Divergent reactivities of o-haloanilides with CuO nanoparticles in water: a green synthesis of benzoxazoles and o-hydroxyanilides
作者:Nilufa Khatun、Srimanta Guin、Saroj Kumar Rout、Bhisma K. Patel
DOI:10.1039/c3ra46820h
日期:——
In the present study, three divergent reaction paths emerged when o-haloanilides were subjected to CuO nanoparticles in water. o-Halo (I, Br) phenylbenzamides in the presence of CuO nanoparticles and Cs2CO3 in water at 100 °C provided o-hydroxyphenyl benzamides as the major product. However, a complete change in selectivity was observed in the presence of an organic base/ligand (TMEDA), giving 2-arylbenzoxazole as the exclusive product. The above selectivities were not clearly distinct when the corresponding alkylamides were treated either in the presence or absence of the ligand. A number of o-halophenyl alkylamides provided either exclusively o-dehalogenated products or a mixture of o-dehalogenated and o-hydroxylated products, but none gave 2-alkylbenzoxazoles. In addition to the above selectivities, the use of an environmentally friendly solvent (water) and base, and the recyclability of the catalyst make this procedure a benign alternative to the existing methods for the synthesis of these molecules, viz. o-hydroxybenzamides and o-arylbenzoxazoles.
Electrochemical synthesis of benzoxazoles from anilides – a new approach to employ amidyl radical intermediates
作者:Tile Gieshoff、Anton Kehl、Dieter Schollmeyer、Kevin D. Moeller、Siegfried R. Waldvogel
DOI:10.1039/c7cc00927e
日期:——
A novel electrochemical method for the synthesis of benzoxazoles from readily available anilides is reported. Various functionalities are tolerated and good yields can be achieved. By employing common electrode materials...