Orchestrated Triple C-H Activation Reactions Using Two Directing Groups: Rapid Assembly of Complex Pyrazoles

摘要

A sequential triple CH activation reaction directed by a pyrazole and an amide group leads to the well-controlled construction of sterically congested dihydrobenzo[e]indazole derivatives. This cascade reaction demonstrates that the often problematic competing CH activation pathways in the presence of multiple directing groups can be harvested by design to improve step economy in synthesis. Pyrazole as a relatively weak coordinating group is shown to direct Csp3H activation for the first time.