Fujita Kahee

pH-Controlled Supramolecular Enantiodifferentiating Photocyclodimerization of 2-Anthracenecarboxylate with Capped γ-Cyclodextrins

γ-Cyclodextrins capped with p-cresolbisbenzimidazole at the primary rim were synthesized and used as chiral hosts for mediating the enantiodifferentiating [4 + 4] photocyclodimerization of 2-anthracenecarboxylate. The use of 6A,6E-capped γ-cyclodextrin led to the formation of the anti-head-to-head photodimer in –5% enantiomeric excesses (ee) at pH 11 but in 28% ee at pH 6 with accompanying switching of product chirality, for which a pH-responsive conformational change of the capping moiety is likely to be responsible.

Selective preparation of hexakis(6-O-arenesulfonyl)-α-cyclodextrin

Abstract Hexakis(6- O -tosyl)-α-cyclodextrin and hexakis(6- O -(2-naphthalenesulfonyl))-α-cyclodextrin were prepared selectively through the reaction of α-cyclodextrin by use of bis(tributylstannyl) oxide and the corresponding sulfonyl chloride in 32.4 and 77.9%, respectively.