction of Indole-Bridged Chroman Spirooxindoles through a TfOH-Catalyzed Michael Addition-Inspired Cascade Reaction

The first highly diastereoselective Michael addition/condensation/Friedel-Crafts alkylation cascade reaction of 3-indolyl-substituted oxindoles with ortho-hydroxychalcones was established, which afforded a wide range of polycyclic indole-bridged chroman spirooxindoles with novel and complex scaffolds in moderate to excellent yields.

Diastereoselective construction of 4-indole substituted chromans bearing a ketal motif through a three-component Friedel–Crafts alkylation/ketalization sequence

The first TfOH-catalyzed three-component Friedel–Crafts alkylation/ketalization sequence of indoles, alcohols and ortho-hydroxychalcones was developed to afford a wide range of 4-indole substituted chromans bearing a ketal motif in 77–99% yields. Notably, only a simple filtration was needed to purify them. By altering methanol to CHCl3, 2,4-bisindole substituted chroman with the same indole substituent at the C2 and C4 positions was afforded. Moreover, 2,4-bisindole substituted chromans with different indole substituents could be obtained by treatment of 4-indole monosubstituted chromans with another indole molecule.

An Unexpected FeCl3-Catalyzed Cascade Reaction of Indoles and o-Hydroxychalcones for the Assembly of Chromane-Bridged Polycyclic Indoles

An unexpected FeCl3-catalyzed cascade reaction of simple indoles and o-hydroxychalcone was reported, leading to densely functionalized and strained chromane-bridged polycyclic indoles in moderate to good yields. This reaction not only establishes a new transformation of indoles and o-hydroxychalcones but also provides an efficient method for the synthesis of structurally complex and congested chromane-bridged polycyclic indoles.