1 -Phenyl-1 -butanone

The synthesis starts by condensation of readily available optically active (R)-(+)-alpha-methylbenzylamine with 4-phenyl-2-butanone to form an imine which is itself reduced by hy-drogenolysis (Raney nickel) to give a 9 1 mixture of the (R,R)-amine and the (R,S)-amine (4). 

Phenyl-l,3-butanedione, b63 4-Phenyl-2-butanone, b77a Phenyl cellosolve, p72 Phenyl chloride, c47 Phenylcyclohexane, c376... 

Recently, we adopted the same system for the reduction of 4-phenyl-2-butanone to (S)-4-phenyl-2-butanol using the NADH-dependent horse liver alcohol dehydrogenase (HLADH) and S-ADH from Rhodococcus sp [68] with high enantioselectivity (Fig. 17) [69]. As mediator, we applied the low-molecular... 

One approach that avoids the release of potent electrophiles into the general cellular milieu is use of the quiescent affinity label.1131 These evolved from the classic (non-quiescent ) affinity labels such as L-l-chloro-3-tosylamido-4-phenyl-2-butanone (Fig. 7a)... 

The results of the interpretation of the gas phase IR and low-resolution mass spectra of 4-phenyl-2-butanone are given in Figure 4. This compound, with a molecular weight of 148, is t3rpical of the size and complexity of compounds which our program handles well. The IR spectrum was taken from the EPA gas-phase IR library, and the mass spectrum from the Registry of Mass Spectral Data.(35)... 

Figure 4. Substructures reported for 4-phenyl-2-butanone at > 10% confidence, for three runs of the interpreter using different data sets.

A modified rare earth catalyst (30) which is based on a polystyrene backbone as depicted in Scheme 4.15 can be applied even in neat water. It is attached via a hydrophobic oligomeric linker which creates a nonpolar reaction environment and acts as a surfactant for the substrates. The reaction of 4-phenyl-2-butanone with tetraallyltin in water using 1.6 mol% of the scandium catalyst (30) afforded the corresponding homoallylalcohol in a yield of 95%. Interestingly, when using other solvents (dichloromethane, acetonitrile, benzene, ethanol, DMF) the yields decreased drastically, indicating a much higher reaction rate in water [98]. 

The stereochemistry of this reaction was also investigated (equation 42). Thus, geometrical isomers of 1-chlorovinyl p-tolyl sulfoxides Z-178 and -178 were synthesized from 4-phenyl-2-butanone and they were treated with t-PrMgCl followed by iV-lithio indole. As shown in equation 42, this reaction gave a mixture of isomers ( -179 and Z-179) in relatively good yields but with low stereoselectivity. 

Problem 17.43 Show how acetone can be converted into 4-phenyl-2-butanone using enamine alkylation. M... 

Figure 22.4 Electroenzymatic reduction of 4-phenyl-2-butanone catalyzed by HLADH with in situ indirect electrochemical regeneration of NADH.

A. 1-Diazo-4-phenyl-2-butanone. A 1-L Erlenmeyer flask equipped with a two-inch magnetic stirring bar and a two-hole rubber stopper fitted with a 125-mL Teflon stopcock separatory funnel (Note 2 and a drying tube filled with potassium hydroxide (Note 3) is charged with a solution of 200 mmol (3.4 equiv) of diazomethane (Note 4) in 600 mL of dry ether. The solution is cooled to 0°C and stirred at high speed (Note 5). To this cooled solution, 10.0 g (59 mmol) of hydrocinnamoyl chloride (3-phenylpropionyl chloride) (Note 6) diluted to 125 mL with anhydrous ether is added dropwise over a 1 -hr period. The resulting reaction mixture is stirred cold for an additional 0.5 hr and then at room temperature for 1 hr. After this period of time the... 

Diazomethane is prepared as described in Org. Synth., Coll. Vol. /V1963, 250, with 50 g of Diazald (from Aldrich Chemical Company, Inc.) in 300 mL of ether added to 15 g of KOH in 25 mL of water, 30 mL of ether, and 50 mL of 2-(2-ethoxy-ethoxy)ethanol. One equivalent of diazomethane becomes incorporated in the reaction product, and the remainder serves as a scavenger for the HCI produced as a reaction by-product. The excess of diazomethane called for in this procedure is necessary to inhibit the undesired formation of 1-chloro-4-phenyl-2-butanone. The submitters report that this reaction can be performed on twice this scale with comparable results. 

The high rate of stirring reduces the production of 1-chloro-4-phenyl-2-butanone, a by-product of this reaction. 

A pure sample of diazo ketone can be obtained by chromatography on silica gel using 15% ethyl acetate/hexane as an eluent, Rf = 0.37. The checkers estimate the purity of the crude diazo ketone to be 90-91% based on careful column chromatography of 1 0-g aliquots. They further estimate that approximately 5-6% of 1 -chloro-4-phenyl-2-butanone is also produced in the reaction. The spectral properties of 1-diazo-4-phenyl-2-butanone are as follows 1H NMR (300 MHz, CDCI3) 8 2.59-2.64 (m, 2 H), 2.95 (t, 2 H, J = 7) 5.20 (broad s, 1 H), 7.17-7.31 (m, 5 H). 

The checkers found that on this scale a bulb-to-bulb (Kugelrohr) distillation could also be employed. The distilled product is contaminated with approximately 4-5% of 1 -chloro-4-phenyl-2-butanone which was produced in Step A. This impurity is easily removed by recrystallization from hexane. Alternatively, this impurity can be removed at the diazo ketone stage by column chromatography. The use of purified diazo ketone in Step B affords purer distilled product, but this modification has no significant effect on the overall yield. 

Diazo-4-phenyl-2-butanone 2-Butanone, 1 -diazo-4-pihenyl- (8,9) (10290-42-3) Diazomethane Methane, diazo- (8,9) (334-88-3)... 

Enantioselective reduction of simple aliphatic ketones is one of the most challenging of the currently unresolved problems in this field. The Rh/4 complex catalyzed the hydrosilylation of 2-butanone with diphenylsilane at 0 °C, which after hydrolysis gave (S)-2-butanol in 56% ee (Scheme 3) [17]. 2-Octanone and 4-phenyl-2-butanone were reduced with diphenylsilane in the presence of the cationic Rh/EtTRAP-H at -50 °C and gave optical yields of 77% and 81%, respectively [12], The cationic Rh/(R,R)-t-Bu-MiniPHOS was also effective for the reduction of 4-phenyl-2-butanone with 1-naphthylphenylsilane at -20 °C, affording the R product in 80% ee [13]. 3-Methyl-2-butanone was reduced using the Rh/4 complex with 76% optical yield [17]. Hydrosilylation of cyclohexyl methyl ketone with the Rh/(R,S)-2 complex followed by hydrolysis afforded the R alcohol in 87% ee [8]. Highly enantioselective hydrosilylation of pinacolone with diphenylsilane at -20 °C was achieved by means of the Rh/4 complex and yielded the desired R product in 95% ee [17]. 

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