NEW SYMMETRICAL CHIRAL DIBENZYL-SUBSTITUTED AND DIPHENYL-SUBSTITUTED DIAMIDO-18-CROWN-6, DITHIONOAMIDO-18-CROWN-6, DIAZA-18-CROWN-6, AND AZAPYRIDINO-18-CROWN-6 LIGANDS
Huszthy, P; Oue, M; Bradshaw, JS; Zhu, CY; Wang, TM; Dalley, NK; Curtis, JC; Izatt, RM
Eleven new chiral macrocycles (1-11, see Figure 1) of the pyridino-18-crown-6 type have been prepared. Nine diazapyridino-crown ligands contain two amide (1, R = benzyl; 4, R = phenyl), two N-methylamide (7, R = phenyl), two thionoamide (2, R = benzyl; 5, R = phenyl), two N-methylthionoamide (8, R = phenyl), two amine (3, R = benzyl; 6, R = phenyl), or two N-methylamine (9, R = phenyl) groups incorporated into the macroring. The appropriate chiral diamine was treated with dimethyl 2,6-pyridinedicarboxylate (or 2,6-pyridinedicarbonyl dichloride), O,Ó-dimethyl 2,6-pyridinedicarbothioate, or 2,6-pyridinedimethyl ditosylate to prepare these materials. The macrocyclic diamides were also converted to the macrocyclic dithionoamides using Lawesson's reagent and the latter macrocycles were reduced to the diamines. A new symmetrically substituted dimethylazapyridino-18-crown-6 ligand (10) and its N-acetyl derivative 11 were also prepared. The interactions of some of the new chiral ligands with (R)- and (S)-[α-(1-naphthyl)ethyl]ammonium perchlorate were studied by 1H NMR spectral techniques. The degree of enantiomeric recognition was determined by the difference of the free energy of activation values (ΔΔG*) and the difference in log K values for these interactions. The X-ray analyses of the dithionoamido ligands (2,5, and 8) showed severe deviations of the S and N atoms from the plane of the pyridine ring, especially in the case of 8. The optical rotation of 8 changed with time due to conformational changes. The relevant conformations of 8 are discussed in light of the X-ray crystallography, molecular mechanics, and 1H NMR spectra. © 1992, American Chemical Society. All rights reserved.
