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。