Chiral enrichment of 2-amino-2'-hydroxy-1,1'-binaphthyl

Article abstract of DOI:10.1016/S0957-4166(98)00203-1

A new synthetic procedure for the formation of 2-amino-2'-hydroxy-1,1'- binaphthyl, and a new purification procedure through the formation of Schiff bases, purification of the Schiff bases, and breakdown of the Schiff bases through amine exchange, are described. Through the new purification procedure, greater than 99% purity of the compound can be obtained easily and reliably. A set of procedures were examined to compare the efficiency and reliability to resolve 2-amino-2'-hydroxy-1,1'-binaphthyl into enantiomers. A new procedure was discovered to enrich enantiomeric excess from less than 10% to 95-99% in one step. Even a racemic mixture from an achiral procedure can be enriched to 67% e.e. in about 4% yield. The X-ray crystal structure of the racemic mixture [rhombohedral, space group Iba2, a=15.718(2) A, b=21.703(2) A, c=8.5398(9) A, V=2913.2(5) A³, RI=0.0705, Z=8, d(calcd)=1.301 g/cm³, F(000)=1200 e] was solved to elucidate the intriguing behavior of this compound.