Control of Guest Inclusion and Chiral Recognition Ability of 6‐ O ‐Modified β‐Cyclodextrins in Organic Solvents by Aromatic Substituents at the 2‐ O Position

The host‐guest chemistry and applications of cyclodextrins in aqueous media is well established. However, a comprehensive study in organic solvents is lacking. Here, we report the design and synthesis of 6‐ O ‐ tert ‐butyldimethylsilylated β‐cyclodextrin (TBDMS‐β‐CD) bearing various aromatic substitutions at the 2‐ O position and their inclusion complex formation with aromatic guests in nonpolar organic solvents. Compared to the parent TBDMS‐β‐CD, these derivatives exhibit at least a 10‐fold increase in inclusion ability toward pyrene through cooperative guest binding with the CD cavity and the aromatic substituents at the 2‐ O position. The type of the aromatic substituent largely affects the chiral recognition ability of TBDMS‐β‐CD toward 1‐(1‐naphthyl)ethylamine in cyclohexane. A TBDMS‐β‐CD derivative with a p ‐tolyl substituent has a remarkable chiral selectivity for the ( S )‐1‐(1‐naphthyl)ethylamine over the corresponding ( R )‐isomer ( K S /K R =4.1±0.5), whereas a TBDMS‐β‐CD derivative with a 2‐picolyl substituent shows the inverse chiral selectivity ( K R /K S =8.7±0.6).