Assembly of trifluoromethylated fused tricyclic pyrazoles via cyclization of β-amino cyclic ketones.

Fused polycyclic pyrazoles are an important class of heterocyclic compounds; thus, the development of efficient methods for their preparation becomes highly urgent. Herein, we reported an efficient method for the synthesis of trifluoromethylated fused tricyclic pyrazoles via intramolecular cyclization of cyclic ketone-derived amines. Mechanistic studies provide evidence for the in situ generation of trifluoromethylated β-diazo ketones as intermediates via diazotization with the use of tert-butyl nitrite. The synthetic utility of this method is highlighted by scale-up synthesis and the derivatization of the obtained fused tricyclic pyrazole products.