An Improved Synthesis of Disubstituted 2H-indazoles using Microwaves

Microwaves have been used to produce a practical, high-yielding, and scalable synthesis method for producing disubstituted 2H-indazoles. With this technique, a large class of 2H-indazoles can be effectively produced from substituted 2-bromobenzaldehyde, aromatic amine and NaN3 using [Cu(phen)(PPh3)2]NO3 as catalysts. With outstanding purity and yields, the current one-pot synthetic sequence enables the addition of two structural diversity points to broaden the chemical space.