The structure of 4-phenyl-2,6-bis(trifluoroacetyl)cyclohexanone and its dilithium salt in the crystal state, solution and gas phase

Halogenation of Fluorinated 1,3,5‐Triketones

“…Formation of 6a can be explained via a partial hydrolysis of 7a. Indeed, for the MeOH and propan-1-ol adducts 7a,b obtained in situ (established by 19 F-NMR spectrosA C H T U N G T R E N N U N G copy), the complete conversion into 6a was observed on exposure of the reaction mixture to atmospheric moisture (Scheme 2, Entries 17 and 18). It is worthy of mention that halogenation of cyclohexanones 1b,c in the presence of EtOH also allowed to trap the intermediary cis-a,a'-dihalogenated compounds 4 (Scheme 2, Entries 19 and 20).…”

“…2 ) The tendency of the highly halogenated ketones to add H 2 O is well known [13], with hexafluoro- distilled from P 2 O 5 and in CHCl 3 of commercial quality (Scheme 2, Entries 10 and 11), only cis-4a was detected in the reaction mixture by 19 F-NMR spectroscopy (d(F) À 69.7). Its transformation to 6a took place in both experiments only on the final evaporation of the reaction mixture under air.…”

“…The behavior of cis-4a in CHCl 3 solution acidified by 12% hydrochloric acid supports this last assumption. An equilibrium cis-4a G H 6a was detected by 19 F-NMR spectroscopy (mol-ratio 64 : 36, respectively, after 16 h at room temperature). On the other hand, as mentioned, 3 and cis-4a did not add H 2 O in a pure state.…”

“…Compounds 1 were prepared by a double condensation of the corresponding ketone and ethyl trifluoroacetate with LiH as a base (1a and 1d: in MeOCH 2 -CH 2 OMe as a solvent, according to [7] and [18 a], resp. ; 1b [18] and 1c: in THF as a solvent, according to [19]).…”

“…Attempts to convert 1a with elemental Br 2 furnished only complex mixtures of several products -whatever molar amount of Br 2 was used (Entry 3). Tetrabrominated triketone 3 could be detected by 19 F-NMR spectroscopy in any case (d(F) À 67.2), but its yields were not satisfactory. By contrast, a,a'-dibromination of 1b could be performed successfully with 2 equiv.…”