Switched enantioselectivity by solvent components and temperature in photocyclodimerization of 2-anthracenecarboxylate with 6~A,6~X-diguanidio-γ-cyclodextrins

摘要

A series of 6~A,6~X-diguanidio-γ-cyclodextrins(CDs) were used as chiral hosts for mediating the enantiodifferentiating [4 + 4] photocyclodimerization of 2-anthracenecarboxylic acid(AC). These y-CD derivatives form stable 1:2 ternary complexes with AC in aqueous ammonia solutions and the head-tohead photodimers 3 and 4 were greatly enhanced in the presence of these diguanidio-γ-CDs. The enantioselectivity of chiral photodimers 2 and 3 is a critical function of the temperature and the ammonia contents, showing inverted product chirality by changing these external factors.