A new and facile synthetic approach to substituted 2-thioxoquinazolin-4-ones by the annulation of a pyrimidine derivative

• Nimalini D. Moirangthem and
• Warjeet S. Laitonjam

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

• catalyst afforded 7-hydroxy-2,3-dihydro-2-thioxo-1,3-diarylquinazolin-4(1H)-ones 3 in 76–87% overall yields (Scheme 3) [32][33] and these results are listed in Table 4. Conclusion The cyclocondensation of ethoxymethylene thiobarbituric acids with active methylene compounds under the above noted catalytic

C-Arylation reactions catalyzed by CuO-nanoparticles under ligand free conditions

• Mazaahir Kidwai,
• Saurav Bhardwaj and
• Roona Poddar

Beilstein J. Org. Chem. 2010, 6, No. 35, doi:10.3762/bjoc.6.35

• Mazaahir Kidwai Saurav Bhardwaj Roona Poddar Green Research Laboratory, Department ofChemistry, University of Delhi, Delhi, India 110007 10.3762/bjoc.6.35 Abstract CuO-nanoparticles were found to be an excellent heterogeneous catalyst for C-arylation of active methylene compounds using various

• aryl halides. The products were obtained in good to excellent yield. The catalyst can be recovered and reused for four cycles with almost no loss in activity. Keywords: active methylene compounds; C-arylation; heterogeneous catalyst; recyclability; Introduction Carbon-carbon (C–C) bond formation is

Synthesis of some novel annulated pyrido[2,3-d]pyrimidines via stereoselective intramolecular hetero Diels–Alder reactions of 1-oxa-1,3-butadienes

• Mohit L. Deb and
• Pulak J. Bhuyan

Beilstein J. Org. Chem. 2010, 6, No. 11, doi:10.3762/bjoc.6.11

• lone pair on the allyl nitrogen through the formyl group which makes it less electrophilic towards the active methylene compounds. However, the use of a stronger base, e.g. N,N-diisopropylethylamine (DIPEA) under refluxing conditions in ethanol for 3 h gave quite satisfactory results in all cases. In

Hydroxyapatite supported caesium carbonate as a new recyclable solid base catalyst for the Knoevenagel condensation in water

• Monika Gupta,
• Rajive Gupta and
• Medha Anand

Beilstein J. Org. Chem. 2009, 5, No. 68, doi:10.3762/bjoc.5.68

• catalytic activity was observed which may be attributed to the microscopic changes in the structure of the catalyst. Conclusion An efficient Knoevenagel condensation was achieved between a range of aromatic aldehydes and active methylene compounds in short time periods by using HAP–Cs2CO3 as the catalyst

The tert- amino effect in heterocyclic chemistry: Synthesis of new fused pyrazolinoquinolizine and 1,4-oxazinopyrazoline derivatives

• Dipak Prajapati and
• Kalyan Jyoti Borah

Beilstein J. Org. Chem. 2007, 3, No. 43, doi:10.1186/1860-5397-3-43

• effect, which generalizes cyclization of certain derivatives of 3-methyl-1-phenyl-2-pyrazolin-5-ones. Using this strategy a variety of fused heterocycles is obtained by the Knoevenagel condensation of 5-tert-amino-3-methyl-1-phenylpyrazolone-4-carboxal-dehyde 3 with active methylene compounds such as