UNSATURATED CROWN ETHERS: STILBENO-CROWN ETHERS
Stilbenocrown ethers 3a,c and 4a,b were synthesized in a cyclization reaction of benzoin with oligoethylene glycol ditosylates(2a-c) under a phase-transfer condition. Extractions of aqueous alkali picrates(Na+–Cs+) were examined with the distilbenocrown ethers 4a,b, the partially-hydrogenated tetraphenylcrown ethers 6a,b and the fully-hydrogenated tetracyclohexylcrown ethers 7a,b.