829-31-2Relevant articles and documents
Exploiting Synergistic Catalysis for an Ambient Temperature Photocycloaddition to Pyrazoles
Lakeland, Christopher P.,Watson, David W.,Harrity, Joseph P. A.
, p. 155 - 159 (2019/12/11)
Sydnone-based cycloaddition reactions are a versatile platform for pyrazole synthesis, however they operate under harsh conditions (high temperature and long reaction times). Herein we report a strategy that addresses this limitation utilizing the synergistic combination of organocatalysis and visible-light photocatalysis. This new approach proceeds under ambient conditions and with excellent levels of regiocontrol. Mechanistic studies suggest that photoactivation of sydnones, rather than enamines, is key to the successful implementation of this process.
Ultrafast Click Chemistry with Fluorosydnones
Liu, Hui,Audisio, Davide,Plougastel, Lucie,Decuypere, Elodie,Buisson, David-Alexandre,Koniev, Oleksandr,Kolodych, Sergii,Wagner, Alain,Elhabiri, Mourad,Krzyczmonik, Anna,Forsback, Sarita,Solin, Olof,Gouverneur, Véronique,Taran, Frédéric
, p. 12073 - 12077 (2016/11/16)
We report the synthesis and reactivity of 4-fluorosydnones, a unique class of mesoionic dipoles displaying exquisite reactivity towards both copper-catalyzed and strain-promoted cycloaddition reactions with alkynes. Synthetic access to these new mesoionic compounds was granted by electrophilic fluorination of σ-sydnone PdIIprecursors in the presence of Selectfluor. Their reactions with terminal and cyclic alkynes were found to proceed very rapidly and selectively, affording 5-fluoro-1,4-pyrazoles with bimolecular rate constants up to 104m?1s?1, surpassing those documented in the literature with cycloalkynes. Kinetic studies were carried out to unravel the mechanism of the reaction, and the value of 4-fluorosydnones was further highlighted by successful radiolabeling with [18F]Selectfluor.
Synthesis of 2 H-indazoles by the [3 + 2] dipolar cycloaddition of sydnones with arynes
Fang, Yuesi,Wu, Chunrui,Larock, Richard C.,Shi, Feng
, p. 8840 - 8851 (2012/01/02)
A rapid and efficient synthesis of 2H-indazoles has been developed using a [3 + 2] dipolar cycloaddition of sydnones and arynes. A series of 2H-indazoles have been prepared in good to excellent yields using this protocol, and subsequent Pd-catalyzed coupl