Weinreb Amide as Secondary Station for the Dibenzo‐24‐crown‐8 in a Molecular Shuttle

Abstract

Here is reported the synthesis of a new molecular shuttle: it consists of a dibenzo‐24‐crown‐8 (DB24C8) that surrounds a molecular axle containing an ammonium group and a newly considered Weinreb amide as stations. At the protonated state the DB24C8 is localized around the best ammonium station, while deprotonation‐carbamoylation of the ammonium triggers the shuttling of the macrocycle around the Weinreb amide site. Further post‐interlocking modification of the [2]rotaxane was attempted through the cleavage of the Weinreb amide bond using a Grignard reagent. While the non‐interlocked molecular axle was cleaved after a short time in mild conditions, the Weinreb amide bond remained unaltered in the [2]rotaxane species over time, even in the presence of a larger amount of Grignard and at a higher temperature, highlighting the protection shield of the macrocycle around the encircled axle.