Complex examples of the Dowd–Beckwith rearrangement: a free radical route to 2-oxabicyclo 〚3.3.0〛octan-3,6-diones

Abstract

The synthesis of 8-iodooxabicyclo〚3.2.1〛octanes from substituted benzoic acids via a reductive alkylation–halolactonization sequence is described. These iodolactones were converted to 2-oxabicyclo〚3.3.0〛octane derivatives upon treatment with either allyltri-n-butylstannane or tri-n-butylstannane via a process that involves a Dowd–Beckwith rearrangement. The scope and limitations of this process are discussed.