Copper and In Situ-Generated Triflic Acid Relay-Promoted Four-Component Cascade Reaction for the Construction of Polysubstituted Cycloguanidines

Abstract

An unprecedented copper and in situ-generated triflic acid relay-promoted four-component cascade reaction of cyanamides, diaryliodonium triflates, propargylic amines, and H2O was established for rapid and concise construction of diverse five-membered cycloguanidines. Copper-catalyzed guanidination/intramolecular hydroamination and in situ-generated HOTf-accelerated hydration proceeded sequentially with high level of chemoselectivity and regioselectivity, and six new bonds were simultaneously built in high yields. Thus, diaryliodonium triflates served not only as an arylation reagent but also as an internal acid promoter, establishing an alternative strategy for highly efficient utilization of diaryliodonium trifates.

Copper-Catalyzed, Ligand-Controlled N(sp3)- or N(sp)-Selective Arylation of Cyanamides

“…Finally, the N­(sp)-selective arylation of cyanamides 1 has only been reported in the presence of an external nucleophile, such as a primary or a secondary amine, thus leading to guanidines 4 (Scheme B) . This transformation can be metal-free with diaryliodonium triflates as arylation reagents, or copper-catalyzed, as exemplified in Scheme B, using arylboronic acids . Indeed, in the presence of copper­(II) chloride (10 mol %), bipyridine (10 mol %), potassium carbonate, and oxygen in toluene at 100 °C, guanidines 4 were obtained in good to excellent yields.…”