FLUOROCARBON DERIVATIVES OF NITROGEN .18. SYNTHESIS OF FLUORINATED INDOLIZINES THROUGH REACTIONS OF PYRIDINIUM ETHOXYCARBONYLMETHYLIDE OR PYRIDINIUM PHENACYLIDE WITH PERFLUOROPROPENE, PERFLUOROBUT-2-YNE AND 3,3,3-TRIFLUOROPROPYNE

3-Ethoxycarbonyl-2-fluoro-1-trifluoromethylindolizine (6), 3-ethoxycarbonyl-1,2-(bistrifluoromethyl)indolizine (8), 3-ethoxycarbonyl-1-trifluoromethylindolizine (10) and 3-ethoxycarbonyl-2-perfluoroheptylimidazo[1,2-a]pyridine (12) have been obtained via trapping of pyridinium ethoxycarbonylmethylide with perfluoropropene, perfluorobut-2-yne, 3,3,3-trifluoropropyne and perfluorooctanenitrile respectively. Similarly, 2-fluoro-1-trifluoromethyl-3-phenacylindolizine (7), 1,2-bis(trifluoromethyl)-3-phenacylindolizine (9), and 3-phenacyl-1-trifluoromethylindolizine (11), have been obtained via reaction of pyridinium phenacylide with perfluoropropene, perfluorobut-2-yne, and 3,3,3-trifluoropropyne respectively. Alkaline hydrolysis of (8) gave 1,2-bis(trifluoromethyl)indolizine-3-carboxylic acid (16), which was decarboxylated thermally to 1,2-bis(trifluoromethyl)indolizine (15).