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
Lithiumdiisopropylamide-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
Enantioselective Preparation of 4-Substituted Cyclohexenes by Radical Fragmentation of Sulfoxides
作者:Christoph Imboden、Félix Villar、Philippe Renaud
DOI:10.1021/ol990859p
日期:1999.9.1
[GRAPHICS]Radical fragmentation of o-bromophenyl sulfoxides is reported. Starting from enantiomerically pure material, 4-substituted cyclohexene derivatives have been prepared with enantiomeric excesses between 70% and 86%, The key step of the process is a diastereoselective abstraction of a hydrogen atom by the initial aryl radical. The highest enantiomeric exesses have been obtained in the presence of aluminum Lewis acids.
SADOZAI S. K.; LEPOIVRE J. A.; DOMMISSE R. A.; ALDERWEIRELDT F. C., BULL. SOC. CHIM. BELG., 1980, 89, NO 8, 637-642
作者:SADOZAI S. K.、 LEPOIVRE J. A.、 DOMMISSE R. A.、 ALDERWEIRELDT F. C.