New Routes to Racemic and Enantiomerically Pure (S)-BINOL Diesters

A. COSTANTINO; R. OCAMPO; M.G. MONTIEL SCHNEIDER; G.FERNANDEZ; S. MANDOLESI; L. KOLL

SYNTHETIC COMMUNICATIONS

TAYLOR & FRANCIS INC

Lugar: Londres; Año: 2013 vol. 43 p. 3192 - 3202

0039-7911

Since 1990, the enantiomeric atropoisomers of 1,1´-binaphthyl-2,2´-diol (BINOL, I) have become one of the most widely used ligands for both stoichiometric and catalytic asymmetric reactions.[1] The preparation of racemic BINOL and its resolution has been widely studied, and some well-established methods are reported.[2] Stereoselectivity control is based in the utilization of molecules from the Cn or Dn groups of symmetry that allow the prediction of enantioselectivity due to the existence of only one reactive species. Under this supposition, chiral atropoisomers become very interesting, especially those corresponding to binaphtyl systems. The potential of I as a ligand for metal-mediated catalysis was first recognized in 1979 by Noyori in the reduction of aromatic ketones and aldehydes.[1g] BINOL itself, however, does not always give satisfactory results in asymmetric catalysis, and since Noyori?s discovery there has been an ongoing interest in modified BINOL ligands. The rigid structure, thermal stability and the C2 symmetry of the chiral binaphthyl molecules play an important rol in assymetric induction. In the last few years, BINOL derivatives have become attractive molecules with applications in chiral supramolecular recognition, crystal engineering, electro optical materials and polymers, among others.[3-6] These type of binaphtyl compounds are often synthetized using enantiomerically pure BINOL as the starting material easily transforming the 2,2´-hydroxy groups into other functional groups.[7]