Preparation and Properties of Chiral Spiroborate Esters with an O₃BN Framework

Asymmetric Reduction of Oxime Ethers Promoted by Chiral Spiroborate Esters with an O3BN Framework

“…Chiral inductors ( R , S )- 1 and ( S , S )- 1 can be conveniently prepared from racemic 1,1‘-bi-2-naphthol, boric acid, and ( S )- proline via diastereomeric separation 8 or alternatively synthesized from enantiopure ( R )- or ( S )-1,1‘-bi-2-naphthol, boric acid, and ( S )-proline via a one-pot reaction (Scheme ) . However, ( R )-proline analogues of ( R , S )- 1 and ( S , S )- 1 were not synthesized due to the greater expense of ( R )-proline.…”