Synthesis of 4,6-Diarylbicyclo[3.3.1]nona-3,6-dien-2-ones

Bicyclo[3.3.1]nonane system is an important structural motif in many natural compounds. This article describes a short synthetic route to the bicyclo[3.3.1]nonane system via aldol condensation. The proposed strategy is based on the use of cyclohex-2-en-1-ones containing an additional carbonyl group in the side chain as a key precursor. The approach showed good results for compounds with electron-donating groups in aromatic substituents. An obvious advantage of such synthesis of bicyclo[3.3.1]nona-3,6-dien-2-ones is that it involves two steps and requires only two building blocks, namely a Mannich base and ethyl acetoacetate.