4-Halogeno-sydnones for fast strain promoted cycloaddition with bicyclo-[6.1.0]-nonyne

Abstract

New sydnone derivatives have been synthesized and screened for their capacity to undergo fast copper-free cycloaddition reaction with bicyclo-[6.1.0]-nonyne. The influences of substitution in positions N-3 and C-4 of sydnones have been particularly studied leading to the identification of highly reactive partners for bio-orthogonal ligation reactions.