Taming Tethered Nitreniums for Alkene Functionalization Reactions

Here, we present the first examples of amino-trifluoroacetoxylations of alkenes using N-alkoxy carbamate tethers. The trifluoroacetate group can be conveniently removed from the product by treatment with a solution of NH3 in MeOH. Hypervalent iodine oxidants mediate this transformation, providing a “green” alternative to existing intramolecular aminohydroxylation protocols which use toxic metals such as osmium. In all cases examined, the reaction is regioselective and stereospecific, with the geometry of the starting alkene controlling the diastereomeric outcome. By analogy to prior art and from our own observations, we posit that a transient nitrenium species serves as a key intermediate in this transformation.