Axially chiral binaphthyl surrogates with an inner N-H-N hydrogen bond.

Novel chiral binaphtyl surrogates with an inner hydrogen bond have been created. The NH appears at 13.0-13.3 ppm in thier (1)H NMR spectrum, indicating extremely strong hydrogen bonding. Enantiomers of these compounds were stable at ambient temperature and separable by HPLC with a chiral stationary phase. The half-lives of racemization of the enantiomer are in the range 3 months to 2 years at 20 degrees C, and the barriers for racemization are in the range 27.0 to 28.2 kcal/mol. An X-ray crystal analysis of the compound (R = CHPh(2)) shows that the pseudonaphthyl skeleton including CN...HN is almost completely planar and the dihedral angle between the pseudonaphthalene and naphthalene rings is 128 degrees .