Rh(II)-catalyzed Denitrogenative Cascade of 1,2,3-Triazolyl Propiolates and Indoles: Access to Butenolide Tethered Homotryptamines

Rhodium(II)-catalyzed synthesis of 2-aminoquinoline derivatives from 2-quinolones and N-sulfonyl-1,2,3-triazoles

Herein, we disclose a rhodium(II) catalyzed efficient and convenient method for the synthesis of 2-aminoquinoline derivatives from 2-quinolones and N-sulfonyl-1,2,3-triazoles. The reaction provides rapid access to a series of 2-aminoquinolines with moderate to excellent yields. The reaction proceeds via quinolone-hydroxyquinoline tautomerization/O-H insertion to a rhodium(II)-aza vinyl carbene intermediate generated by denitrogenation of triazole followed by rearrangement to deliver the desired product. Furthermore, we demonstrated the iodine-mediated dealkylation of a 2-aminoquinoline derivative.

Rh(II)-Catalyzed Denitrogenative Reaction of N-Sulfonyl-1,2,3-triazoles with Quinolones and Isoquinolones

Herein, we developed an efficient approach to access biologically relevant 2-aminoquinolines and 1-aminoisoquinolines from readily available N-sulfonyl-1,2,3-triazoles and 2-quinolones or 1-isoquinolones. This transformation involves the selective O-H insertion of these derivatives onto the in situ generated Rh-azavinyl carbenes (Rh-AVC) followed by rearrangement. The reaction proceeds smoothly under operationally simple conditions and the protocol was found to be scalable.

Annulation-Triggered Denitrogenative Transformations of 2-(5-Iodo-1,2,3-triazolyl)benzoic Acids

The ability of [1,2,3]triazolobenzoxazinones to act as a source of "hidden" diazo group was discovered. These diazo precursors can be easily prepared by the intramolecular cyclization of 2-(5-iodo-1,2,3-triazolyl)benzoic acids. The Cu-catalyzed capture of the hidden diazo group allows for further functionalization through the denitrogenative pathway. The transformations proceed via the formation of either diazoimine or diazoamide intermediates. Novel routes to various anthranilamides as well as thiolated benzoxazinones were developed using the one-pot cyclization/diazo capture procedure.

Access to tetrahydrocarbazoles and pyrrolo[3,4-b]carbazoles through sequential reactions of triazoles and indoles

Tetrahydrocarbazoles and pyrrolo[3,4-b]carbazoles could be synthesized conveniently through sequential reactions of ester-tethered 1-sulfonyl-1,2,3-triazoles and indoles. The reaction conditions were mild and the procedures were quite simple. Moreover, the key intermediate α,β-unsaturated imine acted as a [2C] synthon in the [4 + 2] cycloaddition reaction, and the imino group could be used as a nucleophile to construct the fourth ring.

Visible-Light-Catalyzed in Situ Denitrogenative Sulfonylation of Sulfonylhydrazones

A photocatalyzed in situ denitrogenative sulfonylation of N-arylsulfonyl hydrazones has been developed. This transformation provides a low-carbon strategy to assemble arylalkyl sulfones in a stepwise denitrogenation/sulfonylation manner.

Rhodium-Catalyzed Synthesis of 2-Aroylpyrimidines via Cascade Heteropolyene Rearrangement

A one-step synthesis of cytotoxic 2-aroylpyrimidines by the denitrogenative reaction of 1-tosyl-1,2,3-triazoles with isoxazoles under rhodium catalysis has been developed. According to the density functional theory calculations and control experiments, the disclosed reaction proceeds via the rearrangement of an oxadiazatetraene intermediate involving a cascade of intramolecular aza-Diels-Alder and retro-aza-Diels-Alder reactions. The presence of a substituent at C4 of the isoxazole is a prerequisite for the formation of the pyrimidines.