Oxocarbons and related compounds; Part 18. The reaction of perchlorocyclobutenone with pyridines: A novel synthesis of 4H-4-quinolizinones

Article abstract of DOI:10.1055/s-1992-26281

Heating of tetrachlorocyclobutenone (5) with the pyridines 6a-i followed by treatment with water affords 1,3-dichloro-2-hydroxy-4H-4-quinolizinones 7a, b, g-h and 1,3-dichloro-2-hydroxy-4-oxo-4H-quinolizinecarboxylates 7c-f. The reaction pathway has been secured by trapping 1,2,3-trichloro-8-(1,1-dimethylethyl)-4H-4-quinolizinone (11b) and by its successive conversion to 7b on heating with water.