Inherently Chiral Molecular Clips: Synthesis, Chiroptical Properties, and Application to Chiral Discrimination

• Published in: Chemistry : a European journal Vol. 13; no. 9; pp. 2473 - 2479
• Main Authors: Fukuhara, Gaku, Madenci, Süreyya, Polkowska, Jolanta, Bastkowski, Frank, Klärner, Frank-Gerrit, Origane, Yumi, Kaneda, Masayuki, Mori, Tadashi, Wada, Takehiko, Inoue, Yoshihisa
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.01.2007; WILEY‐VCH Verlag; Wiley
• Subjects: Chemistry; Chemistry, Multidisciplinary; chirality; circular dichroism; exciton coupling; host-guest systems; molecular clips; Physical Sciences; Science & Technology; RECOGNITION THERMODYNAMICS; CONVERGENT FUNCTIONAL-GROUPS; host-guest systems; chirality; N-ALKYLPYRIDINIUM SALTS; CRYSTAL-STRUCTURE; circular dichroism; SUPRAMOLECULAR STRUCTURES; SELECTIVE COMPLEXATION; exciton coupling; TWEEZERS; BINDING-PROPERTIES; GUEST COMPLEX; RECEPTORS; molecular clips
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200601585

Inherently chiral molecular clips (MCs), pseudoenantiomeric anti‐1 and anti‐2, as well as mesoid syn‐3, were synthesized by diastereodifferentiating repetitive Diels–Alder reactions of the achiral bisdienophile 6 with chiral diene 5 generated in situ from (−)‐menthyl 3,4‐bis(dibromomethyl)benzoate 4. These MCs were successfully separated by chiral HPLC to give optically active anti‐1 and anti‐2 and almost optically inactive syn‐3. The structures of anti‐1, anti‐2, and syn‐3 were assigned by high‐resolution NMR and the absolute configurations of anti‐1 and anti‐2 were determined by the exciton‐chirality method. Optically active anti‐2 can serve as a chiral host. It binds the HCl adduct of D‐tryptophan methyl ester (D‐TrpOMe⋅HCl) 3.5 times stronger than the L‐enantiomer (KD/KL=3.5). Clipped together: An inherently chiral molecular clip, possessing a new chiral skeleton, forms a more stable host–guest complex with D‐tryptophane methyl ester (see graphic) than with the corresponding L enantiomer.