Syntezy oliwacyny

Olivacine (1,5-methyl-6H-pyrido[4,3-b]carbazole) is an isomer of ellipticine (5,11-dimethyl-6H-pyrido[4,3-b] carbazole). Both of these heterocyclic compounds are carbazole derivatives, which exhibit broad spectrum of biological activity [1], especially as antineoplastic agents [2–9]. These four-ring heterocycles can be isolated from natural sources [10–16], or prepared synthetically. Chemical literature described more than 20 method of synthesis of olivacine [2, 17–34]. In this paper we described five selected syntheses of this alkaloid. In the first one this compound can be obtained during a multistep synthesis starting from 1-benzenesulfonyl-2-lithioindole [35]. A shorter method to get olivacine was the condensation of indole with an ethylene ketal [35]. Third synthesis starts from obtaining benzenosulfonyloindol from indole [37]. Another way starts from the synthesis of 1-(tert-butoxy)carbonyloindol [38]. Fifth method to get olivacine is the synthesis from the 1H-indole -2-carboxylate [39].