Access to 2,4,6-triazatetracyclo[5.3.2.02,6.08,10]dodecenes by the hetero-Diels–Alder reaction between cycloheptatrienes and azodicarboxylic acid imide

Novel 2,4,6-triazatetracyclo[5.3.2.0^2,6.0^8,10]dodec-11-ene-3,5-diones were prepared in high yields (86–96%) via the hetero-Diels–Alder reaction of azodicarboxylic acid N-phenylimide with 7-substituted cycloheptatrienes. The adducts are formed exclusively via the endo-addition of the azo dienophile to bicyclo[4.1.0]hepta-2,4-diene, the norcaradiene tautomer. The cyclopropane ring in the adduct is syn-oriented relative to the double bond and contains an exo-directed substituent.