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

Takeo Kawabata; Changsheng Jiang; Kazuhiro Hayashi; Kazunori Tsubaki; Tomoyuki Yoshimura; Swapan Majumdar; Takahiro Sasamori; Norihiro Tokitoh

doi:10.1021/ja808213r

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

J Am Chem Soc. 2009 Jan 14;131(1):54-5. doi: 10.1021/ja808213r.

Authors

Takeo Kawabata¹, Changsheng Jiang, Kazuhiro Hayashi, Kazunori Tsubaki, Tomoyuki Yoshimura, Swapan Majumdar, Takahiro Sasamori, Norihiro Tokitoh

Affiliation

¹ Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.

PMID: 19093814
DOI: 10.1021/ja808213r

Abstract

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 .