Copper-Catalyzed Oxidative Coupling of Formamides with Salicylaldehydes: Synthesis of Carbamates in the Presence of a Sensitive Aldehyde Group
作者:Balaji D. Barve、Yang-Chang Wu、Mohamed El-Shazly、Da-Wei Chuang、Yuan-Bin Cheng、Jeh-Jeng Wang、Fang-Rong Chang
DOI:10.1021/jo402798k
日期:2014.4.4
A diverse library of novel carbamates was synthesized utilizing copper-catalyzed oxidative C-O coupling of formamides and salicylaldehydes. Sensitive aldehyde groups remained intact in the presence of an oxidant and a transition-metal salt. Salicylaldehydes bearing electron-donating, electron-withdrawing, and halogen groups as well as 1-hydroxy-2-naphthaldehydes provided the desired carbamates in good to excellent yields.
Copper-Catalyzed Cross Dehydrogenative Coupling of<i>N</i>,<i>N</i>-Disubstituted Formamides and Phenols: A Direct Access to Carbamates
作者:Wajid Ali、Saroj K. Rout、Srimanta Guin、Anju Modi、Arghya Banerjee、Bhisma K. Patel
DOI:10.1002/adsc.201400659
日期:2015.2.9
AbstractAn efficient copper‐catalyzed protocol has been developed for the synthesis of carbamates from dialkylformamides and phenols possessing directing groups such as benzothiazole, quinoline and formyl at the ortho‐position. In this chelation assisted approach, CO bond formation takes place via a cross dehydrogenative coupling (CDC) between the formyl CH of dialkylformamide and phenolic OH in the presence of copper(II)acetate/aqueous tert‐butyl hydroperoxide. Under identical reaction conditions, salicylic acid derivatives underwent amidation with the carboxylic group rather than formamidation of the phenolic OH. The use of a cheap and environmentally benign catalyst along with the tolerance of a wide range of functional groups makes this an easy, phosgene‐free route to carbamates.magnified image