Complex-induced proximity effects in proton transfer and halogen-metal exchange reactions

Reactions in which there is formal intramolecular transfer of an acidic deuterium to a site of halogen-lithium exchange could be interpreted to show that initial halogen-lithium exchange occurs faster than loss of the acidic deuterium. However studies of the competition between halogen-metal exchange and deuterium loss for $N$-deutero-$N$-alkyl-2-, 3-, and 4-halobenzamides (39a-f) are not consistent with that mechanism. An alternative mechanism in which initial loss of the acidic deuterium is followed by halogen-lithium exchange to give a dilithiated intermediate (41) is suggested. Deuterium transfer to the site of halogen-lithium exchange then occurs by intermolecular reaction of the dilithiated species with unreacted $N$-deuterated amide as it diffuses into the solution. The halogen-lithium exchange is faster than complete mixing of the reactants, and can occur either in an initially formed deprotonated complex or in a transient high local concentration of organolithium reagent as the organolithium is added to the amide substrate. Differentiation between these two possibilities is achieved by employing reverse addition of the amide substrate to a solution of the organolithium reagent. In cases where halogen-lithium exchange occurs through a complex, no change in product ratios is observed.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Musick, Timothy Joseph

Contributors dc:contributor

• Beak, Peter

• Chemistry, Organic

Statement dc:rights

• Copyright 1989 Musick, Timothy Joseph

Language dc:language

eng

Identifier

AAI9010963
(UMI)AAI9010963

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/20653