Phthalocrowns: Isoindoline–Crown Ether Macrocycles

Abstract

The reaction of diiminoisoindoline with amine-terminated polyethers results in the formation of phthalocrown macrocycles. For <i>n</i> = 1 (where <i>n</i> is the number of ether units), a 2 + 2 condensation takes place, but for <i>n</i> = 2 and 3, a 1 + 1 macrocycle formation occurs. The <i>n</i> = 2 phthalocrown is particularly stable due to a strong intramolecular hydrogen bond, but the <i>n</i> = 3 ring hydrolyzes to form a 3-imino-1-oxoisoindoline derivatized crown ether species. For the <i>n</i> = 1 phthalocrown, we observed dynamic behavior in the ¹H NMR spectrum, and using VTNMR were able to measure a Δ<i>G</i>^⧧ = 44.6 kJ/mol for proton exchange