Tautomers　are　widespread　in　organic　chemistry,　and　their　unique　reactivity　allows　diverse　transformations.　In　this　work,　the　incorporation　of　nearby　amide　ring-fusion　site　offered　a　versatile　platform　for　controlling　dual　reactivity　based　dynamic　covalent　chemistry　(DCC)　of　aldehyde　ring-chain　tautomers.　A　suite　of　2-formylbenzosulfonamide　derived　tautomers　were　prepared,　and　the　intramolecular　ring-chain　equilibrium　and　intermolecular　dynamic　covalent　reactions　along　the　underlying　mechanistic　foundation　were　investigated.　By　regulating　the　substituent　electronic　effect　and　solvent　effect,　ring-chain　tautomerization　equilibrium　was　readily　regulated　in　solution.　The　adjacent　amide　NH　participates　in　intramolecular　hydrogen　bonding,　as　revealed　by　crystal　analysis.　Furthermore,　the　addition　of　acid　and　the　change　of　solvent　allowed　turning　on/off　the　intramolecular　cyclization　from　the　amide　group　to　create　fused　ring　scaffolds.　Finally,　the　reversible　covalent　reactions　with　amine　nucleophile　reagents　maintained　the　intermolecular　reactivity　successfully.　The　molecular　and　pathway　diversity　reported　herein　sets　the　scene　for　future　design　and　applications.　©　2024　Elsevier　Ltd