Synthesis of new optically active acridino-18-crown-6 ligands and studies of their potentiometric selectivity toward the enantiomers of protonated 1-phenylethylamine and metal ions

Starting from commercially available and relatively inexpensive chemicals, new enantiopure diisobutyl- and dioctyl-substituted acridino-18-crown-6 ether-type ligands [(R,R)-3] and [(R,R)-4], respectively were prepared. The two lipophilic isobutyl [(R,R)-3] and octyl [(R,R)-4] groups on the stereogenic centers of these macrocycles made it possible to use them as potentiometric sensor molecules when incorporated into plasticized PVC membrane electrodes. Ligand (R,R)-3 showed appreciable enantioselectivity toward the enantiomers of 1-phenylethylammonium chloride while macrocycle (R,R)-4 exhibited a high selectivity toward the silver ion.

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(7R,17R)-7,17-Bis(2-methylpropyl)-6,9,12,15,18-pentaoxa-25-azatetracyclo[21.3.1.05,26.019,24]heptacosa-1(26),2,4,19,21,23(27),24-heptaeneC29H39NO5Ee >97%[α]D27=-35.5 (c 0.52, CH2Cl2)Source of chirality: (S)-(+)-leucineAbsolute configuration: (7R,17R)

(8R,16R)-8,16-Dioctyl-6,9,12,15,18-pentaoxa-25-azatetracyclo[21.3.1.05,26.019,24]heptacosa-1(26),2,4,19,21,23(27),24-heptaeneC37H55NO5Ee >97%[α]D20=+1.2 (c 0.58, CH2Cl2)Source of chirality: (R)-(+)-2-hydroxydecanoic acidAbsolute configuration: (8R,16R)

(2R,2′R)-2,2′-Oxybis[(ethane-2,1-diyloxy)decane-2,1-diyl] bis(4-methylbenzenesulfonate)C38H62O9S2Ee >97%[α]36518=+15.7 (c 1.12, CHCl3)Source of chirality: (R)-(+)-2-hydroxydecanoic acidAbsolute configuration: (2R,2′R)

(8R,16R)-8,16-Dioctyl-6,9,12,15,18-pentaoxa-25-azatetracyclo[21.3.1.05,26.019,24]heptacosa-1(26),2,4,19,21,23-hexaene-27-oneC37H55NO6Ee >97%[α]D23=-28.9 (c 1.0, CHCl3)Source of chirality: (R)-(+)-2-hydroxydecanoic acidAbsolute configuration: (8R,16R)