4-dihydrocoumarin. A large difference in product distribution was observed between the two bifunctional reagents. Annelation was favored by the use of 1,4-bis(bromomagnesio))butane, whereas conjugate addition was observed with 1,5-bis(bromomagnesio)pentane and even In the use of 4-methylcoumarin.
1,4-双(
溴镁)
丁烷和1,5-双(
溴镁)
戊烷与
香豆素和6-甲基
香豆素的反应得到了1-(邻羟基
苯乙烯基)环烷醇和4-烷基-3,4-二氢
香豆素的混合物。在两种双功能试剂之间观察到产物分布的巨大差异。使用1,4-双(
溴镁)
丁烷有利于退火,而使用1,5-双(
溴镁)
戊烷甚至在使用4-甲基
香豆素时观察到共轭加成。