A Synthetic Approach to N-Aryl Carbamates via Copper-Catalyzed Chan–Lam Coupling at Room Temperature

Abstract

A mild and efficient synthesis of N-arylcarbamates was achieved by reacting azidoformates with boronic acids in the presence of 10 mol % of copper chloride catalyst. The reaction proceeds readily in an open flask at room temperature without additional base, ligand, or additive. Rapid access to urea analogues via a two-step one-pot procedure is enabled by reacting N-arylcarbamates with aluminum-amine complexes. In addition, among several boronic acid derivatives prepared, dimethylphenyl boronate was found to react rapidly in its reaction with benzyl azidoformate, invoking in situ generation of this species in the catalytic cycle.

Chan–Lam coupling reaction of sulfamoyl azides with arylboronic acids for synthesis of unsymmetrical N-arylsulfamides

“…The possible mechanism for the Chan-Lam coupling between sulfamoyl azides and arylboronic acids is presented below (Scheme 5). 7,13 At rst, the sulfamoyl azides coordinate with the Cu(I) salt A that provides copper nitrene and are transformed to Cu(II) complex B. 14 Subsequently, the aryl boronic acid is in equilibrium with the methyl boronate ester, 15…”

“…Recently, an improved approach for the synthesis of N-arylsulfonamides and N-arylcarbamates using sulfonyl azides and azidoformates respectively at room temperature in the presence of a copper catalyst and boronic acids has been successfully reported by our group (Scheme 2). 6,7 We thus envisioned an alternative synthetic method in order to contribute to the existing unsymmetrical N-arylsulfamides synthesis. Unlike previous synthetic methods, we expected our process would proceed rapidly at room temperature in high yields without the use of any additives and would not require relatively expensive palladium catalyst (Scheme 1, route D).…”

Ausgewählte Kupfer‐katalysierte Reaktionen für die Bildung von C‐N‐, C‐O‐, C‐S‐ und C‐C‐Bindungen

“…Die Reaktion ist ohne Zugabe von Base, Ligand oder Additiv nach 2 h abgeschlossen. Später wurde dieses Verfahren auf die Synthese von N‐Arylcarbamaten aus Azidoformiaten und Boronsäuren verwendet . Kieanmehr und Mitarbeiter beschrieben ein effizientes Katalysatorsystem für die Arylierung von Cyanationen mit Arylboronsäuren in einem alkoholischen Lösungsmittel (Nr.…”

Chan‐Evans‐Lam C−N Coupling Promoted by a Dinuclear Positively Charged Cu(II) Complex. Catalytic Performance and Some Evidence for the Mechanism of CEL Reaction Obviating Cu(III)/Cu(I) Catalytic Cycle

“…Air is routinely used for the reaction as an oxidant. The CEL coupling later was elaborated to allow C−N, C−O, C−S, C−Se, C−P bond formation via copper(II)‐catalyzed pathways of arylboronic acids with a wide range of nucleophiles, including sensitive substrates, which is critically important in numerous commercial chemical processes . There are several reports for three‐component, tandem CEL‐type reactions and heterocycles synthesis .…”