yl)‐1‐bromobenzenes 1. Successive treatment of these bromo styrenes with BuLi and 1‐formylpiperidine gave a mixture of (E)‐ and (Z)‐2‐(1‐aryl‐2‐methoxyethenyl)benzaldehydes 2. Hydrolysis of (Z)‐isomers with conc. HBr, followed by pyridinium chlorochromate (PCC) oxidation of the resulting 1H‐2‐benzopyran‐1‐ol derivatives 4 (and 5), afforded the desired products.
由2-(1-芳基-2-甲氧基
乙烯基)-1-
溴苯1制备4-芳基
香豆素(= 4-芳基-1 H --2-苯并
吡喃-1-酮)6。用BuLi和1-甲酰基
哌啶连续处理这些
溴苯乙烯,得到(E)-和(Z)-2-(1-芳基-2-甲氧基
乙烯基)
苯甲醛的混合物2。(Z)-异构体的
水解 用HBr进行氧化,然后将所得的1 H -2-苯并
吡喃-1-醇衍
生物4(和5)氧化
氯铬酸吡啶鎓(
PCC ),得到所需的产物。