5-Phenyl-3-pentanone

Problem 17.10 (a) Use carbanion-enolate alkylations to synthesize (i) 2-ethylbutanenitrile, (ii) 3-phenyl-2-pentanone, (iii) 2-benzylcyclopentanone. (6) Why can the unsymmetrical ketone in part (ii) be alkylated in good yield "4... 

The shift reagent Eu(facam)3 has also been successfully used to determine the enantiomeric composition of a sample of D,L-3-methyl-3-phenyl-2-pentanone. The chiral shift reagent caused separation of some of the peaks arising from the two enantiomers. The spectrum of D,L-3-methyl-3-phenyl-2-pentanone in the presence of added Eu(facam)3 is shown in Fig. 10.22. The acyl methyl protons are well resolved as seen on the left side of the figure and their relative areas may be integrated. The optical purity of this sample... 

Fig. 10.22. Spectrum of a CCI4 solution of D,L-3-methyl-3-phenyl-2-pentanone in 0.5 M Eu(facam)3 [54],...

Consider the reduction of (/ )-3-phenyl-2-pentanone by sodium borohydride. After the reduction is complete, the mixture is separated by chromatography into two fractions. These fractions contain isomeric compounds, and each isomer is optically active. What are these two isomers and what is the stereoisomeric relationship between them ... 

Describe differences in the IR and proton NMR that will allow you to distinguish 3-phenyl-1-pentanal and 3-phenyl-2-pentanone. 

Thus, a short-range strategy for the synthesis of 4-hydroxy-l-phenyl-pentanone-2 (I) will lead to the two carbonyl compounds methyl benzyl ketone and acetaldehyde as synthesis precursors (Figure 1). Having reached this conclusion it is absolutely necessary to consider whether those two precursors will react by the anticipated aldol condensation to the target compound (I). A closer inspection based on insight into chemical reactivity has to decide that this reaction will not proceed unequivocally to the desired product (I). Rather, a mixture of compounds will be obtained including the... 

FIGURE 13 26 NMR spectra of 1 phenyl 1 pentanone (a) Normal spectrum (b) DEPT spec trum recorded using a pulse sequence in which CH3 and CH carbons appear as positive peaks CH2 carbons as negative peaks and carbons without any attached hydrogens are nulled... 

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 mixture of 7.3 parts l-chloro-4,4-di-(4-fluorophenyl)-butane, 5.1 parts l-phenyl-4-oxo-l,3,8-triaza-spiro(4,5)-decane, 4 parts sodium carbonate, a few crystals of potassium iodide in 200 parts 4-methyl-2-pentanone is stirred and refluxed for 60 hours. After cooling the reaction mixture is treated with water. The organic layer is separated, dried, filtered and evaporated. The solid residue is recrystallized from 80 parts 4-methyl-2-pentanone, yielding l-phenyl-4-oxo-8-[4,4-di-(4-fluorophenyl)-] butyl-1,3,8-triaza-spiro(4,5)decane, melting point 187.5° to 190°C. 

B) A mixture of 2.4 parts of 1 acetyl-4-(4-hydroxyphenyl)piperazine, 0.4 part of sodium hydride dispersion 78% 75 parts of dimethylsulfoxide and 22.5 parts of benzene is stirred for one hour at 40°C. Then there are added 4.2 parts of cis-2-(2,4-dichlorophenyl)-2-(1 H-imidazol-1 -ylmethyl)-1,3-dioxolan-4-ylmethyl methane sulfonate and stirring is continued overnight at 100°C. The reaction mixture Is cooled and diluted with water. The product is extracted with 1,1 -oxybisethane. The extract is dried, filtered and evaporated. The residue Is crystallized from 4-methyl-2-pentanone. The product is filtered off and dried, yielding 3.2 parts (59%) of cis-1-acetyl-4-[2-(2,4-dichlorophenyl)-2-(1 H-imidazol-1-ylmethyl)-13-di-oxolan-4-ylmethoxy] phenyl] piperazine MP 146°C. 

The aldol reaction of 2,2-dimethyl-3-pentanone, which is mediated by chiral lithium amide bases, is another route for the formation of nonracemic aldols. Indeed, (lS,2S)-l-hydroxy-2,4,4-trimethyl-l-phenyl-3-pentanone (21) is obtained in 68% ee, if the chiral lithiated amide (/ )-A-isopropyl-n-lithio-2-methoxy-l-phenylethanamine is used in order to chelate the (Z)-lithium cnolate, and which thus promotes the addition to benzaldehyde in an enantioselective manner. No anti-adduct is formed25. 

Metalation ofa-sulfinyl dimethylhydrazones with terf-butylmagnesium bromide, butyllithium or lithium diisopropylamide, and reaction of the generated azaenolates with aldehydes, provides aldol adducts (e.g., 6) as mixtures of diastereomers. Reductive desulfurization leads to fi-hydroxy dimethylhydrazones (e.g., 7) which are cleaved to the desired /(-hydroxy ketones in 25% overall yield10 u. The enantiomeric excesses are about 50%, except for (- )-3-hydroxy-4-methyl-1-phenyl-1-pentanone (8) which was obtained in 88% ee. 

CN ( )-5-methoxy-1 -[4-(trifluoromethyl)phenyl]-1 -pentanone 0-(2-aminoethyl)oxime hydrogen maleate... 

