Resolution of (RS)-Binol through co-crystal formation with 3-n-propyl-4-((R/S)-1′-phenylethylamino)butanoic acid

Abstract

A method for the optical resolution of (RS)-Binol to obtain optically pure (S)-Binol (99% ee) through co-crystal formation with (RS)-3-n-propyl-4-((S)- 1′-phenylethylamino)butanoic acid (3RS, 1′S) and similarly optically pure (R)-Binol (99% ee) through co-crystal formation with (RS)-3-n-propyl-4- ((R)-1′-phenylethylamino)butanoic acid (3RS,1′R), in high yield is reported. The individual co-crystal of optically pure (S)-3-n-propyl-4-((S)- 1′-phenylethylamino)butanoic acid (3S,1′S) (99% ee) with (S)-Binol, and (R)-3-n-propyl-4-((S)-1′-phenylethylamino)butanoic acid (3R,1′S) (90% ee) with (S)-Binol have been analyzed by single crystal X-ray diffraction to understand hydrogen bonding in the crystal structure and the chiral recognition parameters.