om3010417_si_001.pdf (1.78 MB)

Electrospray Ionization Mass Spectrometry Reveals an Unexpected Coupling Product in the Copper-Promoted Synthesis of Pyrazoles

Download (1.78 MB)
journal contribution
posted on 11.02.2013, 00:00 by Jakub Hyvl, Divya Agrawal, Radek Pohl, Mamta Suri, Frank Glorius, Detlef Schröder
The reaction mechanism of the intermolecular oxidative formation of pyrazole 2 via a C–C/N–N bond-formation cascade of the enaminone 1 is investigated by means of ESI-MS. No direct reaction intermediates are observed; however, the formation of an unexpected imidazolid-3-one derivative X is observed that involves an oxidative dimerization of 1 in the presence of dioxygen. The derivative X is isolated and characterized by means of multidimensional 1H and 13C NMR spectroscopy.