Synthesis of Functionalized 4<i>H</i>-Pyrano[3,2-<i>c</i>]pyridines from 4-Hydroxy-6-methyl-2-pyridone and Their Reactions. Unexpected New Routes to 3,3′-Benzylidenebis[4-hydroxy-6-methyl-2(1<i>H</i>)-3-pyridinone]s
作者:Ramadan Ahmed Mekheimer、Nabil Helmi Mohamed、Kamal Usef Sadek
DOI:10.1246/bcsj.70.1625
日期:1997.7
The reaction of 4-hydroxy-6-methyl-2-pyridone 1 with benzylidenemalononitriles in an ethanolic solution containing a catalytic amount of piperidine and α-cyanoacrylic esters in pyridine affords the corresponding 4H-pyrano[3,2-c]pyridines. However, it’s reaction with 3-(cyanomethylene)-2-indolinones gives either 2-amino-3-quinolinecarbonitriles or ethyl 2-amino-5′,6′-dihydro-7′-methyl-2,5′-dioxospiro-[indoline-3,4′-[4H]-pyrano[3,2-c]pyridine-3′-carboxylate. In contrast, the reaction of 1 with 3-aryl-2-cyano-2-propenethioamides affords 3,3′-benzylidenebis[4-hydroxy-6-methyl-2(1H)-3-pyridinone]s. The reaction of the obtained 4H-pyrano[3,2-c]pyridines with acetic anhydride affords the corresponding fused system.
4- 羟基-6-甲基-2-吡啶酮 1 与苯亚甲基丙二腈在含有一定量哌啶和 α-氰基丙烯酸酯催化剂的吡啶乙醇溶液中反应,生成相应的 4H-吡喃并[3,2-c]吡啶。然而,它与 3-(氰基亚甲基)-2-吲哚啉酮反应会生成 2-氨基-3-喹啉甲腈或 2-氨基-5′,6′-二氢-7′-甲基-2,5′-二氧杂螺-[吲哚啉-3,4′-[4H]-吡喃并[3,2-c]吡啶-3′-羧酸乙酯。与此相反,1 与 3-芳基-2-氰基-2-丙烯硫酰胺反应生成 3,3′-亚苄基双[4-羟基-6-甲基-2(1H)-3-吡啶酮]。将得到的 4H-吡喃并[3,2-c]吡啶与乙酸酐反应,可得到相应的融合体系。