The synthesis of substituted bicyclo[3.2.1]octa‐2,6‐dienes

Abstract Bicyclo[3.2.1]octa‐2,6‐diene‐ ax ‐ and ‐ eq ‐4‐carboxylic acids (IIIa) have been prepared via Knoevenagel condensation of bicyclo[3.1.0]hex‐2‐ene‐6‐ endo ‐carbaldehyde (Ia). Synthesis and properties are reported of endo ‐4‐ t ‐butoxy‐bicyclo[3.1.0]hex‐2‐ene‐6‐ endo ‐carbaldehyde (Ib). This aldehyde has been converted to endo ‐8‐ t ‐butoxybicyclo[3.2.1]octa‐2,6‐diene (IIIb) and to endo ‐8‐ t ‐butoxybicyclo[3.2.1]octa‐2,6‐diene‐ ax ‐ and ‐ eq ‐4‐carboxylic acids (IIIc) respectively via Wittig methylenation and Knoevenagel condensation.