Potassium Persulfate-Promoted N -Nitrosation of Secondary and Tertiary Amines with Nitromethane under Mild Conditions

Modified NAP test: A simple and Responsive Nitrosating Methodology for Risk Evaluation of NDSRIs

N-Nitroso compounds have been listed as one of the cohorts of concern as per ICH M7. In recent years, the regulatory focus has shifted from common nitrosamines to nitroso-impurities of drug products. Thus, the detection and quantification of unacceptable levels of nitrosamine drug substance-related impurities are of great concern for analytical scientists during drug development. Moreover, risk assessment of nitrosamines is also an essential part of the regulatory filling. For risk assessment, the Nitrosation Assay Procedure suggested by WHO expert group in 1978 is being followed. However, it could not be adopted by the pharmaceutical industries due to the limitation of drug solubility and artefact formation in the test conditions. In this work, we have optimized an alternative nitrosation test to investigate the likelihood of direct nitrosation. The technique is simple, where the drug solubilized in an organic solvent is incubated at 37°C with a nitrosating agent named tertiary butyl nitrite in a 1:10 molar ratio. LC-UV/MS-based chromatographic method was developed to separate drug substances and respective nitrosamine impurities using the C18 analytical column. The methodology was successfully tested on five drugs with varying structural chemistry. The procedure is straightforward, effective, and quick for the nitrosation of secondary amines. This modified nitrosation test and WHO prescribed nitrosation test have been compared and found that the modified methodology is more effective and time-saving.

Catalytic Aerobic N-Nitrosation by Secondary Nitroalkanes in Water: A Tandem Diazotization of Aryl Amines and Azo Coupling

Secondary nitroalkanes underwent oxygen-mediated nitro-nitrite isomerization, serving as versatile N-nitrosating agents under aerobic conditions. To capitalize on the newly discovered aerobic nitro-nitrite isomerization phenomenon, a phase-transfer catalysis system employing KSeCN and TBAI was developed, in which the tandem diazotization and azo coupling with nitroalkanes as well as N-nitrosation of amines were accomplished. The current tandem diazotization and azo coupling strategy provides a facile synthesis of areneazo-2-(2-nitro)propane derivatives, a safe synthetic alternative to aryl diazonium salts.

The recent advances in K2S2O8-mediated cyclization/coupling reactions via an oxidative transformation

Recently the K₂S₂O₈ mediated cyclization/coupling reactions to construct carbon–carbon/carbon–heteroatom bond via oxidative transformation is became much interesting in organic synthesis.

tert-Butyl nitrite promoted transamidation of secondary amides under metal and catalyst free conditions

Transamidation of secondary amides with various amines is demonstrated using tert-butyl nitrite. The reaction proceeds through the N-nitrosamide intermediate and provides the desired products in excellent yields.