Lithium Diisopropylamide Solvated by Hexamethylphosphoramide: Substrate-Dependent Mechanisms for Dehydrobrominations
作者:Yun Ma、Antonio Ramirez、Kanwal Jit Singh、Ivan Keresztes、David B. Collum
DOI:10.1021/ja060964b
日期:2006.12.1
Lithium diisopropylamide-mediated dehydrobrominations of exo-2-bromonorbornane, 1-bromocyclooctene, and cis-4-bromo-tert-butylcyclohexane were studied in THF solutions and THF solutions with added hexamethylphosphoramide (HMPA). Rate studies reveal a diverse array of mechanisms based on mono-, di-, and trisolvated monomers as well as triple ions. The results are contrasted with analogous eliminations
在四氢呋喃溶液和添加六甲基磷酰胺 (HMPA) 的四氢呋喃溶液中研究了二异丙基氨基锂介导的外-2-溴降冰片烷、1-溴环辛烯和顺-4-溴-叔丁基环己烷的脱溴化氢。速率研究揭示了基于单、二和三溶剂化单体以及三元离子的多种机制。结果与在不存在 HMPA 的情况下在 THF 中的类似消除形成对比。