Beilstein J. Org. Chem.2021,17, 1335–1351, doi:10.3762/bjoc.17.93
”, formally an internal redox reaction where the heterocyclic system is oxidatively aromatized and one of the substituents at C-4 reductively lost as a hydrocarbon. The reaction involves the treatment of a ketone with a solution of ethylcyanoacetate in ethanolic ammonia [7]. A precipitate of the ammonium salt
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Graphical Abstract
Figure 1:
Icilio Guareschi (1847–1918). (Source: Annali della Reale Accademia di Agricoltura di Torino1919, ...
Beilstein J. Org. Chem.2010,6, 1056–1060, doi:10.3762/bjoc.6.120
derivatives of 1,3-diarylthiobarbituric acids (DTBA) with active methylene compounds, such as malononitrile and ethyl cyanoacetate, in presence of ZnCl2 has been developed.
Keywords: benzenoid; ethylcyanoacetate; malononitrile; pyrimidine; 2-thioxoquinazolin-4-ones; Introduction
Quinazolines and derivatives
active methylene compounds, such as, malononitrile and ethylcyanoacetate.
Results and Discussion
DTBA are among the simplest synthetic intermediates and can be easily prepared in a one-pot reaction by treating 1,3-diaryl thioureas with malonic acid in the presence of acetyl chloride. DTBA undergoes
gave quinazolines and no other products were detected. In addition, this proposed mechanism was also confirmed from the literature [30][31].
The reaction of 5-ethoxymethylene-1,3-diaryl-2-thiobarbituric acids 1 with ethylcyanoacetate in presence of ammonium acetate and acetic acid with ZnCl2 as a
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Graphical Abstract
Scheme 1:
Synthesis of 2, reagents and conditions: (i) CH2(CN)2, NH4OAc/AcOH, reflux, ZnCl2 (ii) H+/H2O.