The peculiar behaviour of the trifluoromethyl substituent in S RN1 processes

Abstract

Reaction of the enolate of 3,3-dimethylbutan-2-one with α,α,α-trifluoro-o-iodotoluene in a SRN1 process does not yield the expected substitution product, but a more complex molecule deriving from It. An accurate n.m.r. analysis of the products, along with other evidence, indicates a mechanism for this rearrangement, where an interaction of the trifluoromethyl group with the adjacent enolate moiety occurs, once the ‘normal’SRN1 substitution product has formed. The peculiar effect of the CF3 substituent is not only confined to the ortho position. Even α,α,α-trifluoro-p-iodotoluene shows unusual behaviour and affords a rearranged product. A mechanistic explanation is offered, where some of the key steps are similar to those involved in the case of the ortho isomer.