1) The new synthetic procedure devised for (1) shows the following features:
2) The possibility of selective deprotection of (1) affords the bis-tosylamido (10) and the bis-benzyl (3) derivatives, which are versatiles building block for the preparation of macropolycyclic receptors, an example of which is (4).
3) Results of the extent of complexation show the great capability of these new receptors in dissolving solid ammonium salts and hydrochlorides of aminoacids methyl esters in organic low polar solvents. Under the same conditions, but using diaza-18-crown-6 (15) as ligand, values of the extent of complexation are, in any case, very low. Indeed it must be stressed that, in all these experiments, was used a solid salt/ligand ratio = 1.
1) Anelli P. L., Montanari F., Quici S., Ciani G., Sironi A., J. Org. Chem., 53, 5292 (1988).
2) Bradshaw J. S., Krakowiak K. E., Izatt R. M. in "Aza-crown Macrocycles" Heterocyclic Compounds, Interscience Publ., J. Wiley, New-York, Vol. 51 (1993).