Metal-Free Coupling of Azoles with 2- and 3-Haloindoles Providing Access to Novel 2- or 3-(Azol-1-yl)indole Derivatives

Thermal or microwave-mediated heating of 2- or 3-haloindoles with azoles (pK(a) < 8) provides a straightforward, metal-free, and environmentally friendly access to novel 2-(azol-1-yl)indoles. Furthermore, previously unknown 2,3-bis(azolyl-1-yl)indoles can be prepared from 2,3-dihaloindoles by sequential reaction with two distinct azoles. This operationally simple acid-catalyzed process delivers novel indole derivatives in fair to excellent yields and expands the chemical diversity of substitutions that can be introduced on this medicinally important scaffold.