Rearrangements of N-alkyl-/aryl-nitrones derived from 4-oxo-4H-1-benzopyran-3-carboxaldehyde––a solvent-dependent process
作者:Tarun Ghosh、Chandrakanta Bandyopadhyay
DOI:10.1016/j.tetlet.2004.06.033
日期:2004.8
C-(4-Oxo-4H-1-benzopyran-3-yl)-N-alkyl-/aryl-nitrones derived from 4-oxo-4H-1-benzopyran-3-carboxaldehyde, rearrange to 2-alkyl-/aryl-amino-3-formylchromone and/or 3-(alkyl-/aryl-aminomethylene)chroman-2,4-dione depending upon the reaction medium. 3-(Alkylaminomethylene)chroman-2,4-dione has been utilized in the synthesis of 1-benzopyrano[3,4-d]isoxazole-4-one. (C) 2004 Elsevier Ltd. All rights reserved.
An organocatalytic rearrangement of 2-(N-alkyl-/aryl-)amino-4-oxo-4H-1-benzopyran-3-carbaldehyde
2-(Arylamino)-4-oxo-4H-1-benzopyran-3-carbaldehyde rearranges to 4-oxo-4H-1-benzopyran-3-carbanilide when treated with glycine in the presence of formalin, but under similar conditions 2-(alkylamino)-4-oxo-4H-1-benzopyran-3-carbaldehyde rearranges to 3-alkylaminomethylenechroman-2,4-dione. (C) 2011 Elsevier Ltd. All rights reserved.