-Proline N-oxide dihydrazides as an efficient ligand for cross-coupling reactions of aryl iodides and bromides with amines and phenols

Flexible Approach for the Synthesis of Annulated 4H-Pyrans Based on a Cu(I)-Catalyzed C-Allylation/O-Vinylation Reaction of Cyclic 1-Bromoallyl Tosylates with Cyclic and Acyclic 1,3-Dicarbonyls

The Cu(I)-catalyzed reaction between five-, six-, seven-, and eight-membered cyclic 1-bromoallyl tosylates and five- and six-membered cyclic 1,3-dicarbonyls in DMF at 80 °C using Cs₂CO₃ as a base and 2-picolinic acid as an additive selectively delivers a wide array of bisannulated 4H-pyrans in a single step with yields up to 92%. The transformations are considered to proceed as intermolecular C-allylations/intramolecular O-vinylations. With six-membered cyclic 1-bromoallyl tosylates and acyclic β-ketoesters as substrates, the corresponding 5,6,7,8-tetrahydro-4H-chromene-3-carboxylates are obtained with yields up to 59%.

Mild Copper-Catalyzed, l-Proline-Promoted Cross-Coupling of Methyl 3-Amino-1-benzothiophene-2-carboxylate

Cu-catalyzed N-arylation is a useful tool for the chemical modification of aromatic heterocycles. Herein, an efficient carbon–nitrogen cross-coupling of methyl 3-amino-1-benzothiophene-2-carboxylate with a range of (hetero)aryl iodides using CuI, l-proline and Cs₂CO₃ in dioxane at moderate temperature is described. The procedure is an extremely general, relatively cheap, and experimentally simple way to afford the N-substituted products in moderate to high yields. The structures of the new heterocyclic compounds were confirmed by NMR spectroscopy and HRMS investigation.

Recent Progress Concerning the N-Arylation of Indoles

This review summarizes the current state-of-the-art procedures in terms of the preparation of N-arylindoles. After a short introduction, the transition-metal-free procedures available for the N-arylation of indoles are briefly discussed. Then, the nickel-catalyzed and palladium-catalyzed N-arylation of indoles are both discussed. In the next section, copper-catalyzed procedures for the N-arylation of indoles are described. The final section focuses on recent findings in the field of biologically active N-arylindoles.