Organic Compounds Containing Fluorine

5-Fluorocyclopentadiene: synthesis and utility

“…Reaction of Compound 2 with 4-Phenyl-1,2-triazoline-3,5-dione &-(a) Compound 7 (0.41 gl2.7 mmol g-' F + , 1.1 mmol) was added slowly over 10 min to a stirred solution of cyclo-pentadienylthallium (0.27 g, 1 mmol) in acetonitrile. After a further 15 min the reaction mixture was filtered through a Celite pad (ether eluent) onto compound 8 (0.18 g, 1 mmol), and the reaction mixture was stirred for a further 4 h. The solvent was then removed under reduced pressure and the residue chromatographed over silica gel to yield 10-fluorotricyclo-C5.2.1.0 2*6]deca-3,8-dien-5-one 10 (0.032 g, 0.2 mmol, 39%) as a slightly yellow liquid; A,,,/nm (CC1,H) 240, v(KBr)/cm-' 2929, 1698, 1344, 1251 and 1034; SH(250 MHz, CDCl,) 7 (b) A slurry of cyclopentadienylthallium (0.27 g, 1 mmol) and compound 7 (0.41 g/2.7 mmol g-' F+, 1.1 mmol) in acetonitrile (10 cm3) was added to a stirred solution of compound 8 (0.34 g, 1.9 mmol) in ether (20 cm3). After 1 h the mixture was filtered through a Celite pad and the pad washed with ether.…”