A catalyst- and solvent-free protocol for the sustainable synthesis of fused 4<i>H</i>-pyran derivatives
作者:Md. Musawwer Khan、Sumbulunnisan Shareef、Saigal Saigal、Subash C. Sahoo
DOI:10.1039/c9ra04370e
日期:——
An efficient and cost-effective method was developed for the synthesis of two kinds of fused 4H-pyran derivatives, namely, dihydropyrano[2,3-c]pyrazole 4 and pyrano[3,2-c]chromenone 6. The reactions of 3-methyl-1-phenyl-5-pyrazolone/4-hydroxycoumarin with aromatic aldehydes and (E)-N-methyl-1-(methylthio)-2-nitroethenamine (NMSM), involving the Knoevenagel, Michael-addition, O-cyclization and elimination
开发了一种高效且经济有效的方法来合成两种稠合的 4 H-吡喃衍生物,即二氢吡喃并[2,3- c ]吡唑4和吡喃并[3,2- c ]色烯酮6。3-甲基-1-苯基-5-吡唑啉酮/4-羟基香豆素与芳香醛和( E ) -N-甲基-1-(甲硫基)-2-硝基乙烯胺(NMSM)的反应,包括Knoevenagel, Michael-加成,在加热下发生O-环化和消除反应,得到所需产物。合成的化合物通过标准光谱技术进行表征。此外,吡唑稠合 4 H-吡喃的结构通过单晶XRD分析证实了4a和香豆素稠合的4 H-吡喃6b 。反应时间短、收率良好、无需使用昂贵的金属和有毒催化剂或有害有机溶剂以及高原子经济性是该协议的一些值得注意的特点。