Preparation and NMR spectra of four isomeric diformyl[2.2]paracyclophanes (cyclophanes 66)

Abstract

Four isomeric dialdehydes 4, readily available from cycloaddition of propiolic aldehyde (2) to 1,2,4,5-hexatetraene (1), were separated by chromatography and recrystallization, and were characterized by their spectroscopic data. The individual isomers can now be easily identified from their 1H NMR spectra even if only one of them is present.