Copper-catalyzed regioselective [3+2] annulation of malonate-tethered acyl oximes with isatins

Abstract

A copper-catalyzed regioselective [3 + 2] annulation of malonate-tetherd acyl oximes with isatins was developed, affording valuable 2,3-dihydrooxazole-spirooxindoles in moderate to good yields with excellent diastereoselectivity. The reaction sequence involves...

Copper-Catalyzed Three-Component Cascade Annulation for Divergent Syntheses of Imidazoles and Dihydroimidazoles

“…Inspired by this work, we wondered whether it would be possible to use α , β -unsaturated ketoximes, paraformaldehyde, and amines to synthesize new N -heterocycles. As part of our ongoing efforts to develop oxime acetates involved coupling reactions, herein we disclose the first copper-catalyzed three-component cascade annulation for the divergent syntheses of imidazoles and dihydroimidazoles by the key control of reaction conditions (Scheme b).…”

Copper-catalyzed [4+2] oxidative annulation of α,β-unsaturated ketoxime acetates with ethyl trifluoropyruvate

“…12 Most recently, we successively disclosed the synthesis of dihydrooxazoles by copper-catalyzed cyclization of malonate-tethered acyl oximes and α,β-unsaturated ketoximes with activated ketones, respectively (Schemes 1c and d). 13 Nevertheless, these methods are limited to the construction of five-membered hetercycles through the [3+2] annulation pathways, while [4+2] annulation reaction is yet to be studied. Following our continuous interest in the synthetic applications of oxime acetates, 14 we herein report a [4+2] oxidative annulation of α,β-unsaturated ketoximes with ethyl trifluoropyruvate for regioselective synthesis of trifluoromethyl-containing 2 H -1,3-oxazines (Scheme 1e).…”