Synthesis, experimental and theoretical NMR study of 2′-hydroxychalcones bearing a nitro substituent on their B ring
摘要:
The synthesis of several 2'-hydroxynitrochalcones has been accomplished by an aldol reaction of equimolar amounts of the appropriate 2'-hydroxyacetophenones with nitrobenzaldehydes in alkaline medium. The reaction of 2'-hydroxyacetophenones bearing a 6'-methoxy with 2- or 4-nitrobenzaldehydes gave the expected 2'-hydroxynitrochalcones and also 4-methoxynitroaurones, being the latter ones the unique reaction products when using 2 molar equiv of nitrobenzaldehydes. The reaction mechanisms for the formation of both products are discussed. The C-13 NMR chemical shifts have been discussed first by means of an empirical additive model and then by comparison with GIAO/B3LYP calculated absolute shieldings. (C) 2004 Elsevier Ltd. All rights reserved.
Efficient Synthesis of Nitroflavones by Cyclodehydrogenation of 2′-Hydroxychalcones and by the Baker-Venkataraman Method
作者:Ana I. R. N. A. Barros、Artur M. S. Silva
DOI:10.1007/s00706-006-0550-9
日期:2006.12
Several nitroflavone derivatives were synthesized by cyclodehydrogenation of 2'-hydroxychalcones and by the Baker-Venkataraman approach, starting from 2'-hydroxyacetophenones and benzoic acid derivatives. Nitroflavones synthesised by the first synthetic approach were obtained in better global yields than those obtained by the later method. The structures of all new compounds were elucidated by microanalyses, 1D and 2D NMR, IR, and mass spectroscopic measurements.
Reductive Coupling Reactions of 2-Nitrochalcones and their β-Hydroxy-analogues: New Syntheses of 2-Arylquinoline and 2-Aryl-4-hydroxyquinoline Derivatives
作者:Ana I. R. N. A. Barros、André F. R. Dias、Artur M. S. Silva
DOI:10.1007/s00706-007-0647-9
日期:2007.6
A one-pot synthesis of novel 2-arylquinolines and 2-aryl-4-hydroxyquinolines was developed from the intramolecular reductive coupling reactions of 2-nitrochalcones and 3-hydroxy-1-phenyl-3-(2-nitrophenyl)-2-propen-1-ones. Depending on the reduction method and on the presence of electron donating substituents on the A ring of 2-nitrochalcones one can modulate the formation of 2-arylquinolines, their N-oxides, and of 2-aminochalcones. The reduction of 3-hydroxy-1-(2-hydroxyphenyl)-3-(2-nitrophenyl)-2-propen-1-ones with stannous chloride in hydrochloric acid gave 2 '-aminoflavones and with ammonium formate and Pd/C yielded 2-(2-hydroxyaryl)-4-hydroxyquinolines.
One-pot synthesis of 2-(2-hydroxyaryl)quinolines: reductive coupling reactions of 2′-hydroxy-2-nitrochalcones
作者:Ana I.R.N.A Barros、Artur M.S Silva
DOI:10.1016/s0040-4039(03)01374-1
日期:2003.7
A one-pot synthesis of novel 2-(2-hydroxyaryl)quinolines have been developed from the intramolecular reductivecouplingreactions of 2′-hydroxy-2-nitrochalcones, induced by stannous chloride in acidic medium (HCl/AcOH). In some cases these transformations can be performed with ammonium formate/Pd–C in methanol.
Synthesis, experimental and theoretical NMR study of 2′-hydroxychalcones bearing a nitro substituent on their B ring
作者:Ana I.R.N.A. Barros、Artur M.S. Silva、Ibon Alkorta、José Elguero
DOI:10.1016/j.tet.2004.06.005
日期:2004.7
The synthesis of several 2'-hydroxynitrochalcones has been accomplished by an aldol reaction of equimolar amounts of the appropriate 2'-hydroxyacetophenones with nitrobenzaldehydes in alkaline medium. The reaction of 2'-hydroxyacetophenones bearing a 6'-methoxy with 2- or 4-nitrobenzaldehydes gave the expected 2'-hydroxynitrochalcones and also 4-methoxynitroaurones, being the latter ones the unique reaction products when using 2 molar equiv of nitrobenzaldehydes. The reaction mechanisms for the formation of both products are discussed. The C-13 NMR chemical shifts have been discussed first by means of an empirical additive model and then by comparison with GIAO/B3LYP calculated absolute shieldings. (C) 2004 Elsevier Ltd. All rights reserved.