Tandem Cycloaddition of Azides to 3,3-Diaminoacrylonitriles (2-Cyanoacetamidines) and Cornforth-Type Rearrangement as an Approach to 5-Amino-1,2,3-triazole-4-N-substituted Imidamides

An efficient base-catalyzed, metal-free method for thesynthesisof 5-amino-1,2,3-triazole-4-N-sulfonyl- and arylimidamides,directed by the structure of the amidine group, has been developed.It is based on a previously unknown tandem process involving cycloadditionreaction to 3,3-diaminoacrylonitriles (2-cyanoacetamidines) with aryl(alkyl)sulfonylor aryl azides and Cornforth-type rearrangement. During the reactionoptimization, different factors were found to facilitate the titlereaction, which include the use of a strong base and N-mono- or N,N & PRIME;-disubstituted3,3-diaminoacrylonitriles. The reaction is tolerant to variously N-monosubstituted and N,N & PRIME;-disubstituted 3,3-diaminoacrylonitriles and to various aryl-and aryl/alkyl sulfonyl azides. The developed method has a broad scopeand can be applied to obtain a variety of 5-amino-1,2,3-triazole-4-carbimidamidesbearing at the N-1 position alkyl, allyl, propargyl, benzyl,cycloalkyl, and heteroaryl substituents and sulfonyl and aryl substituentsat the amidine group. Post-cyclization reactions of prepared 5-amino-1,2,3-triazoleswith DMF-DMA DMA-DMF leads to 1,2,3-triazolo[4,5-d]pyrimidines, 8-aza purine analogues demonstrating the applicabilityof the prepared compounds in organic synthesis.