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

Abstract

Bicyclo[3.3.1]nonane system is an important structural motif observed in a diverse natural products. Here, we report a concise synthetic route exploiting aldol condensation reactions for construction bicyclo[3.3.1]nonane ring system. Our strategy employes cyclohex-2-enones bearing another carbonyl group in side chain as key structural unit. The reaction showed good results for substrates bearing electron-donating groups in aromatic substituents. Overall, the described synthesis of bicyclo[3.3.1]nona-3,6-dien-2-ones required 2 steps and only 2 building blocks (such as Mannich base and acetoacetic ester) to access desired bicyclic system.