New Methods of Resolution and Enrichment of Enantiomeric Excesses of 1,1'-Bi-2-naphthol.

Partial resolution of racemic 1,1'-bi-2-naphthol (1) was readily achieved to obtain enriched (scalemic) 1 using (S)-proline (2). The structure of the complex 3 formed between 1 (2 equiv) and (S)-proline (1 equiv) was characterized by an X-ray diffraction method. Enantiomeric excesses of the incompletely resolved 1 were enriched to obtain essentially pure (R)- and (S)-1 following a simple procedure using B(OH)(3) and TMEDA.