Domino alkyne insertion/aldol reaction/aromatization of 2-alkynyl indole-3-carbaldehyde with 1,3-diketones: entry to 2-indolyl phenols

A novel one-pot base-promoted insertion of indolyl 2-alkynes into a C-C single bond of 1,3-diketones, followed by intramolecular aldol reaction and dehydrative aromatization is described. This reaction cascade leads to the construction of 2-indolyl phenols involving the formation of the C1-C2 and C3-C4 bonds of phenols resulting from the formal insertion process with a good substrate scope. Further, these bifunctional compounds were used in a novel arylative annulation in the presence of Grignard reagents to provide chromeno-indole frameworks.

Automated summary

A novel one-pot base-promoted insertion reaction of indolyl 2-alkynes into a C-C single bond of 1,3-diketones, followed by intramolecular aldol reaction and dehydrative aromatization, has been described. This reaction cascade allows for the construction of 2-indolyl phenols, involving the formation of both C1-C2 and C3-C4 bonds of phenols with a good substrate range. Furthermore, these bifunctional compounds can be used in a novel arylative annulation in the presence of Grignard reagents to provide chromeno-indole frameworks.