Aims and Objectives: An efficient and facile DBU catalysed synthesis of highly significant motif 5,7-disubstituted-1,2,4-triazolo[1,5-a]pyrimidines under solvent-free condition has been reported.

Materials and Methods: To a round bottom flask, 1.0 mmol of chalcone (1), 1.5 mmol of 3-amino-1,2,4- triazole (2) and 30 mol% of DBU were added at 70 °C and stirred in solvent-free condition. After the completion of the reaction (monitored by TLC), water (10 ml) was added. The aqueous layer was extracted with ethyl acetate (3 ×10 ml). The combined organic layers were dried over anhydrous Na2SO4. The combined organic layers were evaporated under reduced pressure and the resulting crude product was purified by column chromatography by using ethyl acetate and hexane as eluent.

Results: Reaction using chalcone and 3-amino-1,2,4-triazole as model substrates were carried out under different reaction conditions and it was observed that 30 mol% of DBU under the solvent-free condition at 70 °C was the optimum temperature for the proposed synthesis.

Conclusion: Use of DBU (an organocatalyst) as a base, operational simplicity, high yield of products and short reaction time are some of the significant advantages associated with the proposed strategy.

目的和目标：已经报道了在无溶剂条件下高效且简便的DBU催化合成高度重要的5,7-二取代-1,2,4-三唑并[1,5-a]嘧啶基序。

材料和方法：在70°C下，向圆底烧瓶中加入1.0 mmol的查尔酮（1），1.5 mmol的3-氨基-1,2,4-三唑（2）和30 mol％的DBU。无溶剂条件。反应完成后（通过TLC监测），加入水（10ml）。用乙酸乙酯（3×10ml）萃取水层。合并的有机层经无水Na 2 SO 4干燥。减压蒸发合并的有机层，并将所得粗产物通过柱色谱法纯化，使用乙酸乙酯和己烷作为洗脱剂。

结果：在不同反应条件下，以查耳酮和3-氨基-1,2,4-三唑为模型底物进行反应，观察到70℃无溶剂条件下DBU的最佳用量为30 mol％。建议合成的温度。

结论：以DBU（有机催化剂）为基础，操作简便，产品收率高，反应时间短是所提出策略的一些重要优势。