Palladium-Catalyzed Tandem Allylation of o-Phenylenediamines Using 2-Butene-1,4-diol Directly

The direct activation of C−O bonds in 2-butene-1,4-diol by palladium complexes has been accelerated by carrying out the reactions in the presence of a titanium reagent. Palladium-catalyzed tandem allylation of o -phenylenediamines with 2-butene-1,4-diol leads to 1,2,3,4-tetrahydro-2-vinylquinoxalines. The cyclization of o -phenylenediamine with 2-butene-1,4-diol catalyzed by palladium acetate coordinated with ( R )-BINAP as the chiral ligand leads to optically active 1,2,3,4-tetrahydro-2-vinylquinoxaline ( 3a ) with 19% ee and in 58% yield.