Abstract
Preliminary studies related to the design and development of new cycloalkyne reagents for metal-free click coupling are reported. Cyclononynes are more stable than cyclooctynes, and the robust benzocyclononyne platform offers spontaneous reactivity toward azides at rates competitive with other azidophiles that have been employed for metal-free click coupling. Benzocyclononynes (e.g., 1) provide valuable insight into the design of new cycloalkynes for strain-promoted azide–alkyne cycloaddition (SPAAC) couplings for applications in which side reactions and decomposition of the reagent must be kept to a minimum.
Supporting Information
X-ray files in CIF format, ORTEP plots, plots of kinetic data, and copies of NMR spectra. This material is available free of charge via the Internet at http://pubs.acs.org. The supplementary crystallographic data for compounds 3 and 12 have also been deposisted with the Cambridge Crystallographic Data Centre (CCDC 847775 and 847776, respectively). These data can be obtained free of charge via the Internet at http://www.ccdc.cam.ac.uk/cgi-bin/catreq.cgi.
