## 3 Results and Discussion  
### Synthesis  
Compounds **1a-5a** are commercially available and were used without further purification. Compounds **1b** and **1c** have been previously described, but were prepared according to a different method [14, 15]. Compound **1d** is known and was synthesized via a previously described method [12, 16]. The remaining compounds were prepared using a modified Claisen condensation or direct fluorination with Selectfluor(r)[10, 12, 13, 18, 19]. See Scheme 1. Recent work by our group showed that regioselective monofluorination and geminal difluorination of acyclic \(\beta\)-diketones could be effected with Selectfluor(r) under mild conditions without the necessity of specialized glassware or safety precautions [10, 14, 15]. The current synthetic investigation sought to take advantage of this earlier work by probing Selectfluor(r)'s efficiency and effectiveness in the mono- and difluorination of 1,3-indanedione and bindone. Our efforts revealed some unexpected findings. The monofluorination of **1a** proceeded with little difficulty to give 2-fluoro-1,3-indanedione (**1b**) in the diketonic form (as evidenced by a doublet signal (J\({}_{\text{F-H}}\) = 51.1 Hz) in the \({}^{19}\)F NMR at \(-\)207.3 ppm), albeit in slightly lower yield compared to fluorination achieved with 5% F\({}_{2}\) in N\({}_{2}\)[10]. Diketone **1b** was also successfully fluorinated (as evidenced by a singlet signal in the \({}^{19}\)F NMR at \(-\)125.9 ppm), delivering the geminally difluorinated product **1c** in good overall yield. We then examined whether bindone, the aldol self-condensation product of 1,3-indanedione, would react similarly to treatment with Selectfluor(r). As expected, monofluorination was achieved in high yield to give **1e** as an enantiomeric triketone pair (\({}^{19}\)F NMR: \(-\)182.4 ppm, J\({}_{\text{F-H}}\) = 46.0 Hz), but the site of fluorination was the \(\alpha\)-carbon adjacent to the isolated ketone rather than fluorination between the 1,3-diketone residue. Subsequent fluorination of **1e** likewise yielded interesting results. Particularly noteworthy were the fluorination regioselectivity and alkene rearrangement observed during the formation of triketone **1f**. We expected an outcome similar to the fluorination of **1b**, but the occurrence of two distinct signals in the \({}^{19}\)F NMR at \(-\)137.3 ppm and \(-\)176.7 ppm ruled out geminal difluorination. Evidently, the alkene in **1e** retains sufficient nucleophilic nature to permit electrophilic fluorination between the \(\beta\)-dicarbonyl residue. This addition, coupled with a concomitant E1-like elimination leads to **1f**, rather than formation of [\(\Delta\)1,2'-Bihdan]-2,2-difluoro-1',3,3'-trione, shown in Scheme 1. While preparing **2b** and **2c**, the previously undescribed one-pot, twin trifluoroacetylation of 2-indanone gave the dual exocyclic enol **2c** in moderate yield (confirmed by the presence of a single \({}^{19}\)F NMR resonance at \(-\)68.5 ppm) and no **2c'**, Figure 2. In this case, the ethoxide base present following the condensation apparently deprotonates the unsubstituted benzylic \(\alpha\)-hydrogen (H\({}_{3}\)) rather than the more acidic \(\alpha\)-hydrogen H\({}_{1}\). There are several possible explanations for the formation of **2c** and the failure to obtain **2c'**. The most plausible scenario involves initial formation of **2c'**. Given the basic reaction conditions, however, we surmise that upon attachment of the second COCF\({}_{3}\) group, **2c'** may undergo nucleophilic acyl substitution by ethoxide, reverting **2c'** back to enolate **A**. A second possibility for the failure to obtain  
**2c'** may be larger steric demands in the transition state leading to enolate **A** formation relative to that leading to enolate **B**. Finally, a base-promoted tautomerization from enolate **A** to enolate **B** could occur before formation of **2c'**, ultimately leading to **2c**.