A concise route for dibenzoazacyclooctynes (DIBACs) synthesis was developed based on Pictet-Spengler reaction and a novel cobalt decomplexation method established for dibenzo-fused cyclooctyne-cobalt complexes. The method allowed for the facile preparation of functionalized DIBACs, including bisDIBAC, which served as an efficient bisreactive linker for protein modification via the double-click reaction.