A Phenyl‐Ethynyl‐Macrocycle: A Model Compound for “Geländer” Oligomers Comprising Reactive Conjugated Banisters

Macrocycle 1 is assembled as smallest member of a series of Gelander oligomers with a conjugated banister comprising exclusively sp(2)- and sp-hybridized carbon atoms. The synthesis of 1 is based on an acetylene scaffolding approach, comprising Sonogashira cross-coupling reactions in combination with protection group strategies and a final cyclization based on an oxidative acetylene coupling using Eglinton-Breslow reaction conditions. Macrocycle 1 serves as model compound for the investigation of the structural integrity of the strained 1,3-diyne subunit. An enhanced reactivity of the strained 1,3-diyne subunit is documented by its engagement in Huisgen's (2+3) cycloaddition when exposed to an azide at elevated temperature. Both structures, macrocycle 1 and cycloaddition-product 2, are fully characterized including their solid-state structure obtained by X-ray diffraction analysis.