A general synthetic method was developed for 2-aryl-2, 3-dihydrobenzo[b]furans via regioselective lithiation of ortho-tolyl tetramethylphosphorodiamidates followed by addition of aromatic aldehydes as a key step. ortho-Tolyl tetramethylphosphorodiamidates were regioselectively lithiated with sec-BuLi in tetrahydrofuran at -105°C to give benzylic lithio species. The resulting lithio species were reacted with aromatic aldehydes to provide 1, 2-diarylethanolderivatives. Reductive removal of the phosphoryl group with lithium aluminum hydride followed by acidic treatment led to 2-aryl-2, 3-dihydrobenzo[b]furans in good overall yields. The utility of this strategy was demonstrated in regioselective syntheses of highly substituted neolignan natural products, such as (±)-licarin B and (±)-carnatol, starting from O-bis(dimethylamino)phosphorylated eugenol or isoeugenol.
作为关键步骤,通过对原
甲苯基四甲基
磷二酰胺进行区域选择性石化作用,然后加入芳香醛,开发了一种 2-芳基-2,3-二氢苯并[b]
呋喃的通用合成方法。生成的二
硫代
锂与芳香醛反应,得到 1,2-二
硫代
乙醇衍
生物。用
氢化铝锂还原去除
磷基,然后进行酸处理,可得到 2-芳基-2,3-二氢苯并[b]
呋喃,总产率很高。在以 O-双(二甲基
氨基)
磷酸化
丁香酚或
异丁香酚为起始物,对 (±)-licarin B 和 (±)-carnatol 等高度取代的新
木犀草素天然产物进行区域选择性合成时,证明了这一策略的实用性。