Rapid and efficient microwave assisted method for the regioselective synthesis of 8,8′-methylene-bis-4-oxo-1H and 2H-chromeno[4,3-C]pyrazoles
作者:Adki Nagaraj、Cherkupally Sanjeeva Reddy
DOI:10.1002/jhet.5570440619
日期:2007.11
compound 3 on reacting with ethylacetoacetate yields 6,6′-methylenebis-(3-acetyl-4-hydroxycoumarin) 4. The compound 4 was regioselectively converted into either 8,8′-methylene-bis-(4-oxo-1H-chromeno[4,3-c]pyrazoles) 6 or 8,8′-methylene-bis(-4-oxo-2H-chromeno[4,3-c]-pyrazoles) 7 under microwave irradiation. High yields are achieved even on a gram scale, while reaction times are considerably shortened compared
的5,5'-亚甲基-双-水杨酸乙酯3是由5,5'-亚甲基-双-水杨酸酯化制备2。与乙酰乙酸乙酯反应的化合物3产生6,6'-亚甲基双-(3-乙酰基-4-羟基香豆素)4。将化合物4区域选择性地转化为8,8'-亚甲基-双-(4-oxo-1 H -chromeno [4,3- c ]吡唑)6或8,8'-亚甲基-双(-4-oxo) -2 H -chromeno [4,3- c ]-吡唑)7在微波照射下。即使以克为单位,也可实现高收率,而与常规加热条件相比,反应时间大大缩短。