Gold-Catalyzed Intermolecular Nitrene Transfer from 2H-Azirines to Ynamides: A Direct Approach to Polysubstituted Pyrroles

Abstract

An effective gold-catalyzed intermolecular nitrene transfer by the reaction of 2H-azirines and ynamides is reported, which provides highly substituted pyrroles in a straightforward manner. This transformation proceeds under mild conditions and gives the polysubstituted pyrroles in good-to-excellent yields. Preliminary results indicate that a nongold carbenoid pathway is preferred for current pyrrole synthesis.

Diversity in Gold‐Catalyzed Formal Cycloadditions of Ynamides with Azidoalkenes or 2H‐Azirines: [3+2] versus [4+3] Cycloadditions

“…Our mechanism opposes the intermediacy of gold carbenes that are postulated by Huang et al 8. because they cannot rationalize products 6 h and 8 e .…”

“…Immediately prior to completion of this work, Huang and co‐workers reported gold‐catalyzed [3+2] formal cycloadditions of 2 H ‐azirines with ynamides to form pyrrole derivatives [Eq. (3)];8 gold carbenes ( III ) were postulated as reaction intermediates. The work of Huang and co‐workers does not reflect the diversity of reactions that can generate products of three types, as depicted in Equations (3)–(5).…”

New regioselective synthesis of polyfunctionalized 3-ferrocenyl-1 H -pyrroles under microwave irradiation

“…The difficulty of obtaining the regioselective pyrrole 3a from diketones, even with the use of catalysts, has been described in the literature. 22h, 31 The synthetic scope of the reaction was expanded to some nonsymmetrical 1,3-dicarbonyl compounds (2b-h) and methyl 2-azido-3-ferrocenyl acrylate (1a), which led to the formation of pyrroles 3b-g, as shown in Table 3. Upon employing trifluoromethyl (2b) or phenyl (2c) substituted 1,3-diketones, poor yields were obtained for the respective pyrroles 3b and 3c (entries 2 and 3).…”

Copper‐Catalyzed Cascade Cyclization for the Synthesis of Trifluoromethyl‐Substituted Spiro‐2H‐azirines from 1,6‐Enynes

“…These butyrolactone skeletons might prove to have some potentialv alue in medicinal chemistry in the future. This copper-catalyzeds ynthesiso fs piro-2H-azirines provedt ob es ynthetically useful to construct complex heterocycles in organic chemistry.F or instance,s piro azirine product 3u was reacted with ynamide 6 in the presence of 3mol% of gold complex M in DCM at 70 8 8Cf or 12 h, [23] the cycloaddition occurred smoothly and gavet he spiro product 7 [20] in 43% yield (Scheme 2).…”