9-Alkenylcarbazoles. 6. Synthesis and structure of cis-9-propenylcarbazoles

A number of cis-9-propenylcarbazoles were synthesized in good yields by isomerization of 9-allylcarbazoles by the action of tert-BuOK in dimethyl sulfoxide. It was established that cis-9-propenylcarbazole is less thermodynamically stable than its trans isomer. It was shown by¹³C NMR, UV, and IR spectroscopy that the effect of p-π conjugation in cis-9-propenylcarbazole decreases as compared with the trans isomer as a result of the noncoplanarity of the C=C bond and the carbazole ring. See 1] for communication 5. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 340–343, March, 1980.