Formation and Intramolecular Capture of α-Imino Gold Carbenoids in the Au(I)-Catalyzed [3 + 2] Reaction of Anthranils, 1,2,4-Oxadiazoles, and 4,5-Dihydro-1,2,4-Oxadiazoles with Ynamides

α-Imino gold carbenoid species have been recognized as key intermediates in a plethora of processes involving gold-activated alkynes. Here, we explored the pathways Au(I)-catalyzed [3 + 2] reaction between mild nucleophiles: anthranil, 1,2,4-oxadiazole, or 4,5-dihydro-1,2,4-oxadiazole, and an ynamide, PhC≡C-N(Ts)Me, proceeding via formation aforementioned α-imino carbene intermediate which, after intramolecular capture, regioselectively produces 2-amino-3-phenyl-7-acyl indoles, N-acyl-5-aminoimidazoles, N-alkyl-4-aminoimidazoles, respectively. In all cases, regioselectivity substituents at 2, 3 7-acyl-indole ring 4, 5 substituted imidazole is decided first transition state, attack nitrogen on C1 C2 carbon activated ynamide. A subsequent steep energy drop furnishes carbene. These features are more pronounced for anthranil 4,5-dihydro-1,2,4-oxadiazole reactions. Strikingly, significant due to unstable carbene, which spontaneous benzaldehyde elimination converted stabilized one. Compared 1,2,4-oxadiazoles 4,5-dihydro-1,2,4-oxadiazoles found be significantly complex than anticipated original research. For instance, compared five-member from one competitive route involves consisting four-member condensed with three-member ring, metathesis expansion led ring.