Dynamic Figure Eight Chirality: Multifarious Inversions of a Helical Preference Induced by Complexation

• Published in: Journal of organic chemistry Vol. 80; no. 15; pp. 7613 - 7625
• Main Authors: Katoono, Ryo, Tanaka, Yuki, Kusaka, Keiichi, Fujiwara, Kenshu, Suzuki, Takanori
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 07.08.2015; Amer Chemical Soc
• Subjects: binding sites; Chemistry; Chemistry, Organic; hydrogen bonding; optical isomerism; organic chemistry; organic compounds; Physical Sciences; Science & Technology; EXPLOSIVE DECOMPOSITION; INTRAMOLECULAR INTERACTIONS; ABSOLUTE-CONFIGURATION; CRYSTAL-STRUCTURE; POINT CHIRALITY; LIQUID-CRYSTALS; CHIROPTICAL PROPERTIES; MOLECULAR SWITCH; VERSATILE SYNTHETIC ROUTE; COBALT(II) COMPLEX
• ISSN: 0022-3263; 1520-6904; 1520-6904
• DOI: 10.1021/acs.joc.5b01206

We demonstrate two types of inversion of a helical preference upon the 1:1 complexation of a dynamic figure eight molecule with a guest molecule through the controlled transmission of point chirality. We designed a series of macrocycles that prefer a nonplanar conformation with figure eight chirality. These macrocycles are composed of a chirality-transferring unit (terephthalamide) and a structure-modifying unit (two o-phenylene rings spaced with a varying number of triple bonds). The former unit provides a binding site for capturing a guest molecule through the formation of hydrogen bonds. The attachment of chiral auxiliaries to the former unit induces a helical preference for a particular sense through the intramolecular transmission of point chirality. For relatively small-sized macrocycles, the preferred sense was reversed upon complexation with an achiral guest. Contrary preferences before and after complexation were both seen for chiral auxiliaries associated with a figure eight host through two-way intramolecular transmission of the single chiral source. Alternatively, the helical preference induced in relatively large-sized macrocycles was reversed only when a figure eight host formed a 1:1 complex with a particular enantiomeric guest through the supramolecular transmission of point chirality in the guest. This stereospecific inversion of a helical preference is rare.