The Preparation of Crown Ethers Containing Dicinnamoyl Groups and Their Complexing Abilities

The reaction of 1, 10-bis[p-[2-(chloroformyl)vinyl]phenyl]-1,4,7,10-tetraoxadecane with the dipotassium salt of catechol in the presence of a catalytic amount of 18-crown-6 in benzene gave 5,6-benzo-4,7,17,20,23,29-hexaoxa[10.10]paracyclopha-1,5,9-triene-3,8-dione (10a) in 3.6% yield. Also, 24,25-benzo-1,4,7,10,13,23,26-heptaoxa[13.10]paracyclopha-20,24,28-triene-22,27-dione (10b) and 27,28-benzo-1,4,7,10,13,16,26,29-octaoxa[16.10]paracyclopha-23,27,31-triene-25,30-dione (10c) were obtained by the same method in 3.1 and 3.0% yields, respectively. Irradiation of the acetonitrile solutions of the crown ethers, 10a, 10b and 10c, by Pyrex-filtered UV light (>300 nm) gave the corresponding intramolecular [2+2]photocycloadducts, 11a, 11b and 11c, in 95.8, 93.2 and 90.1% yields, respectively. The structures of 11a, 11b and 11c were confirmed to be the β-form by their 1H NMR spectra. The photoreversible cleavage of 11a, 11b and 11c by 220 nm UV light gave the corresponding starting crown ethers, 10a, 10b and 10c, in 30, 40 and 61% yields, together with their geometrical isomers in 30, 50 and 27% yields, respectively. Compound 10c showed selective extraction abilities for K+ and Rb+ cations compared with 11c.