Nitrogen–carbon bonds are ubiquitous in products ranging from chemical feedstock to pharmaceuticals. As ammonia is among the least expensive bulk chemicals produced in the largest volume, one of the greatest challenges of synthetic chemistry is to develop atomefficient processes for the combination of NH3 with simple organic molecules to create nitrogen–carbon bonds. Transition-metal complexes can readily render a variety of N–H bonds reactive enough to undergo functionalization, including those of primary and secondary amines. However, with a few exceptions,[1, 2] metals react with ammonia to afford supposedly inert Lewis acid–base complexes, as first recognized in the late 19th century by Werner.[3] Consequently, the homogeneous catalytic functionalization of NH3 remained elusive [4] until the recent discovery by Shen and Hartwig [5] and Surry and Buchwald [6] of the palladiumcatalyzed coupling of aryl halides with ammonia in the presence of a stoichiometric amount of a base. An even more appealing process would be the addition of NH3 to carbon–carbon multiple bonds, a process that would occur ideally with 100% atom economy.[7] Although various homogeneous catalysts, including alkali metals,[8] early [9] and late transition metals,[10] and d-[11] and f-block elements,[12] have been used to effect the so-called hydroamination reaction, none of them were reported to be effective when NH3 is used as the amine partner.[13] Herein we report that cationic gold (I) complexes supported by a cyclic (alkyl)(amino) carbene (CAAC)[14] ligand readily catalyze the addition of ammonia to a variety of unactivated alkynes and allenes to provide a diverse array of linear and cyclic nitrogencontaining compounds.

We showed recently that the cationic CAAC–gold complex A was very robust and exhibited unusual catalytic reactivity towards alkynes.[15] This discovery prompted us to investigate whether such a complex could activate alkynes sufficiently to enable the addition of NH3.[16] Thus, excess ammonia was condensed into a sealable NMR tube containing A (5 mol%), 3-hexyne, and deuterated benzene. Upon heating to 160 C for 3.5 h, the clean addition of NH3 afforded the primary imine 2a, the expected tautomer of the corresponding enamine (Table 1).[17]