2- Butanone, 1,1,1 -trifluoro-4-

Compare electrostatic potential maps of enolates derived from 2-butanone, 4,4-dimethyl-2-pentanone, 4,4,4-trifluoro-2-butanone and l-phenyl-2-propanone with those of acetone. Which substituents cause significant changes in the electronic structure of these enolates and what are the nature of these changes Justify your answers by making drawings of any important resonance contributors. 

A freshly prepared 1 -M solution of methylmagnesium chloride in tetrahydrofuran (10 mL, 10 mmol) is added dropwise (30 min), under nitrogen, to a stirred solution of freshly distilled (5)-(-)-2-methoxy-2-phenyl-3,3,3-trifluoropropionyl chloride (2.52 g, 10 mmol) and tris(acetylacetonato)iron (0.11 g, 0.3 mmol) in 100 mL of dry tetrahydrofuran at room temperature. After complete addition, the stirring is continued for 10 min at the same temperature. Then, the reaction is quenched with aqueous hydrochloric acid (10%) and extracted with several portions of diethyl ether. The combined ether extracts are washed with aq. sodium bicarbonate and water, and they are dried over sodium sulfate. The solvent is removed and the residue is distilled to give (/ )-(-)-3-methoxy-3-phenyl-4,4,4-trifluoro-2-butanone bp 110-112 °C (15 mbar) [a]o -170.6 (c 3.5, CHCI3) 2.1 g (90%). 

There is no noticeable four-bond coupling between the CF3 fluorines and the CH2 group of l,l,l-trifluoro-2-butanone, as can be seen in the H spectrum of this compound given in Fig. 5.7. 

FLUOROPHENYL)-4-(4-HYDROXY-4-(3-(TRIFLUORO-METHYL)PHENYL)-l-PIPERIDINYL)-l-BUTANONE MCN-JR-2498 PSICOPERIDOL-R PSYCHOPERIDOL R-2498 TRIFLUPERIDOLO (ITALIAN) TRIPERIDOL... 

These findings are not surprising since the alpha carbon atoms of these diazo compounds carry an aromatic ring. However, it has been observed recently by Dahn et al. [210] that solvent isotope effects are larger than 1 in the acid catalyzed hydrolyses of various secondary diazoketones (such as 3-diazo-2-butanone), ethyl a-diazopropionate, and l,l,l-trifluoro-2-diazopropane. Similar results have been obtained by Jugelt and Berseck... 

Trifluoro-2-oxopropanal l-(dimethylhydrazone) 1447 is a synthetic equivalent of trifluoropyruvaldehyde. Like its 1,2-dicarbonyl counterpart, compound 1447 participates in the condensation reaction with aldehydes and ammonium acetate to afford 4-trifluoromethylimidazoles 1448 in 42-72% yield <2003H(60)1185>. 1,1,1-Trifluoro-2,3-alkanediones 1449, also 1,2-dicarbonyl equivalents, condense with aldehydes and aqueous ammonia to yield 4-(trifluoromethyl)imidazoles 1450 <2001JHC773>. 3-(Dimethylhydrazono)-l,l,l,4,4,4-hexafluoro-2-butanone... 

Cyclization to the butanone (5) was effected by stirring 6.28 g. of the dinitro-benzenesulfonate (4) for 5 days at 45° in a mixture of 4.1 g. of sodium trifluoro-acetate and 50 g. of trifluoroacetic acid (if sodium trifluoroacetate is omitted, higher-boiling products are formed and the yield of 2-methylcyclobutanone is much lower). 

Butane, 2,3-0-isopropylidene-2,3-dihydroxy-l,4-bis(diphenylphosphino)-rhodium complexes asymmetric hydrogenation, 251 Butane-2,4-dione, l,l,l-trifluoro-4-(2-thenoyl)-in uranium ore processing, 910 2-Butanone, 4-alkoxy-carbonylation... 

The effect of solvent structure on the regioselectivity can, apparently, be quite strong as is illustrated by the reaction of butanone vith p-trifluoro-benzaldehyde (Scheme 4.38, Eqs. (2) and (3)). 

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