Synthesis of 6-Substituted 7H-Pyridocarbazoles

Article abstract of DOI:10.1021/jo00274a024

Condensation of N-(phenylsulfonyl)-2-methoxalylindole and its 5-methoxy analogue with a modified Wittig reagent prepared from diphenyl(4-pyridylmethyl)phosphine oxide furnished the olefins 16 and 17, respectively.Oxidative photocyclization furnished the 6-carbomethoxy-7H-pyrido<4,3-c>carbazoles 18 and 24.Reduction with lithium aluminium hydride gave the carbinols 19 and 23, which when treated with methyl isocyanate gave the corresponding N-methylcarbamates 20 and 26, which are potential antitumor agents.Manganese dioxide oxidation of 19 and 25 furnished the aldehydes 21 and 27.Treatment with methylenetriphenylphosphorane gave olefins 22 and 28, which upon catalytic reduction afforded the 6-ethyl-7H-pyrido<4,3-c>carbazoles 23 and the known 29.