MOLECULAR TWEEZERS FROM CYCLOPHANE BUILDI NG-BLOCKS

Molecular tweezer compounds 1-6 with convergent carboxyl groups are pr epared from suitable functionalized [2.2]- and dithia[3.3]metacyclopha ne building blocks by using several multistep strategies. The C-C coup ling of two cyclophanes according to the Hagihara method leads to alky ne-spacered double cyclophanes. These new preorganized, acyclic host c ompounds of the cyclophane-type react as molecular tweezers and can se lectively ''grasp'' guest molecules and bind them strongly. X-ray anal yses underline the syn conformations of the dithia[3.3]- and the anti conformation of the [2.2]metacyclophanes.