6-Acetyl-2,2-dimethylchromenes when separately condensed with p-anisaldehyde in the presence of ethanolic NaOH and subsequently oxidized with alkaline hydrogen peroxide without isolating the intermediate chalcones afforded the corresponding 2,2-dimethyl-2H-pyran-fused flavonols respectvely in good yield. Thus, flavonols having free 3-hydroxyl and fused with 2,2-dimethyl-2H-pyran can be synthesized easily.
在
乙醇 NaOH 的存在下,6-乙酰基-2,2-二甲基苯并
吡喃分别与对
甲氧基苯甲醛缩合,然后用碱性
过氧化氢氧化,在不分离中间
查耳酮的情况下,可以得到相应的 2,2-二甲基-
2H-吡喃融合的
黄酮醇,收率很高。因此,具有游离 3- 羟基并与 2,2-二甲基-
2H-吡喃融合的
黄酮醇可以很容易地合成。