Mechanistic Study of In Situ Generation and Use of Methanesulfonyl Azide as a Diazo Transfer Reagent with Real-Time Monitoring by FlowNMR

The mechanistic pathway by which the hazardous diazo transfer reagent methanesulfonyl azide can be formed in situ, from methanesulfonyl chloride and aqueous sodium azide, has been investigated using real-time reaction monitoring by FlowNMR. In the presence of triethylamine, rapid generation of methanesufonyl azide is observed, via a mechanistic pathway consistent with involvement of a sulfene or methanesulfonyl triethylammonium intermediate. Accordingly, it is possible to generate and use methanesulfonyl azide in a single synthetic step for a diazo transfer process.