Copper-catalyzed three-component annulation toward pyrroles the cleavage of two C-C bonds in 1,3-dicarbonyls.

The first copper-catalyzed three-component annulation of α,β-unsaturated ketoximes, 1,3-dicarbonyls and paraformaldehyde has been documented. This novel strategy achieved the two C-C bond cleavage of 1,3-dicarbonyl compounds directly as a single-carbon synthon and provided a new and highly efficient method for the synthesis of 2,3-disubstituted pyrroles in moderate to good yields with broad functional group compatibility.

Copper-catalyzed [4+2] oxidative annulation of α,β-unsaturated ketoxime acetates with ethyl trifluoropyruvate.

A novel route for tandem C-N/C-O formation copper-catalyzed [4+2] oxidative annulation of α,β-unsaturated ketoxime acetates with ethyl trifluoropyruvate to synthesize valuable trifluoromethyl-containing 2-1,3-oxazines in moderate to good yields is developed. This procedure represents the first [4+2] oxidative annulation of oxime derivatives with activated CO bonds and provides an alternative route towards functionalized 2-1,3-oxazines.

Copper-Catalyzed Three-Component Cascade Annulation for Divergent Syntheses of Imidazoles and Dihydroimidazoles.

The first example of divergent -heterocycle syntheses through a copper-catalyzed three-component reaction of ,-unsaturated ketoximes, paraformaldehyde, and amines has been documented. In particular, this divergent synthetic strategy was achieved by controlling the reaction conditions to afford the corresponding imidazoles and dihydroimidazoles in moderate to good yields with a broad substrate scope and good functional group compatibility.

The copper-catalyzed synthesis of dihydrooxazoles from α,β-unsaturated ketoximes and activated ketones.

The first copper-catalyzed [3+2]-type condensation reaction of α,β-unsaturated ketoximes with activated ketones has been described for the synthesis of dihydrooxazoles, especially trifluoromethyl-decorated dihydrooxazoles. Notable features of this method include its broad substrate scope, good functional group tolerance, and simple operation.

Copper-catalyzed regioselective [3+2] annulation of malonate-tethered acyl oximes with isatins.

A copper-catalyzed regioselective [3+2] annulation of malonate-tethered acyl oximes with isatins was developed, affording valuable 2,3-dihydrooxazole-spirooxindoles in moderate to good yields with excellent diastereoselectivity. The reaction sequence involves Cu(i) initiated N-O bond cleavage, 1,5-HAT and C-N bond formation. The protocol features mild reaction conditions and broad substrate scope.

NHI-Triggered [4 + 2] Annulation of α,β-Unsaturated Ketoxime Acetates with -Acetyl Enamides for the Synthesis of Pyridines.

The NHI-triggered formal [4 + 2] annulation of α,β-unsaturated ketoxime acetates with -acetyl enamides has been developed. The current protocol employs electron-rich enamides as C2 synthons and enables the efficient and straightforward construction of polysubstituted pyridines in moderate to good yields based on metal-free systems. The reaction tolerates a wide range of functional groups and represents an alternate route toward the synthesis of pyridine derivatives.

Copper-Catalyzed N-O Cleavage of α,β-Unsaturated Ketoxime Acetates toward Structurally Diverse Pyridines.

The copper-catalyzed [4 + 2] annulation of α,β-unsaturated ketoxime acetates with 1,3-dicarbonyl compounds for the synthesis of three classes of structurally diverse pyridines has been developed. This method employs 1,3-dicarbonyl compounds as C2 synthons and enables the synthesis of multifunctionalized pyridines with diverse electron-withdrawing groups in moderate to good yields. The mechanistic investigation suggests that the reactions proceed through an ionic pathway.