Reductive lithiation of cyclic benzofused ethers: a source of oxygen-functionalised organolithium compounds
作者:Miguel Yus、Francisco Foubelo、José V Ferrández、Abderrazak Bachki
DOI:10.1016/s0040-4020(02)00434-9
日期:2002.6
of an electrophile [E+=H2O, tBuCHO, PhCH2CHO, Ph(CH2)2CHO, PhCHO, furfural, Me2CO, Et2CO, cyclopentanone, cyclohexanone, cyclooctanone, (−)-menthone] in THF at −78°C gives, after hydrolysis, compounds 3. Some diols 3 are easily transformed into 2-substituted chromans 6 under acidic reaction conditions. The reductive lithiation of chroman (7) at 20°C for 3 h leads exclusively to the intermediate 8,
2,3-二氢苯并呋喃(1)与锂和催化量的4,4'-二叔丁基联苯(DTBB,5%)在THF中于0°C反应1.5 h,然后添加亲电试剂THF中的[E + = H 2 O,t BuCHO,PhCH 2 CHO,Ph(CH 2)2 CHO,PhCHO,糠醛,Me 2 CO,Et 2 CO,环戊酮,环己酮,环辛酮,(-)-薄荷酮]水解后,-78℃得到化合物3。一些二醇3在酸性反应条件下容易转化为2-取代的苯并吡喃6。苯并二氢吡喃的还原锂化7)在20°C下反应3小时,仅生成中间体8,该中间体8是通过脱芳基形成的,并异构化为表面上更稳定的苄基中间体9。这些中间体与不同的亲电试剂E + = t BuCHO,PhCHO,糠醛,Me 2 CO,[CH 3(CH 2)4 ] 2 CO,环戊酮,环己酮,(-)-薄荷酮,Ph 2 CO}的反应,在-78℃下于THF中在水解后,导致区域异构体10和11的混合物。2,