The first element of stereocontrol in aldol addition reactions of ketone enolates is the enolate structure. Most enolates can exist as two stereoisomers. In Section 1.1.2, we discussed the factors that influence enolate composition. The enolate formed from 2,2-dimethyl-3-pentanone under kinetically controlled conditions is the Z-isomer.5 When it reacts with benzaldehyde only the syn aldol is formed.4 The product stereochemistry is correctly predicted if the TS has a conformation with the phenyl substituent in an equatorial position. 

This method, an adaptation of a previously described procedure,2- 8-4 has been used with a variety of amino acids and anhydrides to give the following products 1-phenyl-1-propionamidO-2-butanone (75%) 6 acetamidoacetylacetone (60%) 6 N-methyl-acetamidoacetone 6 l-phenyl-2-acetamido-3-butanone (79%) 7 l-phenyl-2-propionamido-3-pentanone (41%) 7 l-phenyl-2-butyr-amido-3-hexanone (27%) 7 a-benzamidopropiophenone (42%) 7 a-benzamido-/3-phenylpropiophenone (44%) 7 1 -phenyl-1 -aceta-midoacetone (72-90%) 8-91-phenyl-1-benzamidoacetone (65%) 8 l-phenyl-2-benzamido-3-butanone (78%) 8 3-benzamido-2-buta-none (65-88%) 8 and 3-acetamido-5-methyl-2-hexanone (73%).10... 

AI3-00040, see Cyclohexanol AI3-00041, see Cyclohexanone AI3-00045, see Diacetone alcohol AI3-00046, see Isophorone AI3-00050, see 1,4-Dichlorobenzene AI3-00052, see Trichloroethylene AI3-00053, see 1,2-Dichlorobenzene AI3-00054, see Acrylonitrile AI3-00072, see Hydroquinone AI3-00075, see p-Chloro-rrr-cresol AI3-00078, see 2,4-Dichlorophenol AI3-00085, see 1-Naphthylamine AI3-00100, see Nitroethane AI3-00105, see Anthracene AI3-00109, see 2-Nitropropane AI3-00111, see Nitromethane AI3-00118, see ferf-Butylbenzene AI3-00119, see Butylbenzene AI3-00121, see sec-Butylbenzene AI3-00124, see 4-Aminobiphenyl AI3-00128, see Acenaphthene AI3-00134, see Pentachlorophenol AI3-00137, see 2-Methylphenol AI3-00140, see Benzidine AI3-00142, see 2,4,6-Trichlorophenol AI3-00150, see 4-Methylphenol AI3-00154, see 4,6-Dinitro-o-cresol AI3-00262, see Dimethyl phthalate AI3-00278, see Naphthalene AI3-00283, see Di-rj-butyl phthalate AI3-00327, see Acetonitrile AI3-00329, see Diethyl phthalate AI3-00399, see Tributyl phosphate AI3-00404, see Ethyl acetate AI3-00405, see 1-Butanol AI3-00406, see Butyl acetate AI3-00407, see Ethyl formate AI3-00408, see Methyl formate AI3-00409, see Methanol AI3-00520, see Tri-ocresyl phosphate AI3-00576, see Isoamyl acetate AI3-00633, see Hexachloroethane AI3-00635, see 4-Nitrobiphenyl AI3-00698, see IV-Nitrosodiphenylamine AI3-00710, see p-Phenylenediamine AI3-00749, see Phenyl ether AI3-00790, see Phenanthrene AI3-00808, see Benzene AI3-00867, see Chrysene AI3-00987, see Thiram AI3-01021, see 4-Chlorophenyl phenyl ether AI3-01055, see 1.4-Dioxane AI3-01171, see Furfuryl alcohol AI3-01229, see 4-Methyl-2-pentanone AI3-01230, see 2-Heptanone AI3-01231, see Morpholine AI3-01236, see 2-Ethoxyethanol AI3-01238, see Acetone AI3-01239, see Nitrobenzene AI3-01240, see I idine AI3-01256, see Decahydronaphthalene AI3-01288, see ferf-Butyl alcohol AI3-01445, see Bis(2-chloroethoxy)methane AI3-01501, see 2,4-Toluene diisocyanate AI3-01506, see p,p -DDT AI3-01535, see 2,4-Dinitrophenol AI3-01537, see 2-Chloronaphthalene... 

Problem 17.11 Use enamines in the following conversions (a) cyclohexanone to (i) 2-allylcyclohexanone and (ii) 2-acetylcyclohexanone, and (f>) 3-pentanone to 2-methyl-l-phenyl-3-pentanone. <... 

Pentanone Petroleum distillates Phenyl ether vapor Phenyl glycidyl ether n-Propyl acetate Propyl alcohol n-Propyl nitrate Propylene dichloride Propylene oxide Pyridine... 

The procedure reported here provides a convenient method for the a-hydroxylation of ketones which form enolates under the reaction conditions. The reaction has been applied successfully to a series of para-substituted acetophenones, 1-phenyl-1-propanone, 3-pentanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclododecanone, 2-methyl cyclohexanone, 2-norbornanone and benzalacetone. In the case of a steroidal example it was shown that a carbon-carbon double bond and a secondary hydroxyl group are not oxidized. A primary amino function, as in the case of p-aminoacetophenone, is not affected.5 Similarly, a tertiary amino ketone such as tropinone undergoes the a-hydroxy at ion reaction.5... 

Zhang, N., Wu, J.L. 1991. Scavenger effects in the radiolysis of cyclohexane 4-methyl-4-phenyl-2-pentanone system and cyclohexane tributyl phosphate system. Radiat. Phys. Chem. 38 383-388. 

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