Modular Access to Tetrasubstituted Imidazolium Salts through Acid-Catalyzed Addition of Isocyanides to Propargylamines

摘要: Propargylamines, prepared through A3-coupling of primary amines, aldehydes and terminal alkynes, react with isocyanides in an HCl-catalyzed process to yield tetrasubstituted imidazolium salts. The key step the mechanism involves generation amidine intermediate, from isocyanide insertion into N–H bond propargylamine, which situ evolves by cyclization upon alkyne moiety. scope is analyzed only shows restrictions for aliphatic whereas it quite general regarding aldehyde, inputs. protocol allows preparation a wide array adducts, tandem one-pot processes being also feasible. Mechanistic studies using selected substrates have been used determine profile reaction some substitution functional group limitations. Some post-synthetic transformations salts performed as well.