Conversion of 1,4-diketones into para -disubstituted benzenes

摘要

Reaction of acetylides with aldehydes to form but-2-yne-1,4-diols, followed by triple bond reduction and oxidation of the hydroxyl groups, gives 1,4-diketones; these react with vinyllithium, and the resulting diols undergo ring-closing metathesis to form 2-cyclohexene-1,4-diols. Dehydration, usually by acid treatment, then gives benzenes carrying substituents in a 1,4 relationship. Use of substituted vinyllithiums provides further substitution on the final benzene rings. The method can be applied to the synthesis of C5-aryl carbohydrates.