Add time:08/25/2019         Source:sciencedirect.com

Publisher SummaryThis chapter presents the synthesis and chemistry of five-membered ring system containing more than one nitrogen atom. Diazo, diazonium, and azo compounds can be employed as precursors in the preparation of pyrazoles and indazoles. A series of 3-acyl-4-amino-1-aryl-1H-pyrazoles are prepared from the reaction of β-enaminones with aryldiazonium tetrafluoroborates. A series of pyrazoles are prepared in good yields via 1,3-dipolar cycloaddition of diazoacetate compounds to terminal alkynes promoted by Zn(OTf)2 under mild conditions. Readily available 2-chloromethylarylzinc reagents react with aryldiazonium tetrafluoroborates to provide polyfunctional indazoles that undergo selective metalations to produce new polycyclic aromatics. A facile one-pot procedure for the regioselective synthesis of pyrazole-5-carboxylates by 1,3-dipolar cycloaddition of ethyl diazoacetate with diazabicycloundecene (DBU) in acetonitrile with α-methylene carbonyl compounds is described in the chapter. The one-pot synthesis of multisubstituted pyrazole derivatives is achieved via the catalyst-free 1,3-dipolar cycloaddition of ethyl diazoacetate and nitroalkenes as the key step and elimination of a nitro or bromide leaving group followed by intramolecular proton transfer with satisfactory yields.

We also recommend Trading Suppliers and Manufacturers of 2-N-BUTYL-1,3-DIAZA-SPIRO[4,4]NON-1-EN-4-ONE HYDROCHLORIDE (cas 138402-05-8). Pls Click Website Link as below: cas 138402-05-8 suppliers