Axial [6,6′-(2,4-pentadioxy)]-1,1′-biphenyl-2,2′-diamine (PD-BIPHAM): practical synthesis and applications in asymmetric hydrogenation

A rapid, reliable, and atom-economical procedure for the novel axially biphenyl diamine, (R,R,Sax)-PD-BIPHAM 1, has been developed successfully by using highly efficient central-to-axial transformation strategy. The attractive feature of this methodology is that no tedious resolution was needed. The effectiveness of this new chiral skeleton was initially demonstrated by highly enantioselective hydrogenation of α-dehydroamino acid esters.