A process involving gold(I)-catalyzed formal double hydroamination of alkynes, bearing a tethered carboxylic group, for the synthesis of fused dihydrobenzimidazoles and tetrahydroquinazolines has been developed. A series of transition metal catalysts have been screened for this transformation, and a catalyst system consisting of Ph(3)PAuCl (1 mol %) and AgOTf (1 mol %) was found to be the best. The procedure entails the reaction of easily accessible starting materials such as alkynoic acids and 1,2-diaminobenzenes/2-aminobenzylamines in the presence of the catalyst in 1,2-dichloroethane at 100 degrees C. In the case of alpha-substituted alkynoic acids, the corresponding products were obtained in high diastereoselectivities; the structure of the diastereomers has been unambiguously characterized by NMR techniques. The mechanism of the reaction is discussed, and the origin of the diastereoselectivities is addressed. It was observed that under the microwave irradiation conditions, the reaction time is significantly shortened (0.5 h).

An efficient method for formal Markownikoff hydroamination/hydroarylation and double hydroamination of terminal alkynes has been developed. For example, treatment of terminal alkynes with amino‐aromatics or diamines in the presence of 2–5 mol‐% of Ph3PAuNTf2 in toluene at 100 °C gave the corresponding products in excellent yields. The method was shown to be applicable to a broad range of substrates and, more importantly, unlike our previously reported method, a tethered hydroxy group in the alkyne is not necessary. The mechanism of the reaction is also discussed.

A gold(I)-catalyzed, operationally simple coupling-cyclization technique was developed for the synthesis of isoquinoline-fused polycyclic compounds. The reaction makes use of two coupling partners such as o-alkynylbenzaldehydes and aromatic amines having tethered nucleophiles. The reaction

A robust library‐based approach to new fused quinazolinones by the development of gold(I)‐catalyzed cascade reactions between 2‐aminobenzohydrazides and alkynoic acids is documented. Selected compounds were administered to lung (A549) and breast cancer cells (MDA‐MB‐231 and MCF‐7) in vitro and it was found that some successfully inhibited cell proliferation.

A wide range of terminal alkynes smoothly undergoes hydroamination—hydroarylation reaction in the presence of a thermally stable cationic Au catalyst to give fused dihydropyrazines (III), (V), (VII) or fused dihydroquinolines (IX), (XI).