Efficient tandem synthesis of a variety of pyran-annulated heterocycles, 3,4-disubstituted isoxazol-5(4H)-ones, and α,β-unsaturated nitriles catalyzed by potassium hydrogen phthalate in water
作者:Hamzeh Kiyani、Fatemeh Ghorbani
DOI:10.1007/s11164-014-1863-7
日期:2015.10
A variety of 4H-chromenes, benzochromenes, 4,5-dihydropyrano[3,2-c]chromenes, 4H-pyran-3-carboxylates, and 3,4-disubstituted isoxazol-5(4H)-ones have been synthesized in high yields by using potassium hydrogen phthalate (KHP) as an inexpensive, commercially available catalyst. It was found that the three-component tandem reaction enabled synthesis of pyran-annulated heterocycles in water at 50 °C. 3,4-Disubstituted isoxazol-5(4H)-ones were synthesized by use of 10 mol% KHP in water at room temperature. Also, treatment of methylene-containing compounds (malononitrile or ethyl cyanoacetate) with aromatic aldehydes in the presence of 5 mol% KHP resulted in α,β-unsaturated nitriles. The procedure is an easily performed, straightforward method for synthesis of a variety of pyran-annulated compounds, isoxazol-5(4H)-one-containing heterocycles, and Knoevenagel adducts. The reaction is safe, uses mild conditions, and is environmentally benign. Other notable advantages are reuse of the catalyst, no use of hazardous organic solvents, and ease of work-up.
合成了一系列4H-克罗梅、苯并克罗梅、4,5-二氢吡喃[3,2-c]克罗梅、4H-吡喃-3-羧酸盐以及3,4-二取代的异噁唑-5(4H)-酮,采用了氢钾邻苯二甲酸盐(KHP)作为廉价的商业可得催化剂,得到了高产率。研究发现,这种三组分串联反应使得在50°C的水相中合成了吡喃环接合的杂环化合物。3,4-二取代的异噁唑-5(4H)-酮是在室温下使用10 mol% KHP水相合成的。此外,在存在5 mol% KHP的情况下,采用含亚甲基的化合物(如马来腈或乙基氰乙酸酯)与芳香醛的反应,得到了α,β-不饱和腈。该方法是一种简单易行的合成多种吡喃环接合化合物、含异噁唑-5(4H)-酮的杂环化合物和Knoevenagel加成物的直截了当的方法。该反应安全、条件温和且环境友好。其他显著优点包括催化剂的重复使用、不使用有害有机溶剂以及简便的后处理。