Iridium-catalyzed acid-assisted asymmetric hydrogenation of oximes to hydroxylamines

Hydrogenations that tolerate N–O bonds Catalysts that add hydrogen to carbon-carbon, carbon-nitrogen, and carbon-oxygen double bonds are among the most widely used in synthetic chemistry. They are particularly adept at delivering just one of two mirror-image products. However, they may also target adjacent bonds in the compound that would be better left intact. Mas-Roselló et al. report that an iridium catalyst paired with a strong acid can hydrogenate C=N bonds without disturbing a weak N–O bond on the same nitrogen center. The reactions proceed at room temperature with high enantioselectivity. Science , this issue p. 1098