Hemilabile ligands in organolithium chemistry: Substituent effects on lithium ion chelation

A Ramírez, E Lobkovsky, DB Collum

Index: Ramirez, Antonio; Lobkovsky, Emil; Collum, David B. Journal of the American Chemical Society, 2003 , vol. 125, # 50 p. 15376 - 15387

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Citation Number: 40

Abstract

The lithium diisopropylamide-mediated 1, 2-elimination of 1-bromocyclooctene to provide cyclooctyne is investigated using approximately 50 potentially hemilabile polyethers and amino ethers. Rate laws for selected ligands reveal chelated monomer-based pathways. The dependence of the rates on ligand structure shows that anticipated rate accelerations based on the gem-dimethyl effect are nonexistent and that substituents generally retard ...