catalysed oxidative coupling reaction of formamides with β-keto esters and 2-carbonyl-substituted phenols successfully proceeded through directC–Hbondactivation of formamides. The corresponding carbamates were formed with high stereoselectivity under mild reaction conditions. This protocol was successfully applied to the synthesis of three novel halogenated carbamates and a carbaryl insecticide derivative
Copper-Catalyzed Oxidative CO Coupling by Direct CH Bond Activation of Formamides: Synthesis of Enol Carbamates and 2-Carbonyl-Substituted Phenol Carbamates
Formamide CH bondactivation has been achieved under oxidative conditions, using a copper catalyst and tert‐butyl hydroperoxide (TBHP) as the external oxidant (see scheme). This oxidative coupling of a range of dialkyl formamides provides an easy, phosgene‐free route for the selective synthesis of Z‐enol carbamates and 2‐carbonyl‐substituted phenol carbamates in high yields.
The catalytic activity of copper nanoparticles on charcoal (Cu/C) was investigated as an environmentally friendly heterogeneous catalyst for the synthesis of enol carbamates and amides via the oxidative coupling of N,N-dialkyl formamides with 1,3-dicarbonyl compounds and aromatic aldehydes with amine hydrochloride salts, respectively. Various enol carbamates and amides were synthesized in moderate to good yields using this method. Moreover, the catalyst could be recovered and subsequently reused in further reactions. (C) 2015 Elsevier Ltd. All rights reserved.