The reaction of various 4-hydroxy-2H-[1]benzopyran-2-ones 1 with allyl bromide and potassium carbonate in acetone yielded the corresponding 4-allyloxy derivatives 2. Claisen rearrangement of 2 gave 3-allyl-4-hydroxy-2H-[1]benzopyran-2-ones 3, which were reacted with sodium hydroxide to give the sodium benzopyranolate salt 4. Oxidative cyclization of 4 with equimolar quantities of dichlorobis(benzonitrile)palladium gave a 1:1 mixture of 2-methyl-4H-furo[3,2-c][1]benzopyran-4-ones 5 and 2H,5H-pyrano[3,2-c]-[1]benzopyran-5-ones 6, in 88-90% combined yield.
各种 4- 羟基-2H-[1]苯并
吡喃-2-酮 1 与烯丙基
溴和
碳酸钾在
丙酮中反应,得到相应的 4- 烯丙氧基衍
生物 2。 2 的克莱森重排反应得到 3-烯丙基-
4-羟基-2H-[1]苯并
吡喃-2-酮 3,与
氢氧化钠反应得到苯并
吡喃酸钠盐 4。 4 与等摩尔量的二
氯双(
苯甲腈)
钯发生氧化环化反应,得到 1:1 的 2-甲基-4H-
呋喃并[3,2-c][1]苯并
吡喃-4-酮 5 和 2H,5H-
吡喃并[3,2-c]-[1]苯并
吡喃-5-酮 6 的混合物,总收率为 88-90%。