Organotin-based bifunctional reagents: 4-chloro-2-lithio-1-botene and related substances
作者:Edward Piers、Veranja Karunaratne
DOI:10.1016/0040-4020(89)80019-5
日期:——
transformed into the Grignard reagent 6 or the cuprates 7 and 8. Reagents 6–8 are useful for effecting methylenecyclopentane annulations, as illustrated by the conversions of 31–36 into 43–48, respectively. This novel annulation method played a key role in a total synthesis of the sesquiterpenoid (±)-Δ9(12)-capnellene (55).
4-氯-2-三甲基Canny1-1-丁烯(4)在四氢呋喃(THF)中于-78°C的金属间转移生成4-氯-2-lithio-1-丁烯(5)。在低温下(低于大约-50至-60°C),5可以很好地用作双功能试剂。例如,取决于反应条件,使5与醛和酮反应得到氯醇(例如11、14-18)或取代的3-甲基四氢呋喃(例如19-24)。此外,用试剂5处理α,β-不饱和N,N',N'-三甲基酰肼25-27分别平稳地提供了N,N',N'-三甲基-3-亚甲基环戊烷甲酰肼28-30。硫代试剂5可以很容易地转化为格氏试剂6或铜酸盐7和8。试剂6-8可用于实现亚甲基环戊烷环化,分别由31-36转换为43-48可以说明。这种新颖的环化方法在倍半萜(± ) -Δ9(12) -capnellene(55)的全合成中发挥了关键作用。