4 -methoxyacetophenone reduction

In a number of other cases it has been reported or implied that a single diastereomeric pinacol was formed, but the stereochemistry of the product was not determined these reports come from studies upon the electrochemical reduction of 3-acetylpyridine 87), p-acetamidobenzaldehyde 9I>, (3-di-methylaminopropiophenone 91 p-aminoacetophenone (which affords one pinacol in acid and the other in alkali)92), and the reduction of a mixture of p-dimethylaminoacetophenone and p-methoxyacetophenone to afford a mixed pinacol (87) 93>. 

Bandini and co-workers studied the zinc triflate-bis(oxazohne)-catalyzed reduction of a-alkoxy-ketones with catecholborane. The example in Figure 9.76 shows the reduction of a-methoxyacetophenone 252. l-Phenyl-2-methoxyethanol 254 was isolated in 78% yield and 82% ee. 

There is a dramatic reduction of water consumption and of aqueous effluents 35 kg per ton of 4-methoxyacetophenone instead of 4500 kg per ton with the old process. 

The ewrfo-configuration of the hydroxyketones 82 and 83 formed from camphorquinone has been unequivocally established 15> and shown to be related to configurations of the aldehyde adducts. This stereochemical result requires attack from the normally more hindered side of the molecule. As discussed earlier (cf. Table 4) m-methoxyacetophenone sensitized the reduction of camphorquinone in 2-propanol, and benzo-... 

Sec. alcohols, can be oxidized to ketones with Raney-Ni and a H -acceptor carbonyl groups and carbon double and triple bonds can be reduced with Raney-Ni and a H2-donor. The hydrogen adsorbed by the Ni may be sufficient for the reduction, so that the addition of a H2-donor is not necessary.—E Dihydrocholesterol refluxed with cyclohexanone as H2-acceptor in toluene in the presence of Raney-Ni with vigorous stirring for 24 hrs. —cholestanone. Y 80%.—Anisyli-dene-p-methoxyacetophenone and diethylcarbinol as H2-donor refluxed in toluene in the presence of Raney-Ni for 24 hrs. - >- l,3-bis-(p-methoxyphenyl)propane. Y 80%. (F. e. s. E. C. Kleiderer and E. C. Kornfeld, J. Org. Chem. 13, 455 (1948).)... 

The loss of a methoxyl group from the ring of an aromatic ether occurred in the regioselective photocyclisation of 2-methoxystilbene to phenanthrene in a mixture of sulphuric acid and tert-butanol with elimination of methanol (ref. 146). Phenanthrenes are also obtained by treatment of 2,2 -dialkoxystilbenes with low valent titanium. The same pathway is involved as in the reduction of 2-methoxyacetophenone to 9,10-dimethylphenanthrene referred to earlier (ref.99). 

Reductive alkylation of o-methoxyacetophenone is the first step of a controlled synthesis of 2-alkylcyclohexenones reported by Mander (Scheme... 

In another area, the asymmetric reductive acylation of ketoxime of m-methoxyacetophenone was developed by Kim and co-workers, in 2010. This process was catalysed by a combination of lipase CALB with a palladium nanocatalyst in the presence of ethyl methoig acetate as an acyl donor, molecular sieves in toluene at 70 °C under 0.1 bar of hydrogen pressure. It allowed the formation of the corresponding almost enantiopure amide in high yields of up to 91% and with enantioselectivity of 98% ee, as shown in Scheme 8.77. The utility of this novel methodology was applied to the total synthesis of the calcimimetic (-l-)-NPS R-568. 

Preparation by reduction of 3-formyl-2,4-dihydroxy-6-methoxyacetophenone with hydrochloric acid and amalgamated zinc in gently heated aqueous methanol (64%) [3036]. 

Figure 9.S Biocatalytic anti-Prelog stereoselective reduction of 4 -methoxyacetophenone with immobilized Trigonopsis variabilis AS2.1611 cells in IL-containing cosolvent systems.

The presence of certain ILs might lead to a mild permeabUization of the cell membrane and thereby facilitate substrate access to the cytosol. The addition of 2.5% (v/v) [C20HMIM][N03] in aqueous buffer substantially boosted the reaction efficiency of the anti-Prelog stereoselective reduction of 4 -methoxyacetophenone to (J )-l-(4 -methoxyphenyl)ethanol with immobilized Tr onopsis variabUis cells (Figure 9.5). Also, the presence of [CzOHMIMjINOs] allowed the cells to tolerate with relatively high temperatures and substrate concentrations compared to those in aqueous buffer without IL [52]. 

In this case, the photoproduct was the p-methoxyacetophenone (13), a reduction product. The proposed mechanism (Scheme 2) was a simple homolysis of the carbon-oxygen bond. Ethanol serves as a hydrogen atom donor during this process, and in the presence of 1-M benzophenone or naphthalene the reaction was completely quenched, indicating a triplet reaction pathway. Benzophenone and naphthalene are known quenchers of acetophenones and have triplet energies of 68 and 62 kcal/mol, respectively. 

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