Intramolecular zinc-ene reactions of alkynes; preparation of 1,5-annulated 4-methylenecyclopentenes
作者:Jaap van der Louw、Juul L. van der Baan、Corine M.D. Komen、Adri Knol、Franciscus J.J. de Kanter、Friedrich Bickelhaupt、Gerhard W. Klumpp
DOI:10.1016/s0040-4020(01)89858-6
日期:1992.1
Intramolecular Type I zinc-ene reaction of 3-(alk-m-ynyl)-2-(methoxymethyl)-2-propenylzinc bromides 2 (m = 4,5,6) gave five-, six- and seven-membered carbometallation product 3, which on Pd(0)-catalyzed cyclization were converted to 1,5-annulated 4-methylenecyclopentenes 4. Preparation of 4-methylenecyclopentenes by intramolecular Type II zinc-ene reactions of 2-(alk-m-ynyloxymethyl)-2-alkenylzinc
3-(烷基-间-炔基)-2-(甲氧基甲基)-2-丙烯基溴化锌2(m = 4,5,6)的分子内I型锌-烯反应生成五元,六元和七元的碳金属化产物3,其在Pd(0)催化的环化反应中转化为1,5-环化的4-亚甲基环戊烯4。通过2-(烷-间-炔氧基甲基)-2-烯基溴化锌6(m = 2,3)的分子内II型锌-烯反应,然后通过Pd(0)催化的碳金属化产物7的重排,制备4-亚甲基环戊烯不可能。加法和重排很慢或没有发生。