An efficient and novel rhodium-catalyzed formal C−O insertion reaction of alkyne-tethered diazo compounds for the synthesis of 3H-indol-3-ols is described. A type of donor/donor rhodium carbene generated in situ via a carbene/alkyne metathesis (CAM) process is the key intermediate and terminates in a unique transformation different from donor/acceptor carbenoids. In addition, 18 O-labeling experiments indicate that intramolecular oxygen-atom transfer from the amide group to the carbon−carbon triple bond occurs during this transformation.

Benzoxazines bearing a C4-quaternary stereocenter have been accomplished via the rhodium-catalyzed electrophilic trapping of zwitterionic intermediates by isatins and imines, respectively. The key intermediates of the strategy are proposed to generate from the reaction of donor−acceptor rhodium carbenes with secondary amides. Usage of chiral BINOL-phosphoric acid co-catalyst resulted in enrichment of enantioselectivity in the trapping process with imines.

A zinc-catalyzed intermolecular alkyne–carbonyl metathesis reaction of ynamides with isatins followed by an amide to ester conversion has been developed, which produces the indolone derivatives with a fully substituted alkene species in good to high yields. The salient features of this reaction include the following: mild reaction conditions, an inexpensive zinc catalyst, a broad substrate scope, the excellent regiocontrol and stereoselectivity, and amenable to the gram scale.

Efficient approach for the facile construction of polyfunctionalized pyrazolone derivatives bearing two contiguous quaternary stereocenters in good yields with high regioselectivities and excellent diastereoselectivities.