Catalytic asymmetric (3 + 3) cycloaddition between different 2-indolylmethanols

The catalytic asymmetric (3 + 3) cycloaddition between different 2-indolylmethanols has been established, in which a series of chiral indole-fused six-membered heterocycles were constructed in high yields with excellent enantioselectivities. This work not only has established the first catalytic asymmetric cycloaddition between different 2-indolylmethanols but also provided a powerful strategy for constructing enantioenriched indole-fused six-membered rings. Additionally, biological evaluation discovered some products with promising antitumor activities. Notably, theoretical calculations performed on the reaction pathway and activation mode provide an in-depth understanding of this catalytic asymmetric (3 + 3) cycloaddition among different 2-indolylmethanols, which will advance the understanding of the chemistry of indolylmethanols.