Densely functionalized polyether macrocycles can be prepared in one pot in yields up to 60% by the rhodium(II)-catalyzed decomposition of methyl diazoacetoacetate in the presence of a variety of substituted or unsaturated 5- and 6-membered ring cyclic ethers. A comprehensive analysis of the solid state conformations of the macrocyclic geometries is detailed as well as novel mechanistic insights about the multi-component condensation reaction.