SYNTHESIS OF 2-HETEROBICYCLO[3.2.1]OCTANES AND THE CORRESPONDING MONOENES AND DIENES

Synthesis of the theoretically interesting 2-heterobicyclo[3.2.1.]octa-3,6-dienes and their dihydro-and tetrahydro-derivatives has been achieved in the oxygen, nitrogen and sulphur series. The parent compound of the nitrogen series appears to exist as 2-azabicyclo[3.2.1]octa-2,6-diene rather than as the enamine (3, R=H). The Cope rearrangement equilibrium (2, X=NR)⇌(3) lies more to the side of the diene 3 when nitrogen is substituted with an electron withdrawing group than when an alkyl substituent is present. These effects seem to suggest no special bishomoconjugative stabilisation in the dienes 3. © 1979.