Regioselective Copper(I)-Catalyzed Direct C(3)-H (Hetero)arylation of 6-(Hetero)arylated 1,2,4-Triazolo[4,3-]pyridazines: Ligand-Free Approach.

The first efficient Cu(I) catalyzed regioselective C3-(hetero)arylation of 6-(hetero)arylated 1,2,4-triazolo[4,3-]pyridazines has been developed to streamline the synthesis of pharmaceutically important 3,6-diarylated 1,2,4-triazolo[4,3-]pyridazines. This direct (hetero)arylation is compatible with a range of aryl iodides and tolerates a variety of functional groups (23 examples). A series of new 3,6-diarylated 1,2,4-triazolo[4,3-]pyridazines were synthesized with good to excellent yields (up to 98%).

Simple and Expedient Access to Novel Fluorinated Thiazolo- and Oxazolo[3,2-]pyrimidin-7-one Derivatives and Their Functionalization via Palladium-Catalyzed Reactions.

An efficient, versatile, and one-pot method for the preparation of novel fluorinated thiazolo- and oxazolo[3,2-]pyrimidin-7-ones is described from 2-aminothiazoles or 2-amino-oxazoles and fluorinated alkynoates. This transformation, performed under transition-metal-free conditions, offers new fluorinated cyclized products with good to excellent yields. Moreover, the functionalization of these -fused scaffolds via the Suzuki-Miyaura and Sonogashira cross-coupling reactions led to the synthesis of highly diverse thiazolo- and oxazolo[3,2-]pyrimidin-7-ones.