Rate studies of the dehydrobromination of cycloalkylhalides by lithium diisopropylamide solvated by hexamethylphosphoramide

ORGN 28

Yun Ma and David B. Collum. Department of Chemistry and Chemical Biology, Cornell University, Baker Lab. Box 144, Ithaca, NY 14850
Mechanistic studies of the dehydrobromination mediated by lithium diisopropylamide (LDA) in THF and THF/HMPA reveal that the elimination proceeds via trisolvated monomers and triple ions, respectively. The dehydrobromination of cis- 4-tert-butylcyclohexylbromide is dramatically accelerated by HMPA, whereas the trans-4-tert-butylcyclohexylbromide does not react. The dehydrobrominations proceed by a trans-diaxial elimination.

 

Metal-Mediated Reactions and Syntheses
8:00 AM-12:00 PM, Sunday, August 22, 2004 Pennsylvania Convention Center -- 201B, Oral

Division of Organic Chemistry

The 228th ACS National Meeting, in Philadelphia, PA, August 22-26, 2004