Synthesis of Dibenzoquinolizines - A New Entry to Protoberberines

Article abstract of DOI:10.1007/BF00811549

A novel synthesis to prepare dibenzo-8-quinolizinones 8 is reported using the intramolecular cyclisation of the benzylated Reissert compounds 6 for the key step.Methylation of 8 by methyllithium gives partial deoxygenated coralynes 10 which in turn can be reduced by NaBH4 yielding the 8-methyltetrahydro-protoberberines 11.The structures are assigned by NMR-spectroscopy. Keywords.Reissert compounds; Intramolecular cyclisation; Dibenzo-8-quinolizinones; Deoxygenated coralynes; 8-Methyltetrahydro-protoberberines.