Spirans XVIII . gem-Dialkyl and spirotetrahydrocarbazoles

The reactions of 4,4-dialkylcyclohexanones, spiro4.5]decan-8-one and various spiro5.5]-undecanones with phenylhydrazines to produce corresponding 3,3-dialkyltetrahydro and spiro (cycloalkyl 1,n′)-1′,2′,3′,4′-tetrahydrocarbazoles (n = 1, 2 or 3) by the Fischer indole synthesis were examined. Structural assignment of the one isomeric product derived from spiro5.5]-undecan-2-one was obtained on the basis of pmr spectra.