Synthesis of C-2-symmetrical [1,1 '-binaphthalene]-2,2 '-diamines with additional chelating groups attached to the nitrogen atoms as potential ligands for asymmetric catalysis

Reductive amination of 2-hydroxybenzaldehyde, using a combination of NaBH4 and (R)-[1,1'-binaphthalene]-2,2'-diamine, served as the key step in the sy nthesis of the potentially tetradentate ligands (R)-N,N'-bis(2-hydroxybenzy l) [1,1'-binaphthalene]-2,2'-diamine and (R)-N,N'-bis(2-hydroxybenzyl)-N,N' -dimethyl[1,1'-binaphthalene]-2,2'-diamine. In anal -ogy, amination of 2-br omobenzaldehyde with (R)-[1,1'-binaphthalene]-2,2'-diamine produced (R)-N:N '-bis(2-bromobenzyl)[1,1'-binaphthalene]-2-2'diamine, whose conversion into the novel diphosphine ligand (R)-N,N'-bis [2-(diphenylphosphino)benzyl] -N ,N'-dimethyl[1,1'-binaphthalene]-2,2'-diamine was readily attained in two s teps. CD spectra of the new binaphthyl derivatives are presented.