Synthesis of pyrimido annelatedcarbazoles and 2-methyl-6-oxo-bisindolo[1,2-b :5,4-b' ] cyclohexanones using 2-hydroxymethylene-1-oxo-1,2,3,4-tetrahydrocarbazoles

Abstract

Tr eatment of 2-hydro xyme thylene-1-oxo-1, 2,3, 4- tetrahydrocarbazoles 1a-d with guanidine nitrate affords 2-amino- 4-hydroxy-1,4,5,6-tetrahydropyrimido[4,5- ]carbazoles 2a-d. In anothe r re ac tion, 2-hydro xyme thylene-1-oxo-1, 2,3, 4- tetrahydroc arbazoles 1a-d are treated with diazotized -toluidine under Japp-Klingemann conditions to furnish the respec ve 4'-methyl-1-oxo-2-phenylhydrazono-1,2,3,4-tetrahydrocarbazoles 3a-d, which upon cyclisation using Kent’s reagent (CH₃COOH : HCl, 4:1) yield the corresponding 6,12-dihydro-2-methy xobisindolo[ 1,2- :5,4-b' ]cyclohexanones 5a-d.