A-Methoxyacetophenone

The first term was found to correspond to the rate of enolisation (measured by an NMR study of hydrogen-deuterium exchange at the methylene group). The second term predominates at [Cu(II)] > 10 M and is characterised by a primary kinetic isotope effect of 7.4 (25 °C) and a p value of 1.24. Addition of 2,2 -bipridyl (bipy) caused an increase in 2 up to a bipy Cu(II) ratio of 1 1 but at ratios greater than this 2 fell gradually until the enolisation term dominated. The oxidation of a-methoxyacetophenone is much slower but gives a similar rate... 

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. 

Ethyl 3-phenylpropynoate and a>-methoxyacetophenone condense in the presence of ethoxide ion to give 5-methoxy-4,6-diphenylpyran-2-one and clearly much variation in substituents is possible in this synthesis. 

Camuzat-Dedenis, B. Provot, O. Moskowitz, H. Mayrargue, J. Reaction of phosphonium ylides and aromatic nitriles under Lewis acid conditions and easy access to aryl-substituted a-methoxyacetophenones. Synthesis 1999, 1558-1560. 

Many reactions of ketones were performed with methanolic DIB in either an acidic or alkaline environment. When DIB is dissolved in methanol (or other alcohols) an exchange with acetate takes place, so that the reacting species may be PhI(OMe)OAc or PhI(OMe)2 the latter is actually an isolable compound [12]. Oxidation of methanol at room temperature is negligible. Acetophenones react with DIB in methanol-sulphuric acid affording mixtures of a-methoxyacetophenones (minor products) and rearranged esters. A solvent change from methanol to... 

Subramanian [18] has used gas chromatography-mass spectrometry to study the photodecomposition products such as benzaldehyde, a-hydroxyacetophenone, phenyl glycol, a-methoxyacetophenone, and a-henzyloxyacetophenone produced upon UV irradiation of polystyrene peroxide. Diaz and co-workers [19] carried out similar studies on polybenzyl methacrylates and polybenzyl acrylates. 

Obtained by Claisen rearrangement of 2-hydroxy-4-allyloxy-a-methoxyacetophenone by heating for 2 h at 190-195° under reduced pressure (67%) [4957]. 

Obtained by reaction of potassium persulfate with 2,4-di-ethoxy-6-hydroxy-a-methoxyacetophenone in the presence of aqueous sodium hydroxide (Elbs reaction), (33%) [4867], (25%) [4854]. 

Obtained by reaction of dimethyl sulfate with 2,4-diethoxy-3,6-dihydroxy-a-methoxyacetophenone in the presence of potassium carbonate in refluxing acetone for 2.5 h [4993], (27%) [4867] or for 12 h [4854]. 

Figure 6.6 MS of (a) a-methoxyacetophenone and (b) a-benzyloxy acetophenones. Reproduced with permission from K. Subramanian, European Polymer Journal, 2002, 38,1167. 2002, Elsevier [43]...

---