Copper-catalyzed C-N Bond Cleavage: Synthesis of N-sulfonylformamidines from N-(2-pyridinylmethyl)benzenesulfonamides.

Unlabelled: A broad range of N-sulfonyformamidines, widely used intermediates for drugs, were synthesized in moderate to excellent yields from 2-Pyridinemethanamine as N-source via Coppercatalyzed C-N cleavage. Firstly, N-(2-pyridinylmethyl)benzenesulfonamides were smoothly synthesized via 2-pyridinemethanamine and sulfonyl chlorides, then reacted with N,Ndimethylformamide dimethyl acetal to obtain the corresponding N-Sulfonylformamidines analogs, during which pyridin-2-ylmethyl and sulfonyl groups were essential for the C-N bond cleavage. The current work presents a valuable complementarity to the synthesis of N-sulfonyformamidines as 2- pyridinemethanamine can provide the N source and sulfonyl chloride,s which could be original materials.

Background: N-sulfonylamidines have gained considerable attention from schools and industries because of their unique bioactivity. Since Pinner's strategy, expanding the synthesis methods of Nsulfonylamidines has been the goal of many organic chemists over the past decades. Besides the crash reaction conditions and the participation of undesirable reagents, the production of Nsulfonylamidines commonly required unstable ammonia and azides as the source of nitrogen that hindered the further development and application of N-sulfonylamidine derivatives.

Objective: The study aims to find a stable N source to replace NaN or NH to synthesize N-sulfonylamidines from sulfonyl chlorides.

Methods: Firstly, N-(2-pyridinylmethyl)benzenesulfonamides were smoothly synthesized via 2- pyridinemethanamine and sulfonyl chlorides. Then the reaction conditions of N-(2-pyridinylmethyl) benzenesulfonamides and N,N-dimethylformamide dimethyl acetal (DMF-DMA) were screened and optimized. The reaction was processed in glycol at 80 degree centigrade for 8 hours with the addition of 5 mol% Cu(OAc)·HO as a catalyst.

Results: Taking advantage of pyridin-2-ylmethyl, a scope of N-Sulfonylformamidines were synthesized from those N-(2-pyridinylmethyl)benzenesulfonamides under copper-catalyzed C-N bond cleavage.

Conclusion: This ready synthetic method will be more of a promising inspiration for bioactive compound synthesis and drug development than for an innovative approach to synthesizing N-sulfonylformamidines.