The reaction of 2-(N-alkenyl-N-aryl)amino-4-oxo-4H-1-benzopyran-3-carbaldehyde with dimedone/Meldrum’s acid/4-hydroxycoumarin by heating in ethanol in the presence of pyridine produces polycyclicheterocycles bearing pyridine and pyran rings in a one-pot reaction. The effect of substituents on N-atom of the amino function controls the mode of reaction. Terminal alkenes prefer intramolecular Michael
通过在吡啶存在下于乙醇中加热,使2-(N-烯基-N-芳基)氨基-4-氧代-4 H -1-苯并吡喃-3-甲醛与二甲酮/麦德鲁姆酸/ 4-羟基香豆素反应生成多环一锅反应中带有吡啶和吡喃环的杂环。取代基对氨基官能团的N-原子的影响控制了反应方式。末端烯烃偏爱分子内迈克尔型反应,但非末端烯烃偏爱Diels-Alder反应,而在类似条件下,2-(N-烷基-N-烯丙基)氨基-4-氧代-4 H -1-苯并吡喃-3 -甲醛经历多米诺-Knoevenagel-杂Diels-Alder反应。
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.