1,6-Dideoxy-D-mannitol-based 20-crown-6 ethers: synthesis and influence of the substituents upon complexing properties toward phenylglycinium methyl esters

Ten novel homotopic 20-crown-6-ethers have been prepared from 1,3∶4,6-di-O-benzylidene-D-mannitol. Substituents could be introduced on the alditol framework after the macrocyclisation in order to modify their complexing abilities. In one case, a low but significant enantiomeric excess (32% ee) in favour of L(S)-phenylglycine methyl ester could be ascertained when two bulky vic-triazole substituents were associated into the vicinity of the cavity. The formation of an adjacent trans-fused ring on C-3/C-4 of the mannitol framework mediated the complexing abilities of these macrocycles toward 2-phenylglycine methyl ester perchlorates.