New reactivity patterns in activated indoles with 2-methyl substituents

The synthesis and reactive properties of two new 3-aryl-2-methyl-4,6-dimethoxyindoles are reported. These compounds show typical electrophilic substitution and addition reactions at C7, but not oxidative dimerisation because of the reactivity of the 2-methyl group. This methyl group can be effectively oxidised to a carbaldehyde by selenium dioxide, but formation of 7,7′-diindolylselenides also occurs.