Synthesis of Novel Substituted Sulfonyl-Imino-Amidine (or Imidate) UsingN-Sulfonylketenimine under Ultrasound Irradiation

discussion: Our initial studies began with the idea of synthesizing N, N', 3-triphenyl-2-((phenylsulfonyl)imino) propanimidamide 6a using a CuAAC/ N-sulfonylketenimine 3 with phenylisocyanide 4a and aniline 5a under ultrasonic irradiation at 60 W for 50 min. To test our hypothesis, a range of Cu(I) salts and solvents (THF, DMF, MeCN, and DMSO) were employed to 6a. Initially, various solvents were screened using CuI as a catalyst (Table 1, entries 1-4). To further improve the yield, different copper salts such as CuBr and Cu2O were screened in the presence of Et3N as base (Table 1, entries 5-12). The reaction proceeded smoothly in all the cases to give the desired 6a in comparable yield. Also, to confirm the necessity of copper salts for the reaction, we have investigated the synthesis of compound 6a under different conditions in the presence of copper metal and without adding any catalyst. The results in Table 1 show that no product was observed under these conditions. To investigate the role of the catalyst amount, we have investigated the reaction of a sample of the derivatives (compound 6a) under optimal conditions with 5 mol% of copper iodide catalyst. Evidence shows that by reducing the amount of catalyst from 10 mol% to 5 mol%, the reaction time changed to 2 hours under ultrasonic conditions.