94562-76-2Relevant academic research and scientific papers
Heterocyclic Compounds with Bridgehead Nitrogen Atoms. Part 10. Synthesis in the Pyrroloquinolizine Series (Cyclazinones and Cyclazinylium Salts) starting from Quinolizines
Farquhar, David,Gough, Thomas T.,Leaver, Derek,Miller, James F.,Dick, James W.,Jessep, Michael A.
, p. 2553 - 2562 (2007/10/02)
Ethyl 1-oxo-1H-pyrroloquinolizine-2-carboxylate was obtained by thermal cyclisation of diethyl quinolizin-4-ylidenemalonate and the corresponding 3-oxo-3H-1-carboxylate by reaction of 3-hydroxyquinolizinylium bromide with sodium carbonate and ethyl propynoate in boiling nitrobenzene.These isomeric esters were hydrolysed and decarboxylated to give 1H- and 3H-pyrroloquinolizin-1- and -3-ones and were converted into various pyrroloquinolizinylium salts, including the parent compound.The n.m.r. spectra and chemical properties of the pyrrolo quinolizinylium ion are consistent, for the most part, with a structure in which the 1,2-bond is part of the aromatic system.Nucleophilic attack on this ion occurs at C-3 and, to a lesser extent, at C-5.Among the compounds obtained by such reactions was 5H-pyrroloquinolizin-5-one, thus leaving the corresponding 4-oxo-4H-compound as the only member of this isomeric series that remains unknown.
