Synthesis of Rigid Macrocyclic Phenols and Their Catalytic Applications in Diels-Alder Reactions

Macrocyclic catalysts having a phenol-acetylene-phenol triad were developed as a hydrogen-bond donor catalyst. The rigid macrocyclic framework suppressed intramolecular hydrogen bonds between neighboring phenolic hydroxy groups. The preorganized phenol-acetylene-phenol moiety formed efficient intermolecular hydrogen bonds with carbonyl groups of substrates. The hydrogen-bond donor catalysts accelerated the Diels-Alder reaction of methyl vinyl ketone with cyclopentadiene. The catalytic ability was higher than that of an acyclic counterpart.