Double Click for Chirality: Chiral Dibenzo-cycloocta-bis-triazoles via Strain-Promoted Alkyne-Azide Cycloaddition

Abstract

The synthetically convenient strain promoted double azide cycloaddition of the Sondheimer-Wong diyne produces resolvable chiral dibenzo-cycloocta-bis-triazoles whose stereogenicity, to date, has gone unrecognised. Enantiomers were separable by chiral HPLC and showed no racemization at 100 °C. This unique method to produce chiral substrates was exploited for the synthesis and resolution of a chiral fluorescent BF2-azadipyrromethene, with absorption and emission spanning the important spectral range of 600 to 700 nm. The fluorophore properties were studied utilising X-ray structural analysis, electronic circular dichroism spectra and DFT calculations.