Facile preparation of [4.4]metacyclophane- and [5.5]paracyclophane-type macrocycles from arylboronic acids and salicylideneaminoaryl alcohols.

Four different salicylideneaminoaryl alcohols have been treated with arylboronic acids in order to prepare air-stable cyclophane-type macrocyclic systems. In two cases, this objective could be realized with the high-yield formation of [4.4]metacyclophane and [5.5]paracyclophane derivatives. The skeleton in these macrocycles is held together by two chiral boron atoms. In the other two cases, monomeric boronates or polymeric material were obtained. The title structures were characterized by spectroscopic techniques and X-ray crystallography. They show transannular C-H...O hydrogen bonding, but no intramolecular pi-pi interactions. A synthetic strategy for the preparation of further boron macrocycles is presented.