1,1′-Bis(diphenylphosphino)ferrocene]dichloropalladium/1,1′-Bis(diphenylphosphino)ferrocene Catalyzed Synthesis of 2,3-Diamino-1,4-naphthoquinones

Abstract

A general method for the synthesis of 2,3-diamino-1,4-naphthoquinone derivatives via the palladium-catalyzed coupling of 2-amino-3-chloro-1,4-naphthoquinones with amines is described. The scope and limitations of the coupling process using [1,1 '-bis(diphenylphosphino)ferrocene] dichloropalladium [PdCl 2 (dppf)], combined with 1,1'-bis(diphenylphosphino)ferrocene (dppf) as a ligand and sodium tert-butoxide as base were investigated, and found to catalyze efficiently the coupling of 2-(arylamino)-3-chloro- 1,4-naphthoquinones with primary aryl- and alkylamines. A series of novel 2,3-diamino-1,4-naphthoquinone derivatives previously unavailable were obtained by application of this procedure.