Kinetics studies of rapid strain-promoted [3 + 2]-cycloadditions of nitrones with biaryl-aza-cyclooctynone
Strain-promoted cycloadditions of cyclic nitrones with biaryl-aza- cyclooctynone (BARAC) proceed with rate constants up to 47.3 M-1 s-1, this corresponds to a 47-fold rate enhancement relative to reaction of BARAC with benzyl azide and a 14-fold enhancement over previously reported strain promoted alkyne-nitrone cycloadditions (SPANC). Studies of the SPANC reaction using the linear free energy relationship defined by the Hammett equation demonstrated that the cycloaddition reaction has a rho value of 0.25 ± 0.04, indicating that reaction is not sensitive to substituents and thus should have broad applicability. The Royal Society of Chemistry 2012.
McKay, Craig S.,Chigrinova, Mariya,Blake, Jessie A.,Pezacki, John Paul