trans-Fused crown ethers from 2,5-O-methylene-D-mannitol: synthesis, X-ray diffraction structure and full nuclear magnetic resonance spectroscopic data of 1,6-diazido-1,6-dideoxy-2,5-O-methylene-3,4-O-naphthalene-2,3-diylbis(oxyethyleneoxyethylene)-D-mannitol and 3,4-di-O-acetyl-1,6-diazido-1,6-dideoxy-2,5-O-methylene-D-mannitol

The crystalline compound 5, named in the title and prepared from technical D-mannitol in 6 steps, has been fully investigated by different spectroscopic methods including MS, IR, 1H, 13C, 14N and 15N NMR. These results confirm the perfect C2-symmetry in solution and provide the complete map of this chiral homotopic crown ether. X-Ray diffraction analysis of compound 5 reveals it exists in a distorted chair conformation as one monocyclic precursor 14. Treatment of compound 5 with acetylene derivatives gave the macrocycles 6 and 7 with bulky symmetric triazole substituents. The anomalous lack of complexing abilities of compounds 5, 6, and most related macrocycles towards phenylglycine methyl ester perchlorates could be explained by the rigidity of the dioxepane framework around the C-3/C-4 axis of D-mannitol.