## 2 Experimental Section
### General Procedure for the Preparation of Selectively Fluorinated Ketones [10,13]  
A 100 mL round bottom flask equipped with a magnetic stirrer is charged with 40 mL CH\({}_{3}\)CN and the ketone (1 eq: 1-10 mmol). Then, Selectfluor(r) (1-3 eq (3-30 mmol)) dissolved in 30 mL CH\({}_{3}\)CN is added slowly while stirring. The solution is either allowed to stir at room temperature or refluxed as required. Times range from 10-30 h. The resulting solution is evaporated to dryness under reduced pressure and the solid residue taken up in distilled water. This solution is extracted with CH\({}_{2}\)Cl\({}_{2}\), and the organic layer dried over Na\({}_{2}\)SO\({}_{4}\). The solvent is evaporated under reduced pressure and the crude fluorinated ketone purified by radial chromatography. 2-fluoro-1,3-indanedione **(1b)**. This compound was obtained in 60% yield as pale yellow crystals (EtOH), m.p. 97-99 \({}^{\circ}\)C lit [14] (m.p. 96-98 \({}^{\circ}\)C). NMR: \({}^{1}\)H: \(\delta\) 5.4 (d, \({}^{1}\)J\({}_{\text{H-F}}\) = 51.0 Hz, 1H), 7.65-8.22 (m, 4H). \({}^{13}\)C: \(\delta\) 90.1 (d, \({}^{1}\)J\({}_{\text{C-F}}\) = 211.2 Hz, CF), 125.3, 138.9, 141.9, 193.5 (d, \({}^{2}\)J\({}_{\text{C-F}}\) = 24.0 Hz, C-CF). \({}^{19}\)F: \(\delta\) \(-\)207.3 (d, \({}^{1}\)J\({}_{\text{F-H}}\) = 51.1 Hz, 1F). HRMS (ESI+) Calc. for C\({}_{9}\)H\({}_{5}\)FO\({}_{2}\): 164.02740. Found: 164.027580. 2,2-difluoro-1,3-indanedione **(1c)**. This compound was obtained in 60% yield from fluorination of **1b** as described in the general procedure above as yellowish-brown crystals (EtOH), m.p. 116-117 \({}^{\circ}\)C, lit [15] (m.p. 117-118 \({}^{\circ}\)C). NMR: \({}^{1}\)H: \(\delta\) 8.0-8.15 (m, 4H). \({}^{13}\)C: \(\delta\) 104.0 (t, \({}^{1}\)J\({}_{\text{C-F}}\) = 264 Hz, CF\({}_{2}\)), 128.8, 138.2, 139.3 (t, \({}^{3}\)J\({}_{\text{C-F}}\) = 4.3 Hz), 185.8(t, \({}^{2}\)J\({}_{\text{C-F}}\) = 24.0 Hz, C-CF\({}_{2}\)). \({}^{19}\)F: \(\delta\) \(-\)125.9 (s, 2F). [\(\Delta\)1,2'-Biindan]-1',3,3'-trione (**1d**). This compound was obtained in 72% yield as orange crystals (EtOH), m.p. 207-209 \({}^{\circ}\)C, lit [16] (m.p. 205-208 \({}^{\circ}\)C). NMR: \({}^{1}\)H: \(\delta\) 4.17 (s, 2H), 7.74-8.04 (m, 8H), 9.50 (d, J = 7.8 Hz, 1H). \({}^{13}\)C: \(\delta\) 43.4, 123.0, 123.4, 123.5, 125.8, 131.7, 134.2, 135.3, 135.4, 140.4, 141.2, 141.6, 145.9, 155.4, 189.5, 191.0, 201.2. [\(\Delta\)1,2'-Biindan]-2-fluoro-1',3,3'-trione (**1e**). This compound was obtained was obtained in 85% yield from fluorination of **1d** as described in the general procedure above as orange crystals (EtOH), m.p. 165-168 \({}^{\circ}\)C (dec). NMR: \({}^{1}\)H: \(\delta\) 6.45 (d, \({}^{1}\)J\({}_{\text{H-F}}\) = 46.1 Hz, 1H), 7.75-8.20 (m, 7H), 9.50 (d, J = 7.7 Hz, 1H). \({}^{13}\)C: \(\delta\) 70.8 (d, \({}^{1}\)J\({}_{\text{C-F}}\) = 194 Hz, CF), 125.4, 126.6, 129.3, 130.1, 132.0, 137.7, 138.5, 166.3, 189.3, 191.2, 204.1 (d, \({}^{2}\)J\({}_{\text{C-F}}\) = 24 Hz, C-CF). \({}^{19}\)F: \(\delta\) \(-\)182.4 (d, \({}^{1}\)J\({}_{\text{F-H}}\) = 46.0 Hz, 1F). Analysis calcd for C\({}_{18}\)H\({}_{9}\)FO\({}_{3}\): C, 73.97, H, 3.10. Found: C, 74.06, H, 3.21. 2-fluoro-2-(2'-fluoro-3'-oxoinendenyl)-1,3-indanedione **(1f**). This compound was obtained in 92% yield from fluorination of **1e** as described in the general procedure above as yellow crystals (EtOH), m.p. 126-129 \({}^{\circ}\)C. NMR: \({}^{1}\)H: 7.8-8.25 (7H, m), 9.53 (1H, d, J = 6.9 Hz). \({}^{13}\)C: \(\delta\) 89.9, 125.1, 126.3, 129.5, 130.0, 132.2, 137.1, 138.0 (d, \({}^{1}\)J\({}_{\text{C-F}}\) = 254 Hz, CF), 166.1, 185.9, 189.1. \({}^{19}\)F: \(\delta\) \(-\)137.3 (s, 1F),\(-\)176.7 (s, 1F). HRMS (ESI+) calcd for C\({}_{18}\)H\({}_{8}\)F\({}_{2}\)O\({}_{3}\): 310.04415. Found: 310.04415. 1-trifluoroacetyl-2-indanone (**2b**). This compound was obtained in 52% yield as a brown oil.