Cobalt-Catalyzed Hydroazidation

The hydrohydrazination represented a general solution for the amination of alkenes, but the protected hydrazines obtained are sometimes difficult to transform to the free amines. At this point, we turned to sulfonyl azides as nitrogen sources, based on then-capacity to react both with enolates and carbon-centered radicals. Mechanistic investigations of the hydrohydrazination reaction had suggested a radical character for the formed organocobalt intermediate. We were pleased to see that the Cobalt-catalyst 4 was able to promote the hydroazidation of 4-phenylbut-l-ene (3) with ethanesulfonyl azide (7), giving the product derived from the formal Markovnikov addition of hydrazoic acid onto the C-C double bond exclusively, albeit in moderate yields (50%). 

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Waser J, Nambu H, Carreira EM (2005) Cobalt-catalyzed hydroazidation of olefins convenient access to alkyl azides. J Am Chem Soc 127(23) 8294-8295 Shyam PK, Jang HY (2014) Metal-organocatalytic tandem azide addition/oxyamination of aldehydes for the enantioselective synthesis of P-amino a-hydtoxy esters. Eur J Org Chem... 

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