Novel 1,4-Homofragmentation via an α-Lactone

Conversion of an α,α-dichloroester to the corresponding
α-keto acid was unexpectedly complicated by a novel 1,4-homofragmentation. Investigation of the kinetics of this
reaction revealed a mechanism involving an α-lactone
intermediate, which can lead to both the desired α-keto acid
and the 1,4-homofragmentation, with the product distribution
being dependent upon reaction conditions. This information
allowed development of a process that affords the α-keto
acid exclusively and should be generally applicable to the
preparation of α-keto acids from α,α-dichloroesters or acids.