Synthesis and properties of a trapezoid shaped macrocycle with different [n]yne units

Abstract

A new alkyne-based macrocycle that combines monoyne, diyne and tetrayne is reported. Despite its unusual trapezoid shape, the bending of the tetrayne unit allows the macrocycle to be unstrained. The macrocycle is synthesized by a combination of selective deprotection of silylated alkyne, Castro–Stephen–Sonogashira coupling and copper-mediated oxidative homocoupling. The final intramolecular cyclization proceeded in surprisingly high yield (72%) using modified Eglinton conditions in moderate dilution.