A mild and efficient reaction of the Bestmann-Ohira reagent with N-unprotected isatin-derived olefins has been developed for the selective synthesis of spiro-pyrazoline-oxindoles and tricyclic pyrazoles. The reaction features an attractive product-selectivity depending on the substituent on isatin-derived olefin. Treatment of 3-aryl/alkylideneoxindoles with BOR afforded spiropyrazoline-oxindoles, whereas 3-phenacylideneoxindoles furnished pyrazoloquinazolinones via a unique ring expansion reaction.

A general method for the construction of trifluoromethylated 2‐quinolinones has been established herein by using a trifluoromethylative ring expansion of isatin with trifluorodiazoethane. The strategy provides a platform for the rapid synthesis of a wide range of substituted 3‐hydroxy‐4‐trifluoromethyl‐2‐quinolinones. This operationally simple and robust Ag‐catalyzed protocol successfully transforms isatin ketimines to 3‐amino‐4‐trifluoromethylquinolinones in excellent yields. The utility of this novel method is further illustrated by the conversion of the products into various synthetically and medicinally relevant molecules.

An efficient, metal-free decarbethoxylative arylation protocol for the synthesis of α-aryl-α-fluoroamides from fluoromalonamates, under ambient reaction conditions using aryne as an electrophilic arylating agent, is reported. This decarbethoxylative arylation proceeds under mild conditions and provides a practical and effective entry to a wide range of α-aryl-α-fluoroacetamides. Interestingly, the use of the tert-butyl ester of fluoromalonamate prevented the otherwise rapid decarboxylation step, affording the arylated fluoromalonamate in moderate yield.

An efficient additive-free three-component access to densely functionalized isoxazolidines using diazo compounds, nitrosoarene, and allenic esters has been uncovered.

An efficient three-component protocol for the synthesis of trifluoromethylated spiro-isoxazolidine-oxindoles has been developed. This approach employs the 1,3-dipolar cycloaddition of trifluoromethyl nitrone, generated in situ from trifluorodiazoethane and nitrosoarene, with phenacylideneoxindoles. A range of phenacyclideneoxindoles and nitrosoarenes can be subjected to this reaction to generate the spiro-isoxazolidine-oxindole derivatives. The reductive ring-opening reaction of isoxazolidines carried out to demonstrate the synthetic potential of our strategy resulted in an interesting rearrangement to yield pyrroloquinoline derivatives.