page_title: 1,1'-Bi-2-naphthol
section_title: BINOL derivatives
hierarchical_section_title: 1,1'-Bi-2-naphthol / BINOL derivatives
caption_attribution_description: English: structure of a chiral phosphoric acid derived from BINOL
context_page_description: 1,1′-Bi-2-naphthol is an organic compound that is often used as a ligand for transition-metal catalysed asymmetric synthesis. BINOL has axial chirality and the two enantiomers can be readily separated and are stable toward racemisation. The specific rotation of the two enantiomers is ±35.5°. BINOL is a precursor for another chiral ligand called BINAP. The volumetric mass density of the two enantiomers is 0.62 gcm⁻³.
context_section_description: Aside from the starting materials derived directly from the chiral pool, (R)- and (S)-BINOL in high enantiopurity (>99% ee) are two of the most inexpensive sources of chirality for organic synthesis, costing less than $0.6/g when purchased in bulk from chemical suppliers.  As a consequence, it serves as an important starting material for other sources of chirality for stereoselective synthesis, both stoichiometric and substoichiometric (catalytic).
  Many important chiral ligands are constructed from the binaphthyl scaffold and ultimately derived from BINOL as a starting material, BINAP being one of the most well known and important.
  The compound aluminium lithium bis(binaphthoxide) (ALB) is prepared by reaction of BINOL with lithium aluminium hydride.  In a different stoichiometric ratio (1:1 BINOL/LiAlH₄ instead of 2:1), the chiral reducing agent BINAL (lithium dihydrido(binaphthoxy)aluminate) is produced.
  It has been employed in an asymmetric Michael reaction with cyclohexenone and dimethyl malonate:
caption: Structure of a chiral phosphoric acid derived from BINOL.[7]
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