Regioselective C6‐Arylation of Thieno[3,2‐c]pyrazole Heterocycles with Aryl Iodides

Regioselective C6‐arylation of thieno[3,2‐ c ]pyrazoles with aryl iodides as coupling partners has been developed. This strategy was performed in the presence of Pd(OAc) 2 as catalyst in combination with AgOTf as an oxidant and TFA in dimethylacetamide. In all experiments, only the C6‐arylated thieno[3,2‐ c ]pyrazole was isolated since its C5‐regioisomer was not observed, indicating the high regioselectivity of this approach. The catalytic system used is compatible with a variety of 3‐functionalized thieno[3,2‐ c ]pyrazoles and iodoaryl electrophiles, providing access to 3,6‐disubstituted thieno[3,2‐ c ]pyrazoles in yields ranging from 49% to 94%.