Abstract
Halodefluorination of alkyl fluorides using group 13 metal halides has been known
for quite some time (first reported by Newman in 1938) and is often utilized in its
crude stoichiometric form to substitute fluorine with heavier halogens. However, recently
halodefluorination has undergone many developments. The reaction can be effected with
a range of metal halide sources (including s-block, f-block, and p-block metals),
and has been developed into a catalytic process. Furthermore, methods for monoselective
halodefluorination in polyfluorocarbons have been developed, allowing exchange of
only a single fluorine with a heavier halogen. The reaction has also found use in
cascade processes, where the final product may not even contain a halide, but where
the conversion of fluorine to a more reactive halogen is a pivotal reaction step in
the cascade. This review provides a summary of the developments in the reaction from
its inception until now.
1 Introduction
2 Stoichiometric Halodefluorination
2.1 Group 13 Halodefluorination Reagents
2.2 Other Metal Halide Mediated Halodefluorination
3 Catalytic Halodefluorination
4 Monoselective Halodefluorination
5 Cascade Reactions Involving Halodefluorination
6 Summary and Outlook
Key words
halodefluorination - halogen exchange - Finkelstein reaction - C–F activation - fluoroalkanes